Problem 1:
When you bounce a soccer ball off a stone wall, the ball
(A) retains essentially all of its momentum but transfers a great deal of energy to the wall.
(B) transfers a great deal of momentum and energy to the wall.
(C) retains essentially all of its energy but transfers a great deal of momentum to the wall.
(D) retains essentially all of its energy and momentum.
Problem 2:
You jump while standing on a bathroom scale and the scale briefly reads more than your actual weight. During that moment, the scale is exerting an upward force on you that is
(A) equal to your weight and you are accelerating upward.
(B) greater than your weight and you are accelerating upward.
(C) greater than your weight and your velocity is constant.
(D) equal to your weight and your velocity is constant.
Problem 3:
A boy is bicycling up a hill and appears to need some help. As he passes you, you reach out with your hand and exert an uphill force of 10 N on him. When you do this, the boy exerts
(A) a downhill force of somewhat more than 10 N on you, because, in addition to the reaction force, he must accelerate your hand downhill.
(B) no downhill force on you at all, because the force of his momentum is already enough to keep him moving uphill.
(C) a downhill force of 10 N on you, because forces always come in equal but oppositely directed pairs.
(D) a downhill force of somewhat less than 10 N on you, because his uphill velocity reduces the force he needs to accelerate uphill.
Problem 4:
You are moving into a loft apartment and are now dragging an old carpet across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the carpet is correct?
(A) If you were to exert twice as much force on the carpet, it would slide across the floor twice as fast.
(B) The amount of force that you're exerting on the carpet must be equal to amount of force that friction is exerting on it.
(C) The amount of force that you're exerting on the carpet must be more than the amount of its weight.
(D) The amount of force that you're exerting on the carpet must be more than the amount of force that friction is exerting on it.
Problem 5:
A sack of flour will bounce higher when you drop it onto a mattress than when you drop it onto a cement floor. That's because
(A) the sack of flour has more momentum when it hits the mattress than when it hits the cement floor.
(B) the cement floor has more mass than the mattress.
(C) the cement floor exerts less torque on the sack of flour than the mattress does.
(D) the mattress deforms more as it slows the falling sack of flour and it stores more of the collision energy.
Problem 6:
On a recent trip to the moon, you decide to measure your weight and mass. You find that
(A) your mass is still essentially unchanged but your weight is less than on earth.
(B) your weight is still essentially unchanged but your mass is less than on earth.
(C) your weight and mass have both changed significantly.
(D) neither your weight nor your mass have changed much.
Problem 7:
You're trying to win a stuffed animal at the fair by knocking over a stack of heavy milk bottles with a projectile. You have a choice of four projectiles: a 1-kilogram beanbag, a 2-kilogram beanbag, a 1-kilogram bouncy ball, and a 2-kilogram bouncy ball. Assuming that you can throw each of these projectiles at the same final speed, which one will be most effective at knocking over the milk bottles?
(A) The 2-kilogram beanbag.
(B) The 1-kilogram bouncy ball.
(C) The 1-kilogram beanbag.
(D) The 2-kilogram bouncy ball.
Problem 8:
You are bicycling along a quiet street when a child runs in front of you to retrieve a toy. You slam on the brakes and lock your wheels. The bicycle skids to a stop. What has become of your kinetic energy?
(A) It's now thermal energy in the wheels and ground.
(B) It's still present in you, as it must be because kinetic energy is conserved and can't be created or destroyed.
(C) It's now elastic potential energy in the brakes.
(D) It's now gravitational potential energy in the wheels.
Problem 9:
You are building a decorative mobile, a sculpture consisting of kitchen utensils that hang from one another on strings. One long metal fork is supported by a single string. For the fork to be balanced, that supporting string must be placed
(A) at the fork's center of mass.
(B) midway between the two ends of the fork.
(C) at the fork's center of percussion.
(D) at the fork's center of gravity.
Problem 10:
While wandering in the dark toward the refrigerator, you accidentally walk into a concrete wall and come to a sudden stop without bouncing back. Fortunately, that wall was covered with a soft fabric wall hanging. Coming to a stop on the soft fabric was more pleasant than coming to a stop on the concrete because you transfer
(A) the same momentum to either surface, but you transfer it more slowly to the fabric than to the concrete.
(B) more momentum to the concrete than to the fabric.
(C) more energy to the concrete than to the fabric.
(D) more velocity to the concrete than to the fabric.
