Deck 5: Newtons Third Law of Motion: Action and Reaction

Question 1

The winner in a tug-of-war exerts the greatest force on

A)the opponent.
B)his or her end of the rope.
C)the ground.

Answer 1

the ground.

Question 2

For every action force, there must be a reaction force that

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

Answer 2

is equal in magnitude.

Question 3

To say there is no such thing as only one force means

A)there must also be a corresponding reaction force.
B)other forces, perhaps not evident, are there.
C)gibberish.

Answer 3

there must also be a corresponding reaction force.

Question 4

When you drop a rubber ball on the floor it bounces back. The force exerted on the ball to produce bouncing is by the

A)ball.
B)floor.
C)need more information

Question 5

One end of a rope is pulled with 100 N, while the opposite end also is pulled with 100 N. The tension in the rope is

A)0 N.
B)50 N.
C)100 N.
D)200 N.

Question 6

When you rub your hands together, you

A)can push harder on one hand than the other.
B)cannot push harder on one hand than the other.
C)need more information

Question 7

A pair of action-reaction forces always

A)act on the same object.
B)occur simultaneously.
C)comprise a pair of interactions.
D)all of the above
E)none of the above

Question 8

A fast-moving missile soaring overhead possesses

A)speed.
B)force.
C)both of these
D)neither of these

Question 9

Arnold Strongman and Suzie Small each pull very hard on opposite ends of a 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.

Question 10

Your friend says that the heavyweight champion of the world cannot exert a force of 50 N on an isolated piece of tissue paper with his best punch. You

A)agree that it can't be done.
B)have reservations about this assertion.
C)disagree, for a good punch easily delivers this much force.

Question 11

You cannot exert a force on a wall

A)if the wall resists.
B)unless you put your mind to it.
C)unless the wall simultaneously exerts the same amount of force on you.

Question 12

When a karate chop breaks a board with a 3000-N blow, the amount of force that acts on the hand is

A)zero.
B)1500 N.
C)3000 N.
D)6000 N.

Question 13

When a skateboarder pushes on a wall,

A)an interaction occurs between the skateboarder and the wall.
B)the wall pushes on the skateboarder.
C)such a push couldn't happen unless the wall pushed on the skateboarder.
D)all the above
E)none of the above

Question 14

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

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

Question 15

As a ball bounces from a floor, its acceleration off the floor between bounces is

A)significantly less than g.
B)g.
C)slightly more than g.
D)significantly more than g.

Question 16

Harry pulls on the end of a spring attached to a wall. The reaction to Harry's pull on the spring is

A)the wall pulling oppositely on the spring.
B)the spring pulling on Harry.
C)both the wall and the spring pulling on Harry.
D)none of the above

Question 17

When you walk, you push on the floor to the left and the floor

A)also pushes on you to the left.
B)pushes you to the right.
C)both of these simultaneously.
D)can only wish it could push on you.
E)none of the above

Question 18

When a boxer hits a punching bag, the strength of his punch depends on how much force the bag can

A)endure.
B)exert on the boxer's fist.
C)soften.

Question 19

A piece of rope is pulled by two people in a tug-of-war. Each exerts a 400-N force. What is the tension in the rope?

A)zero
B)400 N
C)600 N
D)800 N
E)none of the above

Question 20

Action and reaction pairs of forces

A)always act simultaneously.
B)may or may not act simultaneously.
C)are independent of time.

Question 21

When a baseball player bats a ball with a force of 1000 N, the reaction force that the ball exerts against the bat is

A)less than 1000 N.
B)more than 1000 N.
C)1000 N.
D)need more information

Question 22

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

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

Question 23

Neglecting air resistance, once a tossed ball leaves your hand

A)no further forces act on it.
B)only the force due to gravity acts on it.
C)inertia becomes the force acting on it.
D)your tossing force remains while the ball goes upward.
E)your tossing force remains until it comes to a stop.

Question 24

The force exerted on the tires of a car that directly accelerate it along a road is exerted by the

A)engine.
B)tires.
C)air.
D)road.
E)none of the above

Question 25

The force that accelerates the orange and apple system featured in your textbook is actually supplied by the

A)apple.
B)orange.
C)floor.

