Deck 2: Newtons Laws of Motion

Question 1

If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in

A)a curved path.
B)an outward spiral path.
C)an inward spiral path.
D)a straight-line path.

Answer 1

D

Question 2

When dishes remain on a table when you yank the tablecloth beneath them, you're demonstrating

A)friction.
B)inertia.
C)constant motion.
D)ΣF = 0.

Answer 2

B

Question 3

How does the equilibrium rule, ΣF = 0, relate to Newton's first law of motion?

Answer 3

The equilibrium rule states Newton's first law of motion in equation form! So it relates very well. When no net force acts on an object, the motion of the object doesn't change.

Question 4

A roller coaster car at an amusement park carrying 1 passenger takes 3 min to make its ride from start to finish. Neglecting friction, a car with 5 passengers would take

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

Question 5

A sheet of paper can be pulled from beneath a box of cereal without toppling it if the paper is jerked quickly. This best demonstrates that

A)the box has no acceleration.
B)there is an action-reaction pair of forces.
C)gravity tends to hold the box secure.
D)the box has inertia.

Question 6

An object in motion tends to remain in motion

A)because of a force inside the object.
B)only when an external force acts on it.
C)without the need of a force.
D)due to their nature.

Question 7

Earth moves about 30 km/s relative to the Sun. When you jump upward in front of a wall, the wall doesn't slam into you at 30 km/s because the wall

A)has too little gravity to influence you.
B)moves in the opposite direction to you.
C)and you move at the same horizontal speed, before, during, and after your jump.
D)has negligible inertia compared with the Sun.

Question 8

Newton's second law directly involves

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

Question 9

When you drop a pencil while riding on a smoothly riding bus, why does the pencil land at the same place it would if the bus were at rest?

Question 10

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

A)continue in a circular path.
B)follow a straight-line path.
C)spiral inward.
D)fall straight downward.

Question 11

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

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

Question 12

A ball rests in the middle of a cart. When you quickly jerk the cart forward, the ball

A)hits the front of the cart.
B)hits the back of the cart.
C)remains in the middle of the cart.
D)all, depending on how quickly the cart is pulled.

Question 13

A space probe in remote outer space continues moving

A)because a force acts on it.
B)in a curved path.
C)even though no force acts on it.
D)due to gravity.

Question 14

Inside the interior of a truck that moves at constant velocity is a package that drops from the midpoint of the ceiling. The package 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 is needed
E)none of the above

Question 15

When you step off a bus moving at 10 m/s, your horizontal speed when you meet the ground is

A)zero.
B)less than 10 m/s but greater than zero.
C)about 10 m/s.
D)greater than 10 m/s.

Question 16

The net force on any object moving at constant velocity is

A)zero.
B)10 meters per second squared.
C)equal to its weight.
D)less than its weight.

Question 17

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.

Question 18

To steadily (constantly)increase the velocity of something requires a

A)steadily increasing force.
B)constant force.
C)decreasing force.
D)none of the above

Question 19

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

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

Question 20

A hockey puck slides across a frozen pond. If ice friction and air resistance are neglected, the force needed 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 21

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 is

A)1 m/s².
B)2 m/s².
C)5 m/s².
D)10 m/s².
E)none of the above

Question 22

A commercial jet has a mass of 5,000 kg and the thrust of its engine is 10,000 N. The acceleration of the jet when taking off is

A)0.5 m/s².
B)1 m/s².
C)2 m/s².
D)4 m/s².
E)none of the above

Question 23

A push on a 1-kg brick accelerates the brick. Neglecting friction, to equally accelerate a 10-kg brick requires the force to be

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

Question 24

A 10-kg block is pushed across a horizontal surface with a horizontal force of 30 N against a friction force of 10 N. The acceleration of the block is

A)1 m/s².
B)2 m/s².
C)5 m/s².
D)10 m/s².
E)none of the above

Question 25

A block is dragged at constant velocity 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)not enough information

Question 26

What applied horizontal 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 27

A given net force propels an object along a straight-line path. If the net force were doubled, its acceleration would

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

Question 28

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 29

If an object's mass decreases while a constant force acts on it, the acceleration

A)decreases.
B)remains the same.
C)increases.
D)will be zero.

Question 30

A car has a certain maximum acceleration. When it tows another twice-as-massive car its maximum acceleration is

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

Question 31

A given net force propels an object along a straight-line path by a force. If the mass were doubled, its acceleration would

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

Question 32

A tow truck exerts a force of 3000 N on a car that accelerates at 2 m/s². The mass of the car must be

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

Question 33

A force of 1 N accelerates a 1-kg mass at 1 m/s². The acceleration of a 2-kg mass 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 34

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

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

Question 35

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

A)0.3 m/s²
B)3.0 m/s²
C)10 m/s²
D)30 m/s²
E)300 m/s²

Question 36

A 10-kg block is pushed across a friction-free horizontal surface with a horizontal force of 20 N. The acceleration of the block is

A)1 m/s².
B)2 m/s².
C)5 m/s².
D)10 m/s².
E)none of the above

Question 37

A particle is being accelerated through space by a 10-N force. Suddenly the particle encounters a head-on second force of 10 N in the opposite direction. 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 38

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 other forces act or not.