Problem 11:
You toss a basketball straight up. Disregarding any effects of due to the air, what force or forces are acting on the basketball while it is above your hands?
(A) Its weight.
(B) Its weight along with a steadily decreasing upward force.
(C) A steadily decreasing upward force from the moment it leaves your hands until it reaches its highest point and then a steadily increasing downward force as the basketball returns toward your hands.
(D) Its weight along with an upward force that steadily decreases until the basketball reaches its highest point. After that point, there is only the constant downward force of gravity.
Problem 12:
You are working in a pizza parlor and have learned how to toss and spin the dough to form large disks. You find that the larger each disk becomes as you spin it, the harder it is to stop the disk from spinning. This effect occurs because spreading the dough into a larger disk increases its
(A) angular velocity.
(B) weight.
(C) rotational mass.
(D) mass.
Problem 13:
You are riding the subway and there is a team of roller skaters standing in aisle. The skaters are not holding on to anything as the subway travels along its route. Suddenly, the roller skaters begin rolling toward the right side of the subway car. You know that the subway car
(A) has accelerated toward the left.
(B) has accelerated toward the right.
(C) is moving at constant velocity toward the left.
(D) is moving at constant velocity toward the right.
Problem 14:
You are riding a stand-up roller coaster and, at this moment, your body is oriented vertically as though you were standing on the ground. However, you feel extraordinarily heavy, as though the earth were pulling you directly downward several times more strongly than usual. At this moment,
(A) your velocity must be downward.
(B) your velocity must be upward.
(C) your acceleration must be upward.
(D) your acceleration must be downward.
Problem 15:
A cheerleader leaps into the air with her arms and legs extended and then pulls herself into a compact ball to complete a somersault. She opens up again and lands on her feet. During the time that she is not touching the ground, one aspect of her motion that is constant is her
(A) angular momentum.
(B) velocity.
(C) angular velocity.
(D) momentum.
Problem 16:
You are arm-wrestling with a friend. You are sitting across from one another with your right arms locked together and each of you is trying to twist the other's arm down to the tabletop. After a few minutes of struggling, you succeed in twisting your friends arm to the tabletop and win. As you won,
(A) you did no work on your friend and the torque that you exerted on your friend was equal in amount to the torque that your friend exerted on you.
(B) you did no work on your friend, but the torque that you exerted on your friend was greater in amount than the torque that your friend exerted on you.
(C) you did work on your friend and the torque that you exerted on your friend was greater in amount than the torque that your friend exerted on you.
(D) you did work on your friend, but the torque that you exerted on your friend was equal in amount to the torque that your friend exerted on you.
Problem 17:
You are water-skiing behind your new yacht and the rope from the yacht is pulling you forward. At this moment, you are traveling in a straight line path at a constant speed. The net force you are experiencing is
(A) in the upward direction.
(B) in the forward direction.
(C) in the backward direction.
(D) zero.
Problem 18:
You are watching children play a game of tug-o-war with a plastic clothesline. The two teams are pulling at opposite ends of the cord and each team is trying to drag the other team into a mud puddle that lies between them. After a few minutes without progress, the team on the right suddenly pulls hard toward the right. The team on the left has anticipated this threat and is able to keep their end of the rope from moving. The right end of the rope stretches toward the right and the rope breaks. Breaking the rope required energy and that energy was provided by
(A) the team on the right.
(B) neither team. It was instead provided by chemical potential energy in the rope itself.
(C) the team on the left.
(D) both teams.
Problem 19:
You're having trouble loosening a rusty nut with a small wrench, so you borrow a large wrench from your neighbor. Exerting only a modest force on the handle of this new wrench easily unscrews the nut. The large wrench helps because it
(A) allows you to exert your force far from the center of rotation, so that you produce a large torque on the nut.
(B) has a large acceleration and a large mass, so the force it produces is large, according to the equation F=ma.
(C) has a large moment of inertia so that it develops a great deal of angular momentum when you exert a force on it.
(D) has a large mass so that its inertia allows you to overcome the nut's velocity and accelerate it around in a circle.
Problem 20:
An amazing skater is coasting past you on frictionless ice. You reach out and drop a bouquet of roses straight down into her open arms. As a result receiving your gift, the skater
(A) retains exactly the same forward velocity because velocity is conserved.
(B) slows down because her initial momentum is now distributed over more mass.
(C) retains exactly the same forward velocity because only her overall weight has increased.
(D) speeds up because her forward momentum has increased.
