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Physics > Chapters 1-10 > Flashcards

Chapters 1-10 Flashcards

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1
Q

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Which of these is a NOT scientific hypothesis?

A. Protons carry an electric charge.

B. Undetectable particles are some of nature’s secrets.

C. Charged particles bend when in a magnetic field
D. All of the above are scientific hypotheses

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A

B. Undetectable particles are some of nature’s secrets

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2
Q

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Which of these often changes over time with further study?

A. Facts.
B. Theories
C. Both of the above.
D. Neither of the above.

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A

C. Both of the above

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3
Q

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A person who says, “that’s only a theory” likely doesn’t know that a scientific theory is a…

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A

Vast synthesis of well-tested hypotheses and facts.

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4
Q

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The use of inclined planes for Galileo’s experiments helped him to…

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A

discover the property called inertia.

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5
Q

The concept of inertia mostly involves…

A

mass.

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6
Q

When the string is pulled down slowly, the top string breaks, which best illustrates the…

A

weight of the ball.

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7
Q

When the string is pulled down quickly, the bottom string breaks, which best illustrates the…

A

mass of the ball.

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8
Q

The density of 1 kilogram of iron is ____ on the Moon.

A

the same.

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9
Q

A cart is pushed to the right with a force of 15 N while being pulled to the left with a force of 20 N. The net force on the cart is…

A

5 N to the left.

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10
Q

The equilibrium rule, ΣF=0 applies to…

A

vector quantities.

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11
Q

When you stand on two bathroom scales, with one foot on each scale and weight evenly distributed, each scale will read…

A

half your weight.

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12
Q

A bowling ball is in equilibrium when it…

A

is at rest & moves steadily in a straight-line path.

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13
Q

The force of friction can occur..

A

With sliding objects, in water, & in air.

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14
Q

When Nellie pushes a crate across a factory floor at a consant speed, the force of friction between the crate and the floor is…

A

Equal and opposite to Nellie’s push.

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15
Q

When Nellie pushes a crate across a factory floor at an increasing speed, the amount of friction between the crate and the floor is…

A

Less than Nellie’s push.

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16
Q

The average speed in driving 30 km in 1 hour is the same average speed as driving…

A

60 km in two hours.

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17
Q

An automobile cannot maintain a constant speed when…

A

accelerating & rounding a curve.

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18
Q

Acceleration and velocity are actually…

A

rates, but for different quantities.

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19
Q

The rate at which distance changes with time.

A

Velocity

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20
Q

If a falling object gains 10 m/s each second it falls, it’s acceleration is…

A

10 m/s per second.

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21
Q

A free-falling object has a speed of 30 m/s at one instant. Exactly one second later its speed will be…

A

more than 35 m/s

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22
Q

The distance fallen by a free-falling body…

A

increases each second when falling.

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23
Q

The intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment; a body of knowledge; an ongoing human activity; has beginnings that reced recorded history.

A

Science

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24
Q

relates to how much you know about something; about quantifying an observation.

A

Measurements.

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25
Q

In general, ______ refer to principles and procedures for the systematic pursuit of knowledge involving the recognitioin and formulation of a problem, the collection of data through observation and experiment, and the formulatioin and testing of hypotheses.

A

Scientific methods.

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26
Q

Must accept experimental findings; test for erroneous beliefs; understand objections and positions of antagonists.

A

Scientists

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27
Q

A close agreement by competent observers who make a series of observations about the same phenomenon.

A

Fact

As understanding of the world around us evolves and/or technology advances facts can evolve as well.

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28
Q

A scientific ___ is an educated guess that is only presumed to be facutal until supported by experiment.

A

Hypothesis

Caridnal rull in science “All hypotheses must be testable”. Must be susceptible, at the very least in princible, to being shown wrong.

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29
Q

If a hypothesis is not testable then it is more likely just a ….

A

speculation.

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30
Q

A hypothesi that has been tested repeatedly and has not been contradicted.

A

Law.

Laws often describe what nature does under certain conditions and can predict outcomes if those conditions are met.

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31
Q

A syntesis of a large body of information that encompasses well-tested and verified hypotheses about certain aspects of the natural world.

A

Theory

Theories often are about how nature works and can change as understanding changes.

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32
Q

The natural order and involves the discovery and recording of natural phenomena. It is about understanding the world around us.

A

Science

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33
Q

The interpretation and expression of human experience.

A

Art.

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34
Q

About nature’s purpose and often involves faith and worship of a supreme being. Leads to philosophical questions that can not be proven right or wrong.

A

Religion

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35
Q

The use of scientific knowlege for practical purposes and to provide tools for further exploration.

A

Technology.

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36
Q

_____ sciences include geology, astronomy, chemistry and physics.

_____ sciences include biology, zoology and botany.

A

Physical; Life

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37
Q

The study of nature and properties of matter and energy. Topics include mechanics, heat, light and other radiation, sound, electricity and magnetism and the structure of atoms.

A

Physics.

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38
Q

Every object in the universe has a proper place determined by a combination of four elements: earth, water, air and fire. Any object not in it’s proper place will strive to get there.

A

Natural motion.

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39
Q

Produced by external pushes or pulls on objects.

A

Violent motion.

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40
Q

Gallileo demolished Aristotles assertions in the early 1500s. Galileo’s discovery: Objects of different weight fall to the ground at the same time in the absence of air resistance. A moving object needs no force to keep it moving in the absence of friction.

A

Galileo’s Concept of Inertia.

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41
Q

A push or pull; Many different sources such as gravitational, electrical, frictional or you pushing a box.

A

Force.

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42
Q

Property of matter to resist changes in motion; depends on the amount of matter in an object.

