Choose the best answer to each question and write the appropriate letter in the space provided.

1) Whenever an object exerts a force on another object, the second object exerts a force of the same magnitude, but in the opposite direction to that of the first object.
A) Always true
B) Sometimes true
C) Always false

2) A high school student hits a nail with a hammer. During the collision, there is a force __________.
A) on the hammer but not on the nail.
B) on the nail but not on the hammer.
C) on the nail and also on the hammer.

3) Forces always occur __________.
A) by themselves.
B) as single quantities.
C) in pairs.
D) in triplets.

4) An archer shoots an arrow. Consider the action force to be the bow string against the arrow. The reaction to this force is the __________.
A) weight of the arrow.
B) air resistance against the bow.
C) friction of the ground against the archer's feet.
D) grip of the archer's hand on the bow.
E) arrow's push against the bowstring.

5) A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?
A) The player's grip on the glove
B) The force the glove exerts on the ball
C) Friction of the ground against the player's shoes
D) The muscular effort in the player's arms
E) none of the above ________

6) A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction to this force?
A) Air resistance on the ball
B) The weight of the ball
C) The force of the ball against the bat
D) The grip of the player's hand against the bat
E) none of the above ________

7) As a ball falls, the action force is the pull of the earth's mass on the ball. What is the reaction to this force?
A) Air resistance acting against the ball
B) The acceleration of the ball
C) The pull of the ball's mass on the earth
D) Nonexistent in this case
E) none of the above ________

8) A person is attracted towards the center of the earth by a 500-N gravitational force. The force with which the earth is attracted toward the person is __________.
A) very very small.
B) very very large.
C) 500 N.

9) An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, the force of the bug on the car is __________.
A) larger.
B) smaller.
C) the same.
D) Need more information to say

10) An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, the deceleration of the bug is __________.
A) larger.
B) smaller.
C) the same.

11) If a horse pulls on a wagon at rest, the wagon pulls back equally as much on the horse. Will the wagon be set into motion?
A) No, because the forces cancel each other.
B) Yes, because there is a net force acting on the wagon.
C) Yes, because there is a time delay between action and reaction.
D) Yes - The horse's pull on the wagon is larger than the wagon's pull on the horse.

12) A Mack truck and a Volkswagen traveling at the same speed have a head-on collision. The vehicle to undergo the greater change in velocity will be the __________.
A) Volkswagen.
B) Mack truck.
C) Both the same

13) According to Newton's third law, if you push gently on something, it will push __________.
A) gently on you.
B) gently on something else.
C) on something only under the right conditions.
D) on you only if you aren't moving.

14) The earth pulls on the moon, and similarly the moon pulls on the earth. This is evidence that the __________.
A) earth and moon are simply pulling on each other.
B) earth's and moon's pulls comprise an action-reaction pair.
C) both a and b
D) neither a or b

15) Nellie Newton holds an apple in her hand. If action is the earth pulling on the apple, then reaction is __________.
A) her hand pushing up on the apple.
B) her hand providing a normal force on the apple.
C) both A and B
D) neither A nor B

16) Bronco the skydiver falls toward the earth. The attraction of the earth on Bronco pulls him down. The reaction to this force is __________.
A) Bronco finally pushing against the earth's surface.
B) the earth's surface finally pushing against Bronco.
C) Bronco pulling up on the earth.
D) neither A, B, nor C

17) A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by the __________.
A) engine.
B) tires.
C) air.
D) road.

18) A rocket is able to accelerate in the vacuum of space when it fires its engines. The force that propels the rocket is the force __________.
A) of the exhaust gases on the rocket.
B) of the rocket on the exhaust gases.
C) neither A nor B

19) A karate chop delivers a blow of 3000 N to a board that breaks. The force that acts on the hand during this feat __________.
A) is less than 3000 N.
B) is 3000 N.
C) is more than 3000 N.
D) cannot be determined.

20) Your friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair, no wall, no tricks.
A) You agree that it can't be done.
B) You have reservations about this claim.
C) You disagree, for a good punch easily delivers this much force.

21) A woman weighing 500 N sits on the floor. She exerts a force on the floor of __________.
A) 1000 N.
B) 500 N.
C) 250 N.
D) 50 N.
E) 5 N.

22) As a 500-N woman sits on the floor, the floor exerts a force on her of __________.
A) 1000 N.
B) 500 N.
C) 250 N.
D) 50 N.
E) 5 N.

23) Two people pull on a rope in a tug-of-war. Each pulls with 400 N of force. What is the tension in the rope?
A) Zero
B) 400 N
C) 600 N
D) 800 N
E) none of the above

24) Two people, one having twice the mass of the other, play tug-of-war with a 12-meter rope on frictionless ice. After a brief time, they meet. The heavier person slides a distance of __________. A) 3 m.
B) 4 m.
C) 5 m.
D) 6 m.

Write True or False in the space provided.

25) Whenever one object exerts a force on another object, the second object always exerts a force back on the first object. _______

26) A rocketship is pushed forward by gases that are forced out the back of the ship. _______

27) In order to make a cart move forward, a horse must pull harder on the cart than the cart pulls on the horse. _______

28) A bicycle and a parked car have a head-on collision. The force of impact is greater on the bicycle. _______

On a separate sheet of paper, answer the following questions.

29) In a sense, a force is a push or a pull. Newton's third law further defines the meaning of force. Explain.

30) Apply Newton's third law to a falling boulder, identifying the action and reaction forces. If a force is exerted on Earth, why doesn't it move? Explain.

31) Explain how Newton's third law applies to a cannon launching a cannonball. Which has the larger acceleration, the cannonball or the cannon? What if the cannonball were just as massive as the cannon -- how fast would the cannon move compared to the cannonball?

32) Draw the horizontal forces acting on a horse pulling a cart. Draw forces on the cart as well as on the horse. In terms of these forces, explain why the cart moves. Explain why the horse moves. Why don't action-reaction forces cancel each other?

Answer the following questions in the space provided. Show all work.

33) If you push off the ground with a force of 400 N when you jump upward, what force pushes the earth downward?

34) A pair of blocks, one 3 times as massive as the other, are connected by a compressed spring. When the spring is released, the blocks fly apart. Compared to the heavier block, how many times as fast does the lighter block accelerate?

35) Two people have a tug-of-war on low-friction ice. One person has 2 times the mass of the other. Compared to the lighter person, how many times as fast does the heavier person accelerate?

36) A 60-kg person on in-line skates pushes against a wall with a force of 30 N and recoils. What acceleration does that person experence?

37) A boxer punches a sheet of paper in midair, and brings it from rest up to a speed of 40 m/s in 0.05 s. What is the force of impact on the paper if the mass of the paper is 0.01 kg?

38) What engine thrust (in newtons) is required for a rocket of mass 30.0 kg to leave the launching pad?