Deck 3: Newtons Laws of Motion

Question 1

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to

A)continue to follow a circular path.
B)follow a straight-line path.

Answer 1

B

Question 2

Strange as it may seem, it is just as hard to accelerate a car on the Moon as it is to accelerate the same car on Earth. This is because the

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

Answer 2

A

Question 3

On the surface of Jupiter, where the acceleration due to gravity is about three times that of Earth, a 100-kg rock would have a mass of about

A)100 kg.
B)300 kg.
C)600 kg.
D)900 kg.

Answer 3

A

Question 4

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

A)quadruple.
B)double.
C)stay the same.
D)halve.
E)none of the above

Question 5

A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly.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 no acceleration.
B)there is an action-reaction pair of forces.
C)gravity tends to hold the milk carton secure.
D)the milk carton has inertia.
E)none of the above

Question 6

A truck is moving at constant velocity. Inside the storage compartment, a rock is dropped from the midpoint of the ceiling and strikes the floor below. The rock hits the floor

A)exactly below the midpoint of the ceiling.
B)ahead of the midpoint of the ceiling.
C)behind the midpoint of the ceiling.
D)more information needed to solve this problem
E)none of the above

Question 7

According to Newton's Law of Inertia, the result of walking around much of the day is similar to tightening the head of a hammer when its handle hits a solid surface so that we are actually a little bit shorter in the

A)morning.
B)evening.
C)no difference, really

Question 8

An empty roller coaster car at an amusement park takes 3 min to make its ride from start to finish. Neglecting friction, a fully loaded car would take

A)less than 3 min.
B)more than 3 min.
C)3 min.

Question 9

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

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

Question 10

On the surface of Jupiter, where the acceleration due to gravity is about three times that of Earth, a 100-kg rock would have a weight of about

A)1000 N.
B)3000 N.
C)6000 N.
D)9000 N.

Question 11

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

Question 12

If you are carrying a heavy bag of groceries and bang your hand against the wall, the concept that most explains why you are hurt is

A)inertia.
B)gravity.
C)acceleration.
D)resistance.
E)none of the above

Question 13

An object is propelled along a straight-line path in space by a force. If the mass of the object somehow becomes twice as much, its acceleration

A)quadruples.
B)doubles.
C)stays the same.
D)halves.
E)none of the above

Question 14

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)0 N.
B)equal to the weight of the puck.
C)the weight of the puck divided by the mass of the puck.
D)the mass of the puck multiplied by 10 m/s2.
E)none of the above

Question 15

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is

A)the same as the force on the 1-kg book.
B)ten times as much as the force on the 1-kg book.
C)zero.

Question 16

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

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

Question 17

An object maintains its state of motion because it has

A)mass.
B)weight.
C)speed.
D)acceleration.
E)all of the above

Question 18

The weight of 0.6 kg of salami is about

A)0)06 N.
B)6)0 N.
C)60 N.
D)600 N.

Question 19

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

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

Question 20

A force is a vector quantity because it has both

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

Question 21

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 force of 2 N is

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

Question 22

The force required to maintain an object at a constant velocity in free space is equal to

A)zero.
B)the mass of the object.
C)the weight of the object.
D)the force required to stop it.
E)none of the above

Question 23

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 of the first force. The particle with both forces acting on it

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

Question 24

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

Question 25

A girl pulls on a 10-kg wagon with a constant force of 30 N. What is the wagon's acceleration in meters per second squared?

A)0)3
B)3)0
C)10
D)30
E)300

Question 26

An object following a straight-line path at constant speed

A)has a net force acting upon it in the direction of motion.
B)has zero acceleration.
C)must be moving in a vacuum or in the absence of air drag.
D)has no forces acting on it.
E)none of the above

Question 27

An apple weighs 1 N. The magnitude of net force on the apple when it is in free-fall is

A)0 N.
B)0)1 N.
C)1 N.
D)10 N.
E)none of the above

Question 28

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

A)1/2 N.
B)1 N.
C)5 N.
D)7)5 N.
E)10 N.

Question 29

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

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

Question 30

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

A)less than its weight.
B)more than its weight.
C)its weight.

Question 31

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

A)0 N.
B)0)1 N.
C)1 N.
D)10 N.
E)none of the above

Question 32

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)after the light block.
C)at the same time as the light block.

Question 33

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

A)equal forces on each block.
B)10 times as much force on the heavier block.
C)10 squared or 100 times as much force on the heavier block.
D)one-tenth as much force on the heavier block.
E)none of the above

Question 34

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

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

Question 35

If the mass of an object does not change, a constant net force on the object produces constant

A)velocity.
B)acceleration.
C)both A and B
D)none of the above

Question 36

A car has a mass of 1000 kg and accelerates at 2 m/s2. What is the magnitude of the force exerted on the car?

A)500 N
B)1000 N
C)1500 N
D)2000 N
E)none of the above

Question 37

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

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

Question 38

A tow truck exerts a force of 3000 N on a car, accelerating it at 2 m/s2. What is the mass of the car?

A)500 kg
B)1000 kg
C)1500 kg
D)3000 kg
E)none of the above

Question 39

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

A)about 0.
B)about 10.
C)between 0 and 10.
D)greater than 10.
E)none of the above

Question 40

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

A)0)25
B)1
C)2
D)4
E)none of the above

Question 41

A 1-kg rock that weighs 10 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)less than 10 N.
B)10 N.
C)more than 10 N.