A

Inertia

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43
Q

Galileo’s Concept of Inertia: Balls rollon on ____ sloping planes picked up speed.

A

Downward.

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44
Q

Galileo’s Concept of Inertia: Balls rolling on ____ sloping planes lost speed.

A

Upward.

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45
Q

Galileo’s Concept of Inertia: A ball on a ____ plane must maintain speed forever.

A

Horizontal

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46
Q

Galileo’s Concept of Inertia: If a ball comes to rest it is not due to its “nature,” but due to…

A

friction.

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47
Q

The use of inclined planes for Galileo’s experiments helped him to…

A

discover the property called inertia.

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48
Q

A quantity whose description requires both magnitude (how much) and direction (which way); can be represented by arrows drawn to scale, called vectors.

A

Vector quantity.

Length of arrow represents magnitude and arrowhead shows direction.

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49
Q

Combination of all forces that change an objects state of motion.

A

Net force.

If you pull on a box with 10 N and a friend pulls oppositely 5 N, the net force is 5 N in the direction you are pulling.

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50
Q

The concept of inertia mostly involves…

A

mass.

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51
Q

The density of 1 kilogram of iron is…

A. less on the Moon

B. the same on the Moon.

C. greater on the moon.

A

B. the same on the Moon

Both mass and volume of 1 kilogram of iron is the same everywhere, so density is the same everywhere.

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52
Q

A cart is pushed to the right with a force of 15 N while being pulled to the left with a force of 20 N. The net force on the cart is…

A

5 N to the left.

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53
Q

The vector sum of forces acting on a nonaccelerating object equals zero.

A

Equilibrium Rule

In equation form: ΣF = 0

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54
Q

When you stand on two bathroom scales, with one foot on each scale and weight evenly distributed, each scale will read…

A

half your weight.

You are at rest on the scales, so ΣF=0. The sum of the two upward support forces is equal to your weight.

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55
Q

A bowling ball is in equilibrium when it…

A. is at rest

B. moves steadily in a straight-line path.

C. both of the above

D. none of the above.

A

C. both of the above.

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56
Q

Newton’s First Law states that an object ____.

A. at rest will remain at rest unless acted on by an outside force.

B. will continue moving at the same velocity unless acted on by an outside force.

C. will continue moving in a straight line unless acted on by an outside force.

D. that is not moving will never move unless a force acts on it.

E. All of the above.

A

E. all of the above.

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57
Q

The law of inertia applies to…

A

both moving and nonmoving objects.

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58
Q

After a cannon ball is fired into frictionless space, the amount of forced needed to keep it going equals…

A

zero, since no force is necessary to keep it moving.

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59
Q

A sheet of paper can be withdrawn from under a container of milk without toppling it, if the paper is jerked away quickly. The reason this can be done is that…

A

the milk carton has inertia.

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60
Q

One object has twice as much mass as another object. The first object also has twice as much ____.

A

inertia.

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61
Q

Compared to its weight on earth, a 50 kg object on the moon will weigh…

A

less.

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62
Q

A 10 N force west and a 30 N force east act on an object concurrently. What is the net force acting object?

A

20 N east.

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63
Q

Equlibrium occurs when ____.

A. All of the forces acting on an object are balanced.

B. The sum of the forces acting rightward equal to the sum of the forces acting leftward.

C. The sum of the forces acting upward equal to the sum of the forces acting downward.

D. The net force is zero.

E. All of the above.

A

E. All of the above.

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64
Q

The force of friction can occur..

A. with sliding objects

B. in water

C. in air

D. all of the above.

A

D. all of the above.

Friction can also occur for objects at rest. If you push horizontally on your book and it doesn’t move, then friction between the book and the table is equal and opposite to your push.

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65
Q

Motion of objects is always described as _____ to something else.

A

relative.

  • Examples:*
  • You walk on the road relative to earth, but earth is moving relative to the Sun. So your motion relative to the Sun is different from your motion relative to Earth.*
  • Driving on the interstate at 70 mph and you look over at the traffic going the opposite direction. What do you notice.*
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66
Q

Defined as the distance covered per amount of travel time.

A

speed.

  • Units are meters per second. *
  • In equation form: speed= distance/time*
  • Example: A girl runs 4 metes in 2 seconds. Her speed is 2 m/s.*
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67
Q

The speed of an object at any given instance in time.

A

Instantaneous Speed.

Example: When driving from home to the local movie theatre, is the trip a constant speed or does it change when you stop at a red light. Your instantaneous speed is reading your speedometer at any time.

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68
Q

The entire distance covered divided by the total travel time.

Doesn’t indicate various instantaneous speeds along the way. You lose this information by taking the average.

A

Average speed.

  • In equation form: Average speed = total distancecovered/time interval.*
  • Example: Drive a distance of 200km in 2 h and your average speed is 100 km/h.*
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69
Q

The average speed in driving 30 km in 1 hour is the same average speed as driving…

A

60 km in two hours.

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70
Q

Vector vs. Scalar Quantities

_____ have both Magnitude and Direction.

Examples: Velocity, Force, acceleration.

_____ have only Magnitude.

Examples: Speed, mass, distance, time.

A

Vectors’; Scalars’

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71
Q

A description of the instantaneous speed of the object & what direction the object is moving.

A

Velocity.

Velocity is a vector quantity. It has magnitude: instantaneous speed, & direction: direction of an object’s motion.

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72
Q

_____ is a steady speed, neither speeding up or slowing down.

_____ is constant speed and constant direction. (straight-line path with no acceleration).

A

Constant speed; constant velocity.

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73
Q

Rate at which velocity changes over time. Involves a change in speed or a change in direction, or both.

A

Acceleration.