Question 39

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 40

A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. The acceleration of the jet when taking off is

A)0.5 m/s².
B)1 m/s².
C)2 m/s².
D)4 m/s².
E)none of the above

Question 41

A heavy rock and a light rock in free fall have the same acceleration. Both rocks have the same acceleration because

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

Question 42

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

A)the same as that of the 1-kg book.
B)5 times as much as for the 1-kg book.
C)10 times as much as for the 1-kg book.
D)zero.

Question 43

When you toss a ball upward, after the ball leaves your hand

A)the force of your hand moves it up and gradually changes direction.
B)the upward force changes direction at the top of the path.
C)we see that force and velocity are essentially the same thing.
D)none of the above

Question 44

Drop a rock from a 5-m height and it accelerates at 10 m/s² and strikes the ground in

A)1/5 s.
B)1/2 s.
C)1 s.
D)2 s.

Question 45

A math book and a science book 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 46

How many forces act on an upwardly tossed coin when it gets to the top of its path?

A)one; the force due to gravity
B)two; gravity and the force in the coin itself
C)three; gravity, the coin's internal force, and a turnaround force
D)none of the above

Question 47

A rock is thrown vertically upward. At the top of its straight-line path the force acting on it is

A)zero.
B)only the force due to gravity.
C)due to air resistance.
D)both due to gravity and air resistance.

Question 48

A ball tossed vertically upward reaches its highest point and then falls back to its starting point. During this up-and-down motion the acceleration of the ball is always

A)in the direction of motion.
B)opposite its velocity.
C)directed upward.
D)directed downward.

Question 49

A rock is thrown vertically upward. At the top of its straight-line path, its velocity is

A)0 m/s.
B)10 m/s.
C)between 0 m/s² and 10 m/s².
D)greater than 10 m/s.
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 heavy object and a light object in a vacuum are dropped at the same time from rest. 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 52

When you toss a coin straight up, it moves upward, turns around, and drops. During this time the acceleration of the coin is

A)upward and constant.
B)downward and constant.
C)first decreasing, then increasing.
D)zero throughout its up and down motion.

Question 53

After a ball tossed upward leaves your hand, the force of gravity on it

A)no longer acts.
B)gradually diminishes.
C)gradually increases.
D)remains constant.
E)changes direction.

Question 54

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)5 times as much as the force on the 1-kg book.
C)10 times as much as the force on the 1-kg book.
D)zero.

Question 55

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 56

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

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

Question 57

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

A)0 m/s².
B)10 m/s².
C)between 0 m/s² and 10 m/s².
D)greater than 10 m/s².
E)none of the above

Question 58

If you are learning to juggle it would be good to slow the ball's acceleration. You can do this by using

A)lighter balls.
B)heavier balls.
C)more balls.
D)none of the above

Question 59

A ball is thrown upward and caught when it comes back down. When air resistance affects the ball, compared with the initial upward speed, the speed when caught is

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

Question 60

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

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

Question 61

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

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

Question 62

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

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

Question 63

When a 500-N parachutist opens his chute and experiences 800 N of air resistance, the net force on him is

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

Question 64

A skydiver steps from a helicopter and falls for 5 s before reaching 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 65

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

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

Question 66

The acceleration of a rocket increases 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 fuel is burned.
C)the mass of the rocket decreases as fuel is burned.

Question 67

A large and a small person wish to parachute at equal terminal velocities. The large person should

A)jump first.
B)jump lightly.
C)pull upward on the supporting strands to decrease the downward net force.
D)get a larger parachute.
E)none of the above

Question 68

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 69

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

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

Question 70

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

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

Question 71

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

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

Question 72

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 the

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

Question 73

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

A)acceleration.
B)speed.
C)both
D)neither

Question 74

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

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

Question 75

The air resistance of falling is greatly affected by an object's frontal area and

A)mass.
B)weight.
C)speed.

Question 76

When a rock thrown straight up reaches the exact top of its path, its velocity is

A)zero and its acceleration is zero.
B)zero and its acceleration is 10 m/s².
C)about 10 m/s and its acceleration is zero.
D)about 10 m/s and its acceleration is 10 m/s².

Question 77

When a skydiver of mass 100 kg experiences air resistance of 400 N, her acceleration is

A)0.2g.
B)0.4g.
C)0.5g.
D)0.6g.
E)more than 0.6g.

Question 78

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

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

Question 79

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 is

A)0 m/s².
B)5 m/s².
C)10 m/s².
D)infinite.
E)none of the above

Question 80

When an object falls through the air and gains velocity, the net force actually

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