Deck 4: Newtons Laws of Motion

Question 1

A rock is thrown vertically into the air. At the very top of its trajectory the net force on it is

A) more than its weight.
B) almost equal to its weight.
C) less than its weight.

Answer 1

almost equal to its weight.

Question 2

Wherever the is an action force, there must be a reaction force which

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

Answer 2

is exactly equal in magnitude.

Question 3

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

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

Answer 3

6 N.

Question 4

Joe pushes Bill, who is asleep. Bill

A) pushes Joe immediately, but not as hard.
B) does not push even after he wakes up.
C) will inevitably push Joe when he wakes.
D) pushes Joe equally hard even without waking up.

Question 5

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 5000 N
B) about 25,000 N
C) about 500 N
D) aAbout 2500 N
E) none of these

Question 6

A pair of tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the

A) lead-filled ball.
B) regular ball.
C) same for both.

Question 7

An object released from rest on another planet requires one second to fall a distance of 6 meters. What is the acceleration in meters per second per second due to gravity on this planet?

A) 3
B) 12
C) 6
D) 15
E) none of these

Question 8

When you relax at rest with your left foot one bathroom and your right foot on a similar scale, each of the scales will

A) indicate exactly half your weight.
B) indicate different values that will equal your weight when added together.
C) indicate part of your total weight but not necessarily half of it.
D) Any of the above may be correct.

Question 9

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) 800
C) 110
D) 880
E) can't be solved without the mass of the car

Question 10

Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because

A) the weight of the car is independent of gravity.
B) the mass of the car is independent of gravity.
C) Nonsense! A car is much more easily accelerated on the moon than on the Earth.

Question 11

In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the

A) Earth.
B) planet Jupiter.
C) moon.

Question 12

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is

A) the same.
B) less.
C) more.

Question 13

A 1-kg ball is thrown at 10 m/s straight upward. Neglecting air resistance, the net force that acts on the stone when it is halfway to the top of its path is about

A) 7.5 N.
B) 1 N.
C) 1/2 N.
D) 5 N.
E) 10 N.

Question 14

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

Question 15

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much

A) inertia.
B) volume.
C) mass.
D) all of these
E) none of these

Question 16

A 1-kg mass at the earth's surface weighs

A) 9.8 N.
B) 10.8 N.
C) 4.9 N.
D) 1 N.
E) none of these

Question 17

A automobile and a baby carriage traveling at the same speed collide head-on. The impact force is

A) greater on the baby carriage.
B) greater on the automobile.
C) the same for both.

Question 18

Two factors that greatly affect air resistance on falling objects are the

A) size and weight of the object.
B) size and mass of the object.
C) size and speed of the object.

Question 19

A skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on the diver is then

A) 500 N.
B) 90 N.
C) 250 N.
D) 410 N.
E) none of these

Question 20

Suppose a particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a second force of 10 N in the opposite direction from the first force. The particle with both forces acting on it

A) continues at the speed it had when it encountered the second force.
B) is brought to a rapid halt.
C) decelerates gradually to a halt.
D) theoretically tends to accelerate toward the speed of light.
E) none of these

Question 21

A ball is thrown vertically into the air. Because of air resistance, its speed when it returns to its starting level compared with its initial speed is

A) less.
B) more.
C) the same.

Question 22

A vehicle that weighs 4000 N on the surface of the Earth is travelling in outer space at a speed of 200 m/s. The smallest constant force that must be applied to stop it in 20 seconds is

A) 4000 N.
B) 40 N.
C) 400 N.
D) 20 N.
E) more than 4000 N.

Question 23

A heavy rock and a light rock of the same size are falling through the air from a tall building. The one that encounters the greatest air resistance is the

A) light rock.
B) heavy rock.
C) same for both.

Question 24

A large and a small person wish to parachute at equal terminal velocities. The larger person will have to

A) get a larger parachute.
B) jump lightly.
C) jump first from the plane.
D) pull upward on the supporting strands to decrease the downward net force.

Question 25

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

Question 26

A car traveling at 100 km/hr strikes an unfortunate bug and splatters it. The force of impact is

A) greater on the car.
B) greater on the bug.
C) the same for both.

Question 27

A man weighing 800 N stands at rest on two bathroom scales so that his weight is distributed evenly over both scales. The reading on each scale is

A) 1600 N.
B) 800 N.
C) 400 N.
D) 200 N.
E) none of these

Question 28

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same

A) volume.
B) mass.
C) weight.
D) all of these
E) none of these

Question 29

A falling skydiver of mass 100 kg experiences 500 N air resistance. The acceleration of the skydiver is

A) 0.5 g.
B) 0.3 g.
C) 0.4 g.
D) 0.2 g.
E) more than 0.5 g.