  • In equation form: Acceleration = change in velocity/time interval*
  • Unit of acceleration is unit of velocity/unit of time.*
  • Example:*
  • Your car’s speed right now is 40 km/h. Your car’s speed 5 seconds later is 45km/h. Your car’s change in speed is 45-40=5km/h. Your car’s acceleration is 5 km/h/5s = 1km/h/s.*
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74
Q

An automobile cannot maintain a constant speed when..

A. accelerating

B. rounding a curve.

C. both of the above.

D. none of the above.

A

C. both of the above.

When rounding a curve, the automobile is accelerating, for it is changing direction.

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75
Q

Acceleration and velocity are actually…

A

rates, but for different quantities.

Velocity is the rate at which distance changes with time; acceleration is the rate at which velocity changes with time.

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76
Q

If a falling object gains 10 m/s each second it falls, its acceleration is…

A

10 m/s per second

It is common to express 10m/s per second as 10m/s/s or 10 m/s2

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77
Q

Falling under the influence of gravity only- with no air resistance.

A

Free fall.

  • Freely falling objects on Earth accelerate at the rate of 10 m/s2(more precisely, 9.8 m/s2).*
  • So under free fall, when acceleration is 10 m/s2, the speed is 10 m/s after 1 s. *
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78
Q

A free-falling object has a speed of 30 m/s at one instant. Exactly one second later its speed will be…

A

more than 35 m/s.

  • One second later its speed will be 40 m/s, which is more than 35 m/s.*
  • The distance covered by an accelerating object starting from rest is distance= (1/2) x acceleration x time x time.*
  • So, under free fall, when acceleration is 10 m/s2, the distance is 5 m after 1 s, 20 m after 2 s, 45 m after 3 s, and so on.*
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79
Q

_______ depends on the kinds of material and how much they are pressed to gether.

A

The Force of Friction

  • The Force of Friction is due to tiny surface bumps and to “stickiness of the atoms on a material’s surface.*
  • Friction ALWAYS is in the direction of opposing motion.*
  • Example: Friction between a crate on a smooth wooden floor is less than that on a rough floor.*
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80
Q

When Sanjay pushes a refrigerator across the kitchen floor at a constant speed, the force of friction between the refrigerator and the floor is…

A

Equal and opposite to Sanjay’s push.

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81
Q

When Sanjay pushes a refrigerator across a kitchen floor at an increasing speed, the amount of friction between the refrigerator and the floor is…

A

less than Sanjay’s push.

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82
Q

Consider a cart pushed along a track with a certain force. If the force remains the same while the mass of the cart decreases to half, the acceleration of the cart…

A

Doubles.

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83
Q

Push a cart along a track so twice as much net force acts on it. If the acceleration remains the same, what is a reasonable explanation?

A

The mass of the cart doubled when the force is doubled.

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84
Q

A 5-kg iron ball and a 10-kg iron ball are dropped from rest. For negligible air resistance, the acceleration of the heavier ball will be…

A

the same.

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85
Q

A 5-kg iron ball and a 10-kg iron ball are dropped from rest. When the free-falling 5-kg ball reaches a speed of 10m/s, the speed of the free-falling 10-kg ball is…

A

10 m/s.

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86
Q

Occurs when acceleration terminates (when air resistance equals weight and net force is zero).

A

Terminal speed.

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87
Q

Same as terminal speed, with direction implied or specified.

A

Terminal velocity.

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88
Q

If a 50-N person is to fall at terminal speed, the air resistance needed is…

A

50 N

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89
Q

As the skydiver falls faster and faster through the air, air resistance…

A

increases.

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90
Q

As the skydiver continues to fall faster and faster through the air, net force…

A

decreases.

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91
Q

As the skydiver continues to fall faster and faster through the hair, her acceleration…

A

decreases.

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92
Q

Consider a heavy and light person jumping together with same-size parachute fro the same altitude. Who will reach the ground first?

A

The heavy person.

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93
Q

Between one thing and another; requires a pair of forces acting on two objects.

A

Interaction.

Example: interaction of hand and wall pushing on each other. Force pair– you push on wall; wall pushes on you.

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94
Q

A soccer player kicks a ball with 1500 N of force. The ball exerts a reaction force against the player’s foot of…

A

1500 N

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95
Q

When you step off a curb, Earth pulls you downward. The reaction to this force is…

A

You pulling Earth upward.

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96
Q

Consider a high speed bus colliding head-on with an innocent bug. The force of impact splatters the unfortunate bug over the windsheild. Which is greater, the force on the bug or the force on the bus?

A

Both are the same.

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97
Q

Two people of equal mass on slippery ice push off from each other. Will both move at the same speed in opposite directions?

A

Yes.

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98
Q

When lift equals the weight of a helicopter, the helicopter…

A

hovers midair.

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99
Q

When lift is greater, the helicopter…

A

climbs up.

100
Q

Slightly tilted wings of airplanes deflect…

A

oncoming air downward to produce lift.

101
Q

Compared with a lightweight glider, a heavier glider would have topush air…

A

downward with greater force.

102
Q

Referring to the figure, which of the following are true statements?

A. 100 km/h is the resultant of the 80- and the 60-km/h vectors.

B. The 80-km/h vector can be considered a component of the 100-km/h vector.

C. The 60-km/h vector can be considered a component of the 100-km/h vector.

D. All of the above are correct.

A

D. All of the above are correct.

103
Q

A moving object has…

A. momentum

B. energy

C. speed

D. All of the above.

A

D. all of the above.

104
Q

When the speed of an object is doubled, the momentum…

A

doubles.

105
Q

A cannonball shot from a cannon with a long barrel will emerge with greater speed because the cannonball recieves a greater…

A

impulse.