Question 26

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

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

Question 27

When a tennis racquet hits a ball,

A)the racquet loses as much speed as the ball gains.
B)the ball is set in motion with the same speed of the racquet upon contact.
C)the ball hits the racquet.
D)all of the above

Question 28

A player hits a ball with a bat. If action is the force of the bat against the ball, reaction is the

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

Question 29

A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle that undergoes the greatest change in velocity will be the

A)Volkswagen.
B)Mack truck.
C)same for both.

Question 30

The lift experienced by a helicopter involves an action-reaction pair of forces between the

A)helicopter blades and the air.
B)mass of the helicopter and Earth's mass.
C)weight of the helicopter and atmospheric pressure.
D)motion of the helicopter relative to the ground below.
E)any or all of the above

Question 31

When a ball falls downward, it may have a net force

A)equal to its weight.
B)of zero.
C)equal to its weight minus air drag.
D)any of the above
E)none of the above

Question 32

The attraction between Earth and Sydney is equal to her weight. The reaction to Earth's pull on Sydney is

A)Sydney pushing against Earth's surface.
B)the support of Earth's surface on Sydney.
C)Sydney's pull on Earth.
D)none of the above

Question 33

The emphasis of the orange-and-apple sequence in your textbook is

A)defining systems.
B)actions equal reactions.
C)forces produce accelerations.
D)friction is a force.
E)mass is not a force.

Question 34

A player catches a ball. If action is the force of the ball against the player's glove, reaction is the

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

Question 35

A pair of air pucks on an air table are set in motion when a compressed spring between them is released. If one puck moves with twice the speed of the other, then its mass is

A)half the mass of the other.
B)the same mass as the other.
C)twice the mass as the other.
D)need more information

Question 36

To produce an acceleration to a system there

A)must be a net force on the system.
B)may or may not be a net force on the system.
C)must be acceleration outside the system also.

Question 37

Joshua is attracted toward Earth by a 500-N gravitational force. The Earth is attracted toward Joshua with a force of

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

Question 38

As a ball falls, the action force is the Earth's pull on the ball. The reaction force is the

A)air resistance acting against the ball.
B)acceleration of the ball.
C)ball's pull on Earth.
D)none of the above

Question 39

While you stand on the floor you are pulled downward by gravity, and supported upward by the floor. Gravity pulling down and the support force pushing up

A)make an action-reaction pair of forces.
B)do not make an action-reaction pair of forces.
C)need more information

Question 40

An automobile and a golf cart traveling at the same speed collide head-on. The impact force is

A)greater on the automobile.
B)greater on the golf cart.
C)the same for both.

Question 41

A vertical vector of 3 units combined with a horizontal vector of 4 units has a resultant of

A)1 unit.
B)5 units.
C)7 units.

Question 42

When a cannonball is fired from a cannon, which undergoes the greater acceleration?

A)the cannonball
B)the recoiling cannon
C)both the same

Question 43

Nellie Newton pulls her sled by a rope that is 45° to the horizontal. The horizontal and vertical components of force are

A)equal in magnitude.
B)each about 0.7 times the force she exerts on the rope.
C)both of these
D)neither of these

Question 44

When a rocket forces exhaust gases downward, the exhaust gases

A)as the name implies, soon exhaust their influence.
B)play no further role in the motion of the rocket.
C)exert an upward force on the rocket.

Question 45

The force due to gravity that acts on a block of ice that slides down an icy ramp

A)remains equal to mg at all angles.
B)decreases as the slope of the ramp increases.
C)becomes greatest when the ramp is vertical.

Question 46

Nellie's weight and normal force usually have the same magnitude when she stands on a

A)horizontal surface.
B)inclined surface.
C)either a horizontal or inclined surface.

Question 47

Art museums use weaker wires than those used in homes because paintings in museums

A)are suspended by pairs of vertical wires.
B)are usually lighter in weight.
C)are more firmly attached.

Question 48

Earth pulls on the Moon, and the Moon pulls on Earth, which tells us that

A)these two pulls comprise an action-reaction pair.
B)both Earth and Moon circle a common point.
C)more massive objects pull harder.
D)all of the above

Question 49

A pair of toy freight cars, one twice the mass of the other, fly apart when a compressed spring that joins them is released. Acceleration will be greater for the

A)heavier car.
B)lighter car.
C)same on each.