Problem 21:
Two bowling balls, one of which weighs twice as much as the other, roll off of a horizontal table together at the same initial velocity. In this situation,
(A) both balls hit the floor at approximately the same time, but the heavier ball lands considerably farther from the table than the lighter ball does.
(B) the heavier ball hits the floor first and it lands considerably farther from the table than the lighter ball does.
(C) both balls hit the floor at approximately the same time and at the same distance from the table.
(D) the heavier ball hits the floor first and it lands considerably closer to the table than the lighter ball does.
Problem 22:
When you pull a tablecloth out from under a set of dishes, it's important to pull the cloth as fast as possible because
(A) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them.
(B) the force of sliding friction that the cloth exerts on the dishes is proportional to the time during which the cloth is moving.
(C) the weight of the dishes on the cloth is proportional to the time during which the cloth is moving.
(D) the work done on the dishes by the cloth is proportional to the time during which the cloth pulls on them.
Problem 23:
You are at the gym, exercising on a step machine. You have one foot on each of the machine's pedals and you move those pedals up and down as you step. The pedals always push upward on your feet, but they push harder while moving downward than while moving upward. When during this exercise are you transferring energy to the step machine?
(A) As the pedals move downward.
(B) As the pedals move upward.
(C) As the pedals move either upward or down.
(D) When the pedals are accelerating.
Problem 24:
You are watching a volleyball game and the server has just hit the ball over the net toward the opponents side. Once the ball has left the server's hand and is heading forward toward the opponents' side, it experiences
(A) a forward horizontal force until it reaches its highest point over the net and then a backward horizontal force for the remainder of its trip.
(B) a forward horizontal force that remains constant all the way to the opponent's side.
(C) no horizontal force in the forward direction.
(D) a forward horizontal force that diminishes gradually as the ball approaches the opponents' side.
Problem 25:
You are practicing the trapeze at circus camp and you lose your grip on the bar. You fall into the net far below and bounce comfortably up and down. After a few seconds, you settle down at equilibrium in the net. When during your fall and first rebound upward were you accelerating downward?
(A) Whenever you were above your equilibrium in the net.
(B) Only when you were not touching the net during both your fall and your rebound.
(C) Only until you touched the net during your initial fall.
(D) Only when you had not yet reached the lowest point during your first bounce off the net.
Problem 26:
You are sitting on a merry-go-round at the playground and it is spinning rapidly. As the merry-go-round spins, the net force on you points
(A) away from the merry-go-round's center and you experience a feeling of acceleration toward its center.
(B) away from the merry-go-round's center and you experience a feeling of acceleration away from its center.
(C) toward the merry-go-round's center and you experience a feeling of acceleration toward its center.
(D) toward the merry-go-round's center and you experience a feeling of acceleration away from its center.
Problem 27:
You're pushing your little cousin in a rocking chair. To make the chair rock farther and farther, you should only push it forward when it's
(A) on your side of its equilibrium position.
(B) on the far side of its equilibrium position.
(C) rocking away from you.
(D) rocking toward you.
Problem 28:
You toss your backpack directly upward and watch it rise to its peak height. At the moment that it reaches that peak height, its velocity is
(A) downward and its acceleration is zero.
(B) downward and its acceleration is downward.
(C) zero and its acceleration is downward.
(D) zero and its acceleration is zero.
Problem 29:
You're playing soccer and the other team's goalie has kicked the ball directly toward you. You kick the ball back and score a goal. If the goalie had rolled the ball slowly toward you instead, how would that have affected the ball's speed after you kicked it with the same motion of your foot?
(A) The slower-moving ball would have traveled away from you faster after you kicked it because of its centripetal force.
(B) The slower-moving ball would have traveled away from you faster after you kicked it because its momentum wouldn't have to change as much to go back fast.
(C) The slower-moving ball would also have traveled away from you slower after you kicked it.
(D) The slower-moving ball would have traveled away from you faster after you kicked it because of the force of its momentum.
Problem 30:
You're a counselor at summer camp and your group of kids has talked you into jumping off the roof of the boathouse into the lake beneath it. You're secretly worried about hurting yourself when you hit the water, so you decide to make sure that your speed is a small as possible when you reach the water's surface. Of the following ways to leave the roof, which one will give you the smallest speed when you reach the water?
(A) Jumping upward as you walk off the roof.
(B) Running as quickly as possible off the roof.
(C) Hooking your toes around the edge of the roof and pulling yourself downward as you step off the roof.
(D) Walking as slowly as possible off the roof.