Question 30

A ball thrown straight upward takes 10 seconds to go up and return to the ground. Because of air resistance, the time taken for the ball just to go up is

A) 5 s.
B) more than 5 s.
C) less than 5 s.

Question 31

When a woman stands at rest with both feet on a scale, it reads 500 N. When she gently lifts one foot, the scale reads

A) less than 500 N.
B) 500 N.
C) more than 500 N.

Question 32

If a non-rotating object has no acceleration, then we can say for certain that it is

A) moving at constant non-zero velocity.
B) in mechanical equilibrium.
C) at rest.
D) all of these
E) none of these

Question 33

The force of friction on a sliding object is 10 newtons. The applied force needed to maintain a constant velocity is

A) 10 N.
B) more than 10 N.
C) less than 10 N.

Question 34

If one object has twice as much mass as another object, it also has twice as much

A) acceleration due to gravity.
B) inertia.
C) velocity.
D) volume.
E) all of these

Question 35

An archer shoots an arrow. Consider the action force to be exerted by the bowstring against the arrow. The reaction to this force is the

A) arrow's push against the bowstring.
B) air resistance against the bow.
C) friction of the ground against the archer's feet.
D) combined weight of the arrow and bowstring.
E) grip of the archer's hand on the bow.

Question 36

The force exerted by the road on each tire of an accelerating car

A) is more than the combined force on all four tires on the road.
B) equals the combined force of all four tires on the road.
C) is less than the combined force of all four tires on the road.

Question 37

A heavy block at rest is suspended by a vertical rope. When the block is accelerated upward by the rope, the rope tension

A) decreases.
B) remains the same.
C) increases.

Question 38

Your car is coasting on level ground at 60 km/h and you apply the brakes until the car slows to 40 km/h. If you suddenly release the brakes now, the car tends to

A) decrease in speed if no other forces act.
B) continue moving at 40 km/h.
C) momentarily regain its higher initial speed.

Question 39

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

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

Question 40

A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass?

A) the one on the moon
B) the one on Earth
C) They have the same mass.
D) not enough information to say

Question 41

The Earth pulls on the moon. Similarly the moon pulls on the Earth, evidence that

A) larger objects pull harder.
B) the earth is larger so its pull is larger.
C) the moon is smaller so its pull is smaller.
D) these two pulls comprise an action-reaction pair.

Question 42

A 2000-kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds. The speed of the car just before the brakes were applied was

A) 45 m/s.
B) 15 m/s.
C) 1.2 m/s.
D) 30 m/s.
E) none of these

Question 43

A lightweight feather slides off a table and falls through the air until it reaches the floor. During the time of its fall,.its acceleration

A) keeps decreasing.
B) keeps increasing.
C) is sometimes zero.
D) never changes.

Question 44

Your weight is

A) a property of mechanical equilibrium.
B) equal to your mass.
C) the gravitational attraction force between you and the Earth.
D) all of these

Question 45

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) is constant.
C) increases.
D) decreases.
E) none of these

Question 46

A 1-kg rock that weighs 9.8 N is thrown straight upward at 20 m/s. Neglecting air resistance, the net force that acts on it when it is half way to the top of its path is

A) more than 9.8 N.
B) 9.8 N.
C) less than 9.8 N.

Question 47

A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time?

A) 400 m
B) 300 m
C) 200 m
D) 100 m
E) none of these

Question 48

An object maintains a constant acceleration unless there is a change in

A) the applied force.
B) the air resistance.
C) its mass.
D) any of the above

Question 49

An object is propelled along a straight-line path by a force. If the net force were doubled, the object's acceleration would be

A) half as much.
B) twice as much.
C) four times as much.
D) the same.
E) none of these.

Question 50

A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the

A) air resistance on the ball.
B) grip of the player's hand against the ball.
C) force that the ball exerts on the bat.
D) weight of the bat.
E) weight of the ball.

Question 51

A horse exerts 500 N of force on a heavy wagon. The wagon pulls back on the horse with an equal force. The wagon still accelerates because

A) these forces are not an action-reaction pair.
B) the wagon does not accelerate because these forces are equal and opposite.
C) the horse pulls on the wagon a brief time before the wagon reacts.
D) nevertheless there is still an unbalanced force on the wagon.
E) the wagon is not alive.

Question 52

A force of 1 N accelerates a mass of 1 kg at the rate of 1 m/s2. The acceleration of a mass of 2 kg acted upon by a net force of 2 N is

A) twice as much.
B) the same.
C) half as much.
D) none of these.

Question 53

A rock is thrown vertically into the air. At the top of its path, its acceleration in meters per second per second is

A) zero.
B) greater than 9.8.
C) between 0 and 9.8.
D) 9.8.