106
Q

A fast-moving car hitting a haystack or a cement wall (and stopping for both) produces vastly different results.

  1. Do both experience the same change in momentum?
  2. Do both experience the same impulse?
  3. Do both experience the same force?
A

Yes for 1 and 2.

107
Q

When a dish falls, will the change in momentum be less if it lands on a carpet than if it lands on a hard floor?

A

No, both are the same.

108
Q

Occurs when colliding objects rebound without lasting deformation or any generation of heat.

A

Elastic collision.

109
Q

Occurs when colliding objects result in deformation and/or the generation of heat.

A

Inelastic collision.

110
Q

Freight car A is moving toward identical freight car B that is at rest. When they collide, both freight cars couple together. Compared with the initial speed of freight car A, the speed of the coupled freight cars is…

A

Half

111
Q

Mover of substances; both a thing and a process; observed when it is being transferred or being transformed; a conserved quantity

A

Energy

112
Q

Substance we can see, smell and feel; occupies space.

A

Matter.

113
Q

Involves force and distance (force x distance)

A

Work

114
Q

Two things occur whenever work is done:

A

Application of force & movement of something by that force.

115
Q

If you push against a stationary brick wall for several minutes, you do no work…

A

on the wall.

116
Q

Work is done in lifting a barbell. How much work is done in lifting a barbell that is twice as heavy the same distance?

A

Twice as much.

117
Q

You do work when pushing a cart with a constant force. If you push the cart twice as far, then the work you do is…

A

Twice as much.

118
Q

Measure of how fast work is done.

A

Power.

In equation form: power= work done/time interval

119
Q

A job can be done slowly or quickly. Both may require the same amount of work, but different amounts of…

A

Power

120
Q

______ energy is due to position or to motion, or both.

A

Mechanical.

There are two forms of mechanical energy: potential energy & kinetic energy.

121
Q

Stored energy held in readiness with a potential for doing work.

A

Potential Energy.

122
Q

Does a car hoisted for repairs in a service station have increased potential energy relative to the floor?

A

Yes.

123
Q

Energy of motion; depends on the mass of the object and square of its speed.

A

Kinetic energy.

124
Q

Must a car with momentum have kinetic energy?

A

Yes, due to motion alone.

125
Q

Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes.

A

Law of conservation of energy.

126
Q

Consider the system of a bow and arrow. In drawing the bow, we do work on the system and give it potential energy. When the bowstring is released, most of the potential energy is transferred to the arrow as kinetic energy and some as heat to the bow. Suppose the potential energy of a drawn bow is 50 joules and the kinetic enegy of the shot arrow is 40 joules. Then…

A

10 joules go to warming the bow.

127
Q

Device for multiplying forces or changing direction of forces; cannot create energy but can transform energy from one form to another, or transfer energy from one location to another; cannot multiply work or energy.

A

Machine

128
Q

Rotates on a point of support called the fulcrum; allows small force over a large distance and large force over a short distance.

A

Lever

129
Q

operates like a lever with equal arms– changes the direction of the imput force.

A

pulley.

130
Q

In an ideal pulley system; a woman lifts a 100-N crate by pulling a rope downward with a force of 25 N. For every 1-meter length of rope she pulls downward, the crate rises…

A

25 centimeters.

131
Q

When an object turns about an internal axis, it is undergoing _____ or rotation.

A

Circular motion.

  • Circular motion is characterized by two kinds of speeds: *
  • tangenital (or linear) speed*
  • rotational (or circular) speed*
132
Q

A ladybug sits halfway between the rotational axis and the outer edge of the turntable. When the turntable has a rotational speed of 20 RPM and the bug has a tangenitial speed of 2 cm/s, what will the rotational and tangential speeds of her friend who sits at the outer edge.

A

4 cm/s.

Distance is doubled, tangential speed is doubled.

133
Q

The property of an object to resist changes in its rotational state of motion is called…

A

rotational inertia

  • depends on the mass of the object & distribution of mass around axis of rotation*
  • The greater the distance between on object’s mass concentration and the axis, the greater the rotational inertia.*
134
Q

The tendency of a force to cause rotation is called _____.

A

torque.

  • Torque depends on three factors:*
  • Magnitude of the force*
  • The direction in which it acts*
  • The point at which it is applied on the object*

The equation for torque is torque= lever arm x force

135
Q

____ is the average position of all the mass that makes up the object.

A

Center of mass

136
Q

_____ is the average position of weight distriburion.

A

Center of gravity.

Since weight and mass are proportional, center of gravity and center of mass usually refer to the same point of an object.

137
Q

Any force directed toward a fixed center is called a ______.

A

centripetal force.

Example: To whirl a tin can at the end of a string, you pull the string tward the center and exert a centripetal force to keep the can moving in a circle.

138
Q

Although a centripetal force is center directed, an occupant inside a rotating system seems to experience an outward force. This apparent outward force is called ______.

A

Centrifugal force.

Centrifugal means “center-fleeing” or “away fromt the center.”

139
Q

The “inertia of rotation” of rotating objects is called _______.

A

Angular momentum.

140
Q

Suppose by pulling the weights inward, the rotational inertia of the man reduces to half its value. By what factor would his angular velocity change?

A

Double

141
Q

If no external net torque acts on a rotating system, the angular momentum of that system remains constant.

A

The law of conservation of angular momentum.

142
Q

Newton was not the first to discover gravity. Newton disoverd that gravity is…

A

universal.

143
Q

When an elevator accelerates upward, your weight reading on a scale is…

A

greater.

144
Q

When an elevator accelerates downward, your weight reading is…

A

less.

145
Q

When the elevator cable breaks, the elevator falls freely, so your weight reading is…

A

zero.