Question 42

A 10-kg 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 squared is

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

Question 43

Two books are tied together with a length of string. With the string taut, one book is pushed off the edge of a table. As it falls, the other book is dragged horizontally across the table surface. With no friction, acceleration of the books is

A)zero.
B)g/2.
C)g)
D)a value between zero and g.
E)a value that could be greater than g.

Question 44

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

A)1)2 m/s.
B)15 m/s.
C)30 m/s.
D)45 m/s.
E)none of the above

Question 45

An object released from rest on another planet requires 1 s to fall a distance of 6 m. What is the acceleration in meters per second squared due to gravity on this planet?

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

Question 46

The mass of a pet turtle that weighs 10 N is about

A)1 kg.
B)10 kg.
C)100 kg.
D)1000 kg.
E)none of the above

Question 47

What horizontal applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight?

A)600 N
B)1600 N
C)2000 N
D)2400 N
E)none of the above

Question 48

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

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

Question 49

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

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

Question 50

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

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

Question 51

A skydiver of mass 100 kg experiences air resistance of 500 N, and an acceleration of about

A)0)2g.
B)0)3g.
C)0)4g.
D)0)5g.
E)more than 0.5g.

Question 52

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 about

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

Question 53

A speeding truck slams on its breaks and skids to a stop. If the truck were heavily loaded so it had twice the total mass, the skidding distance would be

A)half as far.
B)one-and-a-half times as far.
C)2 times as far.
D)4 times as far.
E)the same.

Question 54

A heavy rock and a light rock in free-fall have the same acceleration. The reason the heavy rock doesn't have a greater acceleration is that the

A)force due to gravity is the same on each.
B)air resistance is always zero in free fall.
C)inertia of both rocks is the same.
D)ratio of force to mass is the same.
E)none of the above

Question 55

A 100-kg automobile enters a freeway onramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 s. How far does the automobile travel during that time?

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

Question 56

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

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

Question 57

A bag of groceries has a mass of 10 kg and a weight of about

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

Question 58

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

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

Question 59

Suppose you're coasting in a car at 60 km/h and apply the brakes until you slow to 40 km/h. When you suddenly release the brake, the car tends to

A)momentarily regain its higher initial speed.
B)continue moving at 40 km/h in the absence of forces.
C)decrease in speed whether or not other forces act.

Question 60

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

A)about 500 N
B)about 2500 N
C)about 5000 N
D)about 25,000 N
E)none of the above

Question 61

A large person 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)pull upward on the supporting strands to decrease the downward net force.
D)jump first from the plane.
E)none of the above

Question 62

A skydiver jumps from a high-flying plane. As the velocity of her fall increases, the acceleration

A)increases.
B)decreases.
C)remains unchanged regardless of air resistance.

Question 63

If you drop an object, it will accelerate downward at a rate of about 10 m/s2. If you instead throw it downward, its acceleration (in the absence of air resistance)will be

A)less than 10 m/s2.
B)10 m/s2.
C)greater than 10 m/s2.

Question 64

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 squared is

A)less than g.
B)g)
C)more than g.

Question 65

When a falling object has reached its terminal velocity, its acceleration is

A)constant.
B)zero.
C)g)

Question 66

A 500-N parachutist opens his chute and experiences an air resistance force of 800 N. The net force on the parachutist is

A)300 N downward.
B)500 N downward.
C)800 N downward.
D)300 N upward.
E)500 N upward.

Question 67

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 light woman
B)the heavy man
C)both should at the same time
D)not enough information

Question 68

Two objects of the same size but unequal weights are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be

A)the lighter object.
B)the heavier object.
C)both hitting at the same time
D)not enough information

Question 69

If an object falls with constant acceleration, the velocity of the object must

A)be constant also.
B)continually change by the same amount each second.
C)continually change by varying amounts, depending on its speed.
D)continually decrease.
E)none of the above

Question 70

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

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

Question 71

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

A)elephant.
B)feather.
C)is the same on each

Question 72

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 squared is

A)0)
B)5)
C)10.
D)infinite.
E)none of the above

Question 73

A skydiver steps from a helicopter and falls for 5 s before reaching her terminal velocity. During this 5-s interval, her acceleration

A)is constant.
B)increases.
C)decreases.
D)is zero.
E)none of the above

Question 74

When an object falls through the air, its velocity increases and its acceleration

A)increases.
B)decreases.
C)remains the same whether in the air or in a vacuum.

Question 75

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

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

Question 76

A heavy object and a light object are dropped at the same time from rest in a vacuum. The heavier object reaches the ground

A)sooner than the lighter object.
B)at the same time as the lighter object.
C)later than the lighter object.

Question 77

A falling object that has reached its terminal speed continues to gain

A)acceleration.
B)speed.
C)both A and B
D)neither A nor B

Question 78

A pair of tennis balls fall through the air from a tall building. One ball is ordinary and the other is filled with lead pellets. Air resistance just before they hit the ground is actually greater for the

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

Question 79

When a rock thrown straight upward gets to the exact top of its path, its velocity is

A)zero and its acceleration is zero.
B)zero and its acceleration is about 10 m/s2.
C)about 10 m/s and its acceleration is zero.
D)about 10 m/s and its acceleration is about 10 m/s2.
E)none of the above

Question 80

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

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