Question 54

A skydiver's terminal velocity will be greatest if she falls

A) lying flat on her back.
B) lying flat on her stomach.
C) with her parachute open.
D) head first.

Question 55

The mass of a pet turtle that weighs 10 N is

A) about 1000 kg.
B) about 100 kg.
C) about 1 kg.
D) about 10 kg.
E) none of these

Question 56

A push on a 1-kg brick accelerates it. Neglecting friction, to equally accelerate a 10-kg brick, one would have to push with

A) one tenth the amount of force.
B) just as much force.
C) 100 times as much force.
D) 10 times as much force.
E) none of these

Question 57

Two people, one twice as massive as the other, attempt a tug-of- war with 12 meters of massless rope on frictionless ice. After a brief time, they meet. The heavier person slides a distance of

A) 4 m.
B) 6 m.
C) 0 m.
D) 3 m.

Question 58

If you are driving at 20 m/s and slam on your brakes and skid at 0.5 g to a full stop, the skidding time in seconds is

A) about 5.
B) about 3.
C) about 4.
D) about 6.
E) more than 6.

Question 59

An apple weighs 1 N. When held at rest above your head, the net force on the apple is

A) 1 N.
B) 9.8 N.
C) 0 N.
D) 0.1 N.
E) none of these

Question 60

If an object's mass is decreasing while a constant force is applied to the object, the acceleration

A) decreases.
B) remains the same.
C) increases.

Question 61

The attraction of a person's body toward the Earth is called weight. The reaction to this force is

A) the person's body pushing against the Earth's surface.
B) the person's body pulling on the Earth.
C) the Earth's surface pushing against the person's body.
D) none of these.

Question 62

An coconut and a feather fall from a tree through the air to the ground below. The amount of air-resistance force is

A) greater on the feather.
B) greater on the coconut.
C) the same on each.

Question 63

A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. What is the jet's acceleration in meters per second per second when taking off?

A) 2
B) 4
C) 0.25
D) 1
E) none of these

Question 64

A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. The reaction to this force is the

A) muscular effort in the player's arms.
B) player's grip on the glove.
C) force the glove exerts on the ball.
D) friction of the ground against the player's shoes.
E) none of these

Question 65

Which has the greater mass?

A) an automobile battery
B) a king-size pillow
C) neither - both have the same

Question 66

A 10-N block and a 1-N block lie on a horizontal frictionless table. To provide them with equal horizontal acceleration, we would have to push with

A) 10 squared or 100 times as much force on the heavier block.
B) 10 times as much force on the heavier block.
C) 1/10 as much force on the heavier block.
D) equal forces on each block.
E) none of these

Question 67

A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration in meters per second per second is

A) 0.
B) 9.8.
C) 4.9.
D) infinite.
E) none of these

Question 68

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

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

Question 69

Arnold Strongman and Suzie Small each pull very hard on opposite ends of a massless rope in a tug-of-war. The greater force on the rope is exerted by

A) Arnold, of course.
B) Suzie, surprisingly.
C) both the same, interestingly enough.

Question 70

A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s . It can be stopped by applying a constant force of 20 N for

A) 2 seconds.
B) 400 seconds.
C) 4 seconds.
D) 800 seconds.
E) 80 seconds.

Question 71

Whenever the net force on an object is zero, its acceleration

A) is zero.
B) may be less than zero.
C) may be more than zero

Question 72

A bag of groceries has a mass of 10 kilograms and a weight of

A) about 1 N.
B) about 1000 N.
C) about 100 N.
D) about 10 N.
E) more than 1000 N.

Question 73

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

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

Question 74

A rocket becomes progressively easier to accelerate as it travels upward from the ground mainly because

A) the applied force on the rocket increases as burning of fuel progresses.
B) the mass of the rocket decreases as fuel is burned.
C) gravity becomes weaker with increased distance.

Question 75

Compared to the mass of a certain object on Earth, the mass of the same object on the moon is

A) zero.
B) six times as much.
C) one sixth as much.
D) the same.

Question 76

Neglecting friction, a large block of ice and a small block of ice start sliding down an incline together. The heavier block will get to the bottom

A) before the light block.
B) at the same time as the light block.
C) after the light block.

Question 77

The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is

A) one fourth.
B) the same.
C) one half.
D) one third.
E) none of these

Question 78

A 10-kilogram block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is
About

A) 25 N.
B) 10 N.
C) 50 N.
D) 5 N.
E) none of these

Question 79

A force is a vector quantity because it has both

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

Question 80

A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is

A) 10.
B) 5.
C) 1.
D) 2.
E) none of these