146
Q

If you weigh yourself in an elevator, you’ll weigh more when the elevator…

A

accelerates upward.

147
Q

_____ is an alteration of space around Earth (or any object with mass.)

A

Gravitational field

148
Q

When the star becomes so small and the gravitational force at the surface becomes so large that even light cannot escape the surface, anything in its vicinity will be attracted by warped space-time and lost forever.

A

Black hole.

149
Q

Any object that moves through the air or space under the influence of gravity, continuing in motion by its own inertia.

A

projectile.

150
Q

Projectile motion is a combination of…

A

A horizontal component, and a verticle component.

151
Q

Curved path of a projectile that undergoes acceleration only in the vertical direction, while moving horizontally at a constant speed.

A

parabola

152
Q

When no air resistance acts on a fast-moving baseball, it’s acceleration is….

A

downward, g.

153
Q

A scientific hypothesis deemed valid must have a test for proving it _____.

A

wrong.

154
Q

Technology is a tool for…

A

Applying scientific discoveries.

155
Q

Different materials, A(2kg of sand), B(12kg of iron), C(15kg of water), and D(5kg of pillow), rest on a table .From greatest to least, rank them by how much they resist being set in motion.

A

C, B, D, A

156
Q

Different materials, A(2kg of sand), B(12kg of iron), C(15kg of water), and D(5kg of pillow), rest on a table. From greatest to least, rank them by the support (normal) force the table exerts on them.

A

C, B, D, A.

157
Q

Which of the following involves passion, talent, and intelligence?

A. art
B. literature
C. science
D. music
E. all of these

A

E. all of these

158
Q

A truly educated person is knowledgeable about

A. science.
B. the arts.
C. religion.
D. all of these

A

D. all of these

159
Q

Science, art, and religion do not contradict one another because

A. if you choose science, you can forget about religion and art.
B. if you choose the right one, you can forget the other two.
C. all three have different domains.
D. if you choose religion and art, you can forget about science.

A

C. all three have different domains.

160
Q

The statement, “There are regions beneath the Earth’s crust that will always be beyond the reach of scientific investigation,” is a

A. hypothesis.
B. theory.
C. speculation.
D. fact.
E. scientific statement.

A

C. speculation

161
Q

A scientific hypothesis may turn out to be right or it may turn out to be wrong. If it is a valid hypothesis, there must be a test for proving it

A. wrong.
B. right.

A

A. wrong

162
Q

In science, an educated guess is a

A. theory.
B. hypothesis.
C. both of these

A

B. hypothesis

163
Q

Science is a body of knowledge that

A. condenses knowledge into testable laws.
B. is an ongoing activity of humans.
C. describes order in nature.
D. All of the above choices are correct.
E. None of the above choices are correct.

A

D. All of the above choices are correct.

164
Q

From greatest to least, rank them by how much they resist being set into motion.

A

C, A, D, B.

165
Q

A different scaffold that weighs 400 N supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N.

What is the reading in the right-hand scale?
Express your answer to two significant figures and include the appropriate units.

A

T= 500 N

166
Q

The sketch shows a painter’s scaffold in mechanical equilibrium. The person in the middle weighs 500 N, and the tensions in each rope are 400 N.

What is the weight of the scaffold?
Express your answer to two significant figures and include the appropriate units.

A

W= 300 N

167
Q

Henry Heavyweight weighs 1400N and stands on a pair of bathroom scales so that one scale reads twice as much as the other.

What are the scale readings?

A

W1=933; W2=467

168
Q

When a rocket ship accelerating in outer space runs out of fuel, it

A. accelerates for a short time, slows down, and eventually stops.

B. no longer accelerates.
C. accelerates for a short time, then slows down to a constant velocity.

A

B. no longer accelerates

169
Q

If no external forces are acting on a moving object, it will

A. continue moving at the same speed.
B. continue moving at the same velocity.
C. move slower and slower until it finally stops.

A

B. continue moving at the same velocity.

170
Q

According to Newton’s law of inertia, a railroad train in motion should continue going forever even if its engine is turned off. We never observe this because railroad trains

A. are much too heavy.
B. always have forces that oppose their motion.
C. must go up and down hills.
D. move too slowly.

A

B. always have forces that oppose their motion.

171
Q

A package falls off a truck that is moving at 30 m/s. Neglecting air resistance, the horizontal speed of the package just before it hits the ground is

A. less than 30 m/s but larger than zero.
B. zero.
C. more than 30 m/s.
D. about 30 m/s.
E. More information is needed for an estimate.

A

D. about 30 m/s.

172
Q

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that

A. the milk carton has inertia.
B. gravity tends to hold the milk carton secure.
C. there is an action-reaction pair of forces.
D. the milk carton has no acceleration.
E. none of these

A

A. the milk carton has inertia.

173
Q

Hang from a pair of gym rings and the upward support forces of the rings will always

A. add up to equal your weight.
B. each be half your weight.
C. each equal your weight.

A

A. add up to equal your weight.

174
Q

Three balls of different masses are thrown straight upward with initial speeds as indicated.

From fastest to slowest, rank the speeds of the balls 1 s after being thrown.

A

C, A, B

175
Q

Jogging Jake runs along a train flatcar that moves at the velocities shown in positions A-D.

From greatest to least, rank the velocity of Jake relative to a stationary observer on the ground. Call the direction to the right positive.

A

C, D, A, B.

176
Q

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds?

