Test 7

Question 1

What is the actual mechanical advantage of a machine that allows a man to life a 1000 N box with an input force of 250 N?

Answer 1

4

Question 2

Isaac Newton published the laws of motion and universal gravitation in his book?

Answer 2

Principia

Question 3

Physical quantities having both magnitude and direction are ? quantities.

Answer 3

vector

Question 4

Physical quantities having magnitude but not direction are ? quantities.

Answer 4

scalar

Question 5

In physics, any change in speed, direction, or both is?

Answer 5

acceleration

Question 6

Which of the following is not a form of assistance provided by simple machines?

Answer 6

increasing the work done

Question 7

The acceleration of gravity at the surface of the earth is?

Answer 7

9.81 m/s2

Question 8

What is the average speed of a car that travels 500 km in 10 hr?

Answer 8

50 km/hr

Question 9

The vector representing the change in an object’s position is?

Answer 9

displacement

Question 10

A 1 kg brick and a 100 kg safe were both dropped from the top of a tall building at the same time. If air resistance is ignored, which of the following statements is true?

Answer 10

Both hit the ground at the same time.

Question 11

The velocity at which the force of air resistance of a falling object equals the object’s weight is the ? velocity.

Answer 11

terminal

Question 12

A “center-seeking” force that causes an object to travel in a curved path rather than in a straight line is ? force.

Answer 12

centripetal

Question 13

The SI unit of power is the?

Answer 13

watt

Question 14

Which of the following does not affect the force of friction?

Answer 14

area in contact

Question 15

Under ideal conditions, a machine’s work output is ? its work input.

Answer 15

equal to

Question 16

If a moving walkway is going west at 50 cm/s, what is the total velocity of a man on the walkway who walks east at 60 cm/s (relative to the walkway)?

Answer 16

10 cm/s east

Question 17

The “quantity of motion” of an object, equal to the product of the object’s mass and velocity, is?

Answer 17

momentum

Question 18

For every action there is an equal and opposite reaction

Answer 18

3rd law of motion

Question 19

States the relationship between the hypotenuse and legs of a right triangle.

Answer 19

Pythagorean theorem

Question 20

The velocity of an object does not change unless the object is acted upon by an external force.

Answer 20

1st law of motion

Question 21

Any two objects attract each other with a force that depends on their masses and the distance between them

Answer 21

law of universal gravitation

Question 22

When the overall external force acting on a system is zero, the momentum of the whole system remains constant

Answer 22

law of conservation of momentum

Question 23

What is defined as distance traveled in a given time?

Answer 23

speed

Question 24

Name the resistance arising to an object’s motion through a fluid or across a surface.

Answer 24

friction

Question 25

A man is attempting to push a mule into a fenced area. He exerts 225 N of force on the animal for 20 min., but the mule does not budge. How muck work has the man done?

Answer 25

none

Question 26

What term refers to a single vector showing the combined effect of two or more vectors?

Answer 26

resultant

Question 27

What term refers to the gravitational force exerted on an object near the surface of the earth or any celestial body?

Answer 27

gravity

Question 28

What is the SI unit of force?

Answer 28

newton

Question 29

What is the name for the distance between the ridges on a screw?

Answer 29

pitch

Question 30

What term refers to the branches of physics developed before the 20th century?

Answer 30

classical physics

Question 31

Combination of fixed and movable pulleys

Answer 31

block and tackle

Question 32

"circular lever"

Answer 32

wheel and axle

Question 33

Sloping surface that allows an object to be raised without lifting it straight up

Answer 33

inclined plane

Question 34

Special form of inclined plane that modifies force and directs it to the side

Answer 34

wedge

Question 35

Resembles an inclined plane wrapped around a rod

Answer 35

screw

Question 36

The rate of doing work is called time

Answer 36

power

Question 37

The branch of physics that deals with the effects of forces on matter is mechanics.

Answer 37

true

Question 38

A lever that has the input and output forces on either side of the fulcrum is a class 3 lever.

Answer 38

class 1

Question 39

A measure of how well a machine converts input work into output work is the machine's IMA

Answer 39

efficiency

Question 40

Velocity is a vector quantity

Answer 40

true

Question 41

The thrust of a rocket is an example of the third law of motion

Answer 41

true

Question 42

The distance between a lever's fulcrum and the input force is the length of the input distance.

Answer 42

input arm

Question 43

Two vectors that are either in the same direction or in opposite directions are collinear

Answer 43

true

Question 44

The type of friction that affects moving objects is static friction

Answer 44

kinetic

Question 45

free-fall distance

Answer 45

d = 1/2gt2

Question 46

Pythagorean theorem

Answer 46

a2 + b2 = c2

Question 47

Average speed

Answer 47

s = d/t

Question 48

Power

Answer 48

P = W/t

Question 49

Multiplication of force by a machine when friction is negligible

Answer 49

IMA = di/do

Question 50

Average velocity

Answer 50

v = trianglex/t

Question 51

Newton's second law of motion

Answer 51

F = ma

Question 52

Law of universal gravitation

Answer 52

F = G(m1m2/d2)

Question 53

How much work does an elevator do in lifting a 600 N person 40 m?

Answer 53

Use W = Fd F = lifting power d = distance traveled

Question 54

What is the average acceleration of a car that accelerates from 10 m/s forward to 20 m/s forward in 5.0 s?

Answer 54

Use a = vf - vi/t vf = increased forward vi = first forward t = time to move forward

Question 55

Which has more momentum: a 20,000 kg cement truck traveling at 5 m/s or a 1000 kg race car traveling at 90 m/s?

Answer 55

Use p = mv; use one for the truck and one for the car m = weight of vehicle v = how fast the vehicle was moving