Question 50

If vertically falling rain makes slanted 45° streaks on the side windows of a moving car, the speed of the car

A)is less than the speed of the falling drops.
B)equals the speed of the falling drops.
C)exceeds the speed of the falling drops.
D)need more information

Question 51

A pair of toy freight cars, one twice the mass of the other, fly apart when a compressed spring that joins them is released. The spring exerts the greater force on the

A)heavier car.
B)lighter car.
C)same on each.

Question 52

When Nellie hangs suspended from a pair of ropes that are not vertical, the tension in each rope is

A)less than half her weight.
B)half her weight.
C)more than half her weight.
D)her weight.

Question 53

An astronaut of mass 70 kg weighs 700 N on Earth's surface. His weight on the surface of Mars, where the acceleration due to gravity is 3.7 m/s², would be about

A)the same as on Earth.
B)130 N.
C)260 N.
D)370 N.
E)none of the above

Question 54

The force with which Earth pulls on the Moon is

A)somewhat greater than Moon's pull on Earth.
B)the only force acting between Earth and Moon.
C)equal in magnitude to the force that Moon pulls on Earth.

Question 55

The normal force that acts on a block of ice that slides on a ramp

A)is equal to mg at all angles.
B)decreases as the slope of the ramp increases.
C)becomes greatest when the ramp is vertical.

Question 56

A shoe on an inclined surface barely remains at rest when friction equals the

A)weight mg of the shoe.
B)component of mg perpendicular to the surface.
C)component of mg parallel to the surface.
D)none of the above

Question 57

The force that propels a cannonball when fired from a cannon is

A)huge compared to the recoil force on the cannon.
B)equal and opposite to the force the ball exerts on the cannon.
C)in some cases, equal and opposite to the force the ball exerts on the cannon.

Question 58

You stand on your skateboard and exert a 50-N push on the wall next to you. If your mass is 60 kg you'll momentarily accelerate from the wall at about

A)0.08 m/s².
B)0.8 m/s².
C)8.0 m/s².
D)none of the above

Question 59

A 10-unit vector at 60° from the vertical has a vertical component with a magnitude

A)less than 10 units.
B)10 units.
C)greater than 10 units.

Question 60

Two equal-size vectors at right angles to each other have a resultant that is

A)equal to that of either vector.
B)√2 the length of either vector.
C)twice the length of either vector.

Question 61

Nellie tosses a ball upward at an angle. Neglecting air resistance, the horizontal component of the initial velocity

A)decreases with time.
B)remains constant.
C)increases with time.

Question 62

A pair of equal-length vectors at right angles to each other have a resultant. If the angle between the vectors is less than 90°, their resultant is

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

Question 63

Nellie tosses a ball upward at an angle. Neglecting air resistance, the vertical component of the initial velocity

A)decreases with time to reach the top.
B)remains constant.
C)increases with time to reach the top.

Question 64

As the sloped surface supporting a shoe becomes steeper

A)the shoe's weight mg remains unchanged.
B)the normal force becomes less.
C)friction needed to keep it at rest increases.
D)all of the above
E)none of the above

Question 65

A pair of equal-length vectors at right angles to each other have a resultant. If the angle between the vectors is greater than 90°, their resultant is

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

Question 66

When Monkey Mo is suspended at rest by holding a rope with one hand and the side of his cage with the other, all the force vectors that act on him

A)have equal magnitudes.
B)cancel except for his weight vector, mg.
C)have a vector sum of zero.

Question 67

An airplane travels at 141 km/h toward the northeast. What is its component of velocity due north?

A)41 km/h
B)100 km/h
C)110 km/h
D)141 km/h

Question 68

The airspeed of an airplane is 200 km/h. When it is caught in a 200-km/h crosswind, its speed across the ground below is

A)0 km/h.
B)200 km/h.
C)283 km/h.
D)400 km/h.
E)1600 km/h.

Question 69

A river 100 m wide flows due south. A boat that goes 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat crosses in

A)50 s.
B)100 s.
C)141 s.
D)200 s.

Question 70

Three kids pull on a toy. Kim pulls with a force of 30 N north, Jim pulls with a force of 30 N south, and Tim pulls with a force of 15 N east. The acceleration of the toy is

A)10 m/s².
B)15 m/s².
C)33 m/s²
D)need more information

Question 71

A river 100 m wide flows due south at 1 m/s. A boat that goes 1 m/s relative to the water leaves the west bank. To land at a point due east of its starting point, the boat must be pointed

A)northeast.
B)east.
C)southeast.
D)nowhere-it can't be done.