A. about 60 m/s
B. about 110 m/s
C. about 100 m/s
D. about 80 m/s
E. about 50 m/s

A

E. About 50 m/s

177
Q

Someone standing at the edge of a cliff throws one ball straight up and another ball straight down at the same initial speed. Neglecting air resistance, the ball to hit the ground below the cliff with the greater speed will be

A. the one thrown downward.
B. the one thrown upward.
C. neither – they will both hit with the same speed.

A

C. neither– they will both hit the same speed.

178
Q

A bullet is dropped into a river from a very high bridge. At the same time, another bullet is fired from a gun, straight down towards the water. Neglecting air resistance, the acceleration just before striking the water

A. depends on how high they started.
B. is the same for each bullet.
C. is greater for the dropped bullet.
D. is greater for the fired bullet.
E. none of these

A

B. is the same for each bullet.

179
Q

A bullet is fired straight down from the top of a high cliff. Neglecting air resistance, the acceleration of the bullet in meters per second per second

A. depends on the height of the cliff.
B. is 9.8.
C. is less than 9.8.
D. is more than 9.8.

A

B. is 9.8

180
Q

The two measurements necessary for calculating average speed are

A. velocity and distance.
B. distance and acceleration.
C. acceleration and time.
D. velocity and time.
E. distance and time.

A

E. distance and time

181
Q

A horse gallops a distance of 10 kilometers in a time of 30 minutes. Its average speed is

A. 30 km/h.
B. 15 km/h.
C. 40 km/h.
D. 20 km/h.

A

D. 20 km/h

182
Q

A car maintains a constant velocity of 100 km/hr for 10 seconds. During this interval its acceleration is

A. 110 km/hr.
B. zero.
C. 10 km/hr.
D. 1000 km/hr.

A

B. zero

183
Q

While an object near the Earth’s surface is in free fall, its

A. acceleration increases.
B. mass increases.
C. velocity increases.
D. mass decreases.

A

C. velocity increases.

184
Q

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is

A. equal to the product of its mass times its weight.
B. equal to its weight.
C. zero.
D. equal to its weight divided by its mass.

A

C. zero

185
Q

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be

A. 10 m/s.
B. 30 m/s.
C. 20 m/s.
D. 40 m/s.

A

C. 20 m/s

186
Q

If an object falling freely were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be

A. greater than the second before.
B. doubled.
C. constant.
D. less and less each second.

A

A. greater than the second before

187
Q

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is

A. 6 km/h/s.
B. 600 km/h/s.
C. 60 km/h/s.
D. 10 km/h/s.
E. 3 km/h/s.

A

A. 6 km/h/s

188
Q

A ball is thrown upwards and returns to the same position. Compared with its original speed after release, its speed when it returns is about

A. half as much.
B. four times as much.
C. twice as much.
D. the same.

A

D. the same

189
Q

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration in meters per second per second is approximately

A. 8.
B. 24.
C. 0.
D. 5.

A

C. 0

190
Q

While a car travels around a circular track at a constant speed, its

A. acceleration is zero.
B. velocity is zero.
C. inertia is zero.
D. none of the above

A

D. none of the above

191
Q

If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity

A. the friction force increases.
B. the object accelerates in the direction of the applied force.
C. the object eventually slides to a stop.
D. none of the above

A

C. the object eventually slides to a stop

192
Q

An object cannot remain at rest unless which of the following holds?

A. The net force acting on it is zero.
B. The net force acting on it is constant and nonzero.
C. There are no forces at all acting on it.
D. There is only one force acting on it.

A

A. The net force acting on it is zero

If there is a net force acting on a body, regardless of whether it is a constant force, the body accelerates. If the body is at rest and the net force acting on it is zero, then it will remain at rest. The net force could be zero either because there are no forces acting on the body at all or because several forces are acting on the body but they all cancel out.

193
Q

If a block is moving to the left at a constant velocity, what can one conclude?

A. There is exactly one force applied to the block.
B. The net force applied to the block is directed to the left.
C. The net force applied to the block is zero.
D. There must be no forces at all applied to the block.

A

C. The net force applied to the block is zero.

If there is a net force acting on a body, regardless of whether the body is already moving, the body accelerates. If a body is moving with constant velocity, then it is not accelerating and the net force acting on it is zero. The net force could be zero either because there are no forces acting on the body at all or because several forces are acting on the body but they all cancel out.

194
Q

A block of mass 2kg is acted upon by two forces: 3N (directed to the left) and 4N (directed to the right). What can you say about the block’s motion?

A. It must be moving to the left.
B. It must be moving to the right.
C. It must be at rest.
D. It could be moving to the left, moving to the right, or be instantaneously at rest.

A

D. It could be moving to the left, moving to the right, or be instantaneously at rest.

The acceleration of an object tells you nothing about its velocity–the direction and speed at which it is moving. In this case, the net force on (and therefore the acceleration of) the block is to the right, but the block could be moving left, right, or in any other direction.

195
Q

A massive block is being pulled along a horizontal frictionless surface by a constant horizontal force. The block must be __________.

A. continuously changing direction
B. moving at constant velocity
D. moving with a constant nonzero acceleration
E. moving with continuously increasing acceleration

A

D. moving with a constant nonzero acceleration

Since there is a net force acting, the body does not move at a constant velocity, but it accelerates instead. However, the force acting on the body is constant. Hence, according to Newton’s 2nd law of motion, the acceleration of the body is also constant.

196
Q

Two forces, of magnitude 4N and 10N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________.

A. cannot have a magnitude equal to 5N
B. cannot have a magnitude equal to 10N
C. cannot have the same direction as the force with magnitude 10N
D. must have a magnitude greater than 10N

A

A. cannot have a magnitude equal to 5 N

197
Q

A force is a vector quantity because it has both

A. mass and acceleration.
B. action and reaction counterparts.
C. magnitude and direction.

A

C. magnitude and direction

198
Q

A 10-N falling object encounters 4 N of air resistance. The net force on the object is

A. 0 N.
B. 4 N.
C. 10 N.
D. 6 N.
E. none of these

A

D. 6 N

199
Q

block is dragged without acceleration in a straight-line path across a level surface by a force of 6 N. What is the force of friction between the block and the surface?

