Exam 1

Question 1

The first estimate of the size of the moon and the first written record for the sun centered cosmos are attributed to

Answer 1

aristarchus

Question 2

When a rocket forces exhaust gases downward the exhaust gases

Answer 2

exert an upward force on the rocket

Question 3

If an apple experiences a constant net force, it will have a constant

Answer 3

acceleration

Question 4

the force of air resistance or air drag depends on

Answer 4

the speed that the object is raveling through the air and the frontal surface area

Question 5

if you throw a rock upward at a speed of 50 m/s how long until the rock reaches its peak height?

Answer 5

5 s

Question 6

Galileo taught us that if you roll a ball along a level surface it will

Answer 6

keep rolling if friction is absent

Question 7

a large heavy truck and a small baby carriage roll down a hill. neglecting friction, at the bottom of the hill, the baby carriage will likely have

Answer 7

less momentum

Question 8

when a pair of 10N forces acts on a box of candy, the net force on the box is

Answer 8

any of the above depending on the directions of forces

Question 9

a force is a vector quantity because it has both

Answer 9

magnitude and direction

Question 10

when the sun shines on the moon, the moon casts a shadow

Answer 10

• that is tapered
• at all times
• that sometimes falls on earth

Question 11

the equilibrium rule applies to

Answer 11

• objects or systems in uniform motion in a straight line

- objects or systems at rest

Question 12

you toss a ball and it makes a curved path. at the instant that the ball leaves your hand it has a velocity which has a horizontal component of 30 m/s and a vertical component of 20 m/s. how far from you does the ball land?

Answer 12

120 m

Question 13

when you are moving at constant velocity, which of the following is NOT true

Answer 13

you are experiencing a non zero acceleration

Question 14

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 state of zero acceleration first?

Answer 14

the light woman

Question 15

student A has a mass of 95 kg and student B has a mass of 77 kg. they sit in identical office chairs facing each other. student A places his bare feet on the knees of student B as shown. student A suddenly pushes outward with his feet, causing both chairs to move. during the push while the students are still in contact with one another

Answer 15

each student exerts the same amount of force on the other

Question 16

Copernicus and Aristarchus shared the view that was against Aristotelian dogman, namely that

Answer 16

the sun was the center of the cosmos and the earth moves; it orbits the sun

Question 17

the greek mathematician Eratosthenes made observations of sunlight striking water in the bottom of a well and also shadows cast in a neighboring town to find the size of

Answer 17

earth

Question 18

a freely falling watermelon falls with constant

Answer 18

acceleration

Question 19

a vehicle undergoes acceleration when it

Answer 19

• gains speed
• loses speed
• changes its direction

Question 20

which of the following is not a vector?

Answer 20

speed

Question 21

a moving van with a stone lightly glued to the midpoint of its ceiling smoothly moves at constant velocity. when the glue gives way, the stone falls and hits the floor

Answer 21

exactly below the midpoint of the ceiling

Question 22

two metal balls are the same size but one weighs twice as much as the other. the balls are dropped from the roof of a single story building at the same instant of time. the time it takes the balls to reach the ground below will be

Answer 22

about the same for both balls

Question 23

a stone dropped for the roof of a single story building to the surface of the earth

Answer 23

speeds up because of an almost constant force of gravity acting upon it

Question 24

a 10 N falling object encounters 10 N of air resistance, the net force on the object is

Answer 24

0 N

Question 25

a truck traveling 60 mph can be brought to a stop by hitting a large hay stack or it can be brought to a stop by hitting a brick wall. physics says

Answer 25

the impulse is the same either way but hitting the hay stack reduces force involved by extending the time of the impact

Question 26

which of the following is NOT a characteristic of a scientific hypothesis?

Answer 26

once proved correct by one experiment, it can never be proved wrong by any experiment

Question 27

the force with which earth pulls on the moon is

Answer 27

equal in magnitude to the force that moon pulls on earth

Question 28

if a stone falls to the bottom of a mine shaft in 6 seconds, then the depth of the shaft is about

Answer 28

180 m

Question 29

a skydiver steps from a helicopter and falls for a few seconds until terminal velocity is reached. thereafter, until he opens his parachute, his acceleration

Answer 29

is zero

Question 30

a 600 N man stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. the reading on each scale is

Answer 30

300 N

Question 31

a woman exerts a constant horizontal force on a large box. as a results, the box moves across a horizontal floor at a constant sped. the constant horizontal force applied by the woman

Answer 31

has the same magnitude as the total force which resists the motion of the box

Question 32

if a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is

Answer 32

6 m/s2

Question 33

when no force act on moving objects their paths are normally

Answer 33

straight lines

Question 34

you throw a rock upward. the speed of the rock is 30 m/s when it leaves your hand. which of the following is false?

Answer 34

at the peak of the trajectory, the acceleration due to the force of gravity on the rock is zero

Question 35

a humming bird flying at 4 km/h that gets caught in a 3 km/h crosswind has a resultant speed of about

Answer 35

5 km/h

Question 36

in physics we seek

Answer 36

to describe nature and understand its rules

Question 37

the weight of a full liter jug of water on the surface of the moon is

Answer 37

less than it is here on the surface of earth

Question 38

Aristotle believed all of the following except

Answer 38

in the absence of air resistance heavy and light objects dropped from the same height reach the ground at the same time

Question 39

if a freely falling object were equipped with a speedometer, its speed reading would increase each second by about

Answer 39

5 m/s