A. less than 6 N
B. 6 N
C. more than 6 N
D. need more information to say

A

B. 6N

200
Q

A car traveling at 22 m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration in meters per second per second of the car?

A. 220
B. 880
C. 800
D. 110
E. can’t be solved without the mass of the car

A

A. 220

201
Q

The human body can, under certain conditions, withstand an acceleration of 10 g. What net force would produce this acceleration of a 50-kg person?

A. about 500 N
B. about 25,000 N
C.about 5000 N
D. about 2500 N
E. none of these

A

C. about 5000 N

202
Q

A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first?

A. the heavy man
B. the light woman
C. Both should arrive at the same time.
D. not enough information

A

B. The light woman.

203
Q

A skydiver steps from a helicopter and falls for a few seconds until he reaches his terminal velocity. Thereafter, until he opens his parachute, his acceleration

A. is zero.
B. increases.
C. is constant.
D. decreases.
E. none of these

A

A. is zero

204
Q

For an action force, there must be a reaction force that

A. always acts in the same direction.
B. is slightly larger in amplitude than the action force.
C. is exactly equal in magnitude.
D. is slightly smaller in magnitude than the action force.

A

C. is exactly equal in magnitude

205
Q

A person is attracted toward the center of Earth by a 500-N gravitational force. The Earth is attracted toward the person with a force of

A. 1000 N.
B. zero.
C. 500 N.
D. 250 N.

A

C. 500 N.

206
Q

A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle that undergoes the greatest change in velocity will be the

A. Mack truck.
B. same for both.
C. Volkswagen.

A

C. Volkswagen

207
Q

It is correct to say that impulse is equal to

A. the force multiplied by the distance the force acts.
B. momentum.
C. velocity multiplied by time.
D. the change in momentum it produces.

A

D. the change in momentum it produces.

208
Q

A rifle recoils while firing a bullet. The speed of the rifle’s recoil is small because the

A. force against the rifle is smaller than against the bullet.
B. momentum of the rifle is smaller.
C. momentum is mainly concentrated in the bullet.
D. rifle has much more mass than the bullet.

A

D. rifle has much more mass than the bullet

209
Q

To catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball’s motion. Doing this reduces the force of impact on the player’s hand principally because the

A. relative velocity is less.
B. time of impact is decreased.
C. force of impact is reduced.
D. time of impact is increased.
E. none of these

A

D. time of impact is increased

210
Q

When you are in the way of a fast-moving object and can’t get out of its way, you will suffer a smaller force of impact if you decrease its momentum over a

A. short time.
B. long time.
C. same way either way

A

B. long time

211
Q

A car traveling along the highway needs a certain amount of force exerted on it to stop it in a certain distance. More stopping force is required when the car has

A. more momentum.
B. more mass.
C. less stopping distance.
D. all of these
E. none of these

A

D. all of these

212
Q

Recoil is noticeable if we throw a heavy ball while standing on roller skates. If instead we go through the motions of throwing the ball but hold onto it, our net recoil will be

A. small, but noticeable.
B. zero.
C. the same as before.

A

B. zero

213
Q

wo billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

A. 0
B. twice the sum of their original momentums
C. half the sum of their original momentums
D. impossible to determine without additional information

A

A. 0

214
Q

According to the impulse-momentum equation Ft = change in (mv), a person will suffer less injury falling on a wooden floor which “gives” than on a more rigid cement floor. The “F” in the above equation stands for the force exerted on the

A. only the person.
B. the sum of the force on the person and the force on the floor
C. only the floor.
D. either the force on the person or the force on the floor

A

E. either the force on the person or the force on the floor

215
Q

Which would produce more force: driving into a very massive concrete wall with no “give,” or having a head-on collision at the same speed with an identical car moving toward you with the same speed?

A. car
B. both the same
C. wall
D. impossible to predict without additional information

A

B. both the same

216
Q

If a monkey floating in outer space throws his hat away, the hat and the monkey will both

A. move a short distance and then go faster.
B. move away from each other at the same speed.
C. move a short distance and then slow down.
D. come to a stop after a few minutes.
E. move away from each other, but at different speeds.

A

E. move away from each other, but at different speeds.

217
Q

When a rifle is fired, it recoils as the bullet is set in motion. The rifle and bullet ideally acquire equal

A. amounts of kinetic energy.
B. but opposite amounts of momentum.
C. both of these
D. neither of these

A

B. but opposite amounts of momentum

218
Q

If the speed of a moving object doubles, which of the following also doubles?

A. kinetic energy
B. acceleration
C. momentum
D. all of the above

A

C. momentum

219
Q

Compared to the recoiling rifle, the bullet fired has

A. a greater kinetic energy.
B. a smaller speed.
C. a greater momentum.
D. all of the above

A

A. greater kinetic energy

220
Q

An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car’s speed

A. increases.
B. decreases.
C. doesn’t change.
D. cannot be determined with the information given

A

B. decreases

221
Q

If a ping pong ball and a golf ball are both moving in the same direction with the same amount of kinetic energy, the speed of the ping pong ball must be

A. less than the golf ball.
B. the same as the golf ball.
C. more than the golf ball.
D. impossible to predict without additional information

A

C. more than the golf ball

222
Q

A popular swinging-balls apparatus consists of an aligned row of identical elastic balls that are suspended by strings so they barely touch each other. When two balls are lifted from one end and released, they strike the row and two balls pop out from the other end. If instead one ball popped out with twice the speed of the two, this would be a violation of conservation of

A. energy.
B. momentum.
C. both of these
D. none of these

A

A. energy

223
Q

If you push an object twice as far while applying the same force, you do

A. half as much work.
B. the same amount of work.
C. four times as much work.
D. twice as much work

A

D. twice as much work

224
Q

If you do work on an object in one-third the usual time, your power output is

A. one third the usual power output.
B. three times the usual power output.
C. the usual power output.
D. impossible to predict without additional information.

A

B. three times the usual power output

225
Q

If an object is raised twice as high, its potential energy will be

A. four times as much.
B. twice as much.
C. half as much
D. impossible to determine unless the time is given.

A

B. twice as much

226
Q

When an automobile is braked to a stop, its kinetic energy is transformed to

A. energy of motion.
B. heat.
C. potential energy.
D. stopping energy.
E. energy of rest.

A

B. heat

227
Q

What task requires the most work; lifting a 50-kg sack 2 meters or lifting a 25-kg sack 4 meters?

A. the 25-kg sack
B. the 50-kg sack
C. Both require the same amount of work.
D. impossible to determine without knowing the contents of the sack

A

C. Both require the same amount of work

228
Q

Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed to do this job was

A. 1000 W.
B. 20,000 W.
C. 50 W.
D. 20 W.
E. 100 W.

A

C. 50 W

229
Q

A ball is projected into the air with 100 J of kinetic energy which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is

A. more than 100 J.
B. 100 J.
C. less than 100 J.
D. not enough information given

A

C. Less than 100 J

230
Q

Strictly speaking, more fuel is consumed by your car if an air conditioner, headlights, or even a radio is turned on. This statement is

A. true only if the car’s engine is running slowly.
B. totally false.
C. true only if the car’s engine is running fast.
D. true.

A

D. true

231
Q

Horses that move with the fastest linear speed on a merry-go-round are located

A. near the center.
B. anywhere, because they all move at the same speed.
C. near the outside.

A

C. Near the outside

232
Q

Suppose the circumference of a bicycle wheel is 2 meters. If it rotates at 1 revolution per second when you are riding the bicycle, then your speed will be

A. 1 m/s.
B. 6.28 m/s.
C. 3 m/s.
D. 2 m/s.
E. 3.14 m/s.

A

D. 2 m/s

233
Q

A broom is easier to balance on its end when the heavier end (the brush end) is

A. highest, farthest from your hand.
B. nearest your hand.
C. same either way

A

A. highest, farthest from your hand

234
Q

The rotational inertia of your leg is greater when your leg is

A. bent.
B. straight.
C. same either way

A

B. straight

235
Q

The center of mass of a human body is located at a point

A. that is fixed, but different for different people.
B. that is always directly behind the belly button.
C. that changes as a person bends over.
D. none of these

A

C. That changes as a person bends over

236
Q

The chef at the infamous Fattening Tower of Pizza tosses a spinning disk of uncooked pizza dough into the air. The disk’s diameter increases during the flight, while its rotational speed

A. remains constant.
B. decreases.
C. increases.

A

B. decreases

237
Q

A huge rotating cloud of particles in space gravitate together to form an increasingly dense ball. As it shrinks in size, the cloud

A. cannot rotate.
B. rotates slower.
C. rotates faster.
D. rotates at the same speed.

A

C. rotates faster

238
Q

Consider Earth and the Moon. As you should now realize, the gravitational force that Earth exerts on the Moon is equal and opposite to that which the Moon exerts on Earth. Therefore, according to Newton’s second law of motion __________.

A. the Moon has a larger acceleration than Earth, because it has a smaller mass
B. Earth has a larger acceleration than the Moon, because it has a larger mass
C. the Moon and Earth both have equal accelerations, because the forces are equal

A

A. The moon has a larger acceleration than Earth, because it has a smaller mass.

239
Q

A kilogram is a measure of an object’s ________.

A. weight
B. force
C. gravity
D. mass

A

D. mass

240
Q

Why would a bowling ball and a small marble fall down to the surface of the Moon at the same rate?

A. The force of gravity is proportional to the object’s mass.
B. The force of gravity on an object in a vacuum is zero.
C. The force of gravity is the same for each object.

A

A. the force of gravity is proportional to the object’s mass.

241
Q

If you stood on a planet having a mass four times that of Earth, and a radius two times that of Earth, how much would you weigh on that planet?

A

The same as your weight on Earth.

242
Q

Imagine that Earth had an identical twin planet, “Farth”, which is twice as far away from the Sun as Earth is. Compared to the force of gravity that Earth exerts on the Sun, how strong is the force of gravity that Farth exerts on the Sun?

A. one-fourth as strong
B. one-half as strong
C. the same strength
D. twice as strong

A

A. one-fourth as strong

243
Q

Suppose the Sun suddenly shrunk, reducing its radius by half (but its mass remaining the same). The force of gravity exerted on the Earth by the Sun would _________.

A. decrease by half
B. remain the same
C. double
D. quadruple

A

B. remain the same

244
Q

If one person is pushing to the right on a 300-kg cart with a force of 200 N, and another person is pushing to the left on the same cart with a force of 100 N, what is the acceleration of the cart?

A. 0.33 m/s/s
B. 1 m/s/s
C. 3 m/s/s
D. 100 m/s/s

A

A. 0.33 m/s/s

245
Q

Object A has three times as the mass of object B. Identical forces are exerted on the two objects. Which statement is true?

A. The speed of object A is three times that of object B after 3 seconds.

B. The speeds of the two objects are equal after 2 seconds.
C. The accelerations of the two objects are equal.
D. The acceleration of object B is three times that of object A.

A

D. The acceleration of object B is three times that of object A.

246
Q
A

Physics (3 decks)

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