Problem 1:
The curves on bicycle racetracks are steeply banked, so that the outer edge of each curve is much higher than its inner edge. This banking tips the support force that the track exerts on the bicycle wheel toward the center of each turn. That center-directed or centripetal force on the bicycle is important because it
(A) helps the bicycle accelerate inward to complete each turn without skidding.
(B) it does work on the bicycle during each turn and thus increases the bicycle's energy.
(C) it does negative work on the bicycle during each turn and thus decreases the bicycle's energy.
(D) balances the outward centrifugal force that the bicycle experiences as it completes each turn, so that the bicycle experiences zero net force.
Problem 2:
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 left.
(B) neither team. It was instead provided by chemical potential energy in the rope itself.
(C) both teams.
(D) the team on the right.
Problem 3:
As water in steady state flows straight up in a vertical pipe with a uniform diameter, that water
(A) transforms its gravitational potential energy into pressure potential energy.
(B) transforms its gravitational potential energy into kinetic energy.
(C) transforms its kinetic energy into gravitational potential energy.
(D) transforms its pressure potential energy into gravitational potential energy.
Problem 4:
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 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.
(B) 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.
(C) Its weight.
(D) Its weight along with a steadily decreasing upward force.
Problem 5:
You are out for a bicycle ride on a calm, windless day. You are heading northward on a level road and are experiencing a pressure drag force that pushes you toward the south. This air resistance explains why you have to keep pedaling to maintain your constant speed. If someone were to examine the air that you have left behind you after you have passed through it, they would find that the air's average velocity is
(A) southward.
(B) zero but that it is swirling rapidly in all directions.
(C) zero and that it is calm.
(D) northward.
Problem 6:
A pitcher throws a curveball. While the spinning baseball is in the air between the pitcher and home plate, the forces acting on the ball are its weight, a buoyant force, drag forces, a lift force, and
(A) no other force.
(B) a forward force that is constant from the moment the baseball leaves the pitcher's hand until it crosses home plate..
(C) a forward force that decreases steadily from the moment the baseball leaves the pitcher's hand until it crosses home plate.
(D) a forward force that decreases steadily from the moment the baseball leaves the pitcher's hand until it is half way to home plate, and then is constant until the baseball crosses home plate.
Problem 7:
Air mattresses are hollow, air-filled bags that are used as beds while camping or to accommodate occasional visitors at home. When you lie on a fully inflated air mattress, it supports your weight easily and barely dents at all. But if you stand on it, its surface dents severely and you may actually pop the air mattress. Standing on the air mattress causes the air pressure inside it to rise much more than lying on it does because
(A) you have much more gravitational potential energy when you're standing than when you're lying down and this gravitational potential energy becomes pressure potential energy in the air mattress.
(B) you're supported by the mattress's air pressure and as your contact surface with the mattress decreases, the air pressure needed to support you increases.
(C) you have much more kinetic energy when you're standing than when you're lying down and this kinetic energy becomes pressure potential energy in the air mattress.
(D) you weigh more when you're standing up than you do when you're lying down.
Problem 8:
You are watering the garden with a hose and nozzle. As the water flows through the nozzle, it converts
(A) velocity into acceleration.
(B) pressure potential energy into kinetic energy.
(C) potential energy into momentum.
(D) kinetic energy into momentum.
Problem 9:
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 force of sliding friction that the cloth exerts on the dishes is proportional to the time during which the cloth is moving.
(B) the work done on the dishes by the cloth is proportional to the time during which the cloth pulls on them.
(C) the weight of the dishes on the cloth is proportional to the time during which the cloth is moving.
(D) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them.
Problem 10:
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) The amount of force that you're exerting on the carpet must be equal to amount of force that friction is exerting on it.
(B) If you were to exert twice as much force on the carpet, it would slide across the floor twice as fast.
(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 11:
You are paddling yourself forward in a Kayak, across a calm lake. Each time you pull the paddle backward through the water, from the front of the boat to its rear, the water exerts a force on the paddle that is
(A) in the forward direction, toward the front of boat.
(B) sideways, toward you and the boat.
(C) sideways, away from you and the boat.
(D) in the backward direction, toward the back of the boat.
Problem 12:
A bicycle is remarkably stable while it's moving forward because, when you start to tip over,
(A) the bicycle's base of support becomes much wider so that a torque from the ground returns it to an upright orientation.
(B) your center of gravity naturally descends.
(C) your center of gravity naturally rises.
(D) the bicycle spontaneously steers so that its wheels drive under your center of gravity.
Problem 13:
You are floating along in a hot air balloon. You look up and notice that the bottom of the balloon is open. Apart from a few molecules that diffuse out, hot air remains inside the balloon despite this opening because
(A) hot air has more inertia than cold air and doesn't accelerate easily.
(B) hot air has a lower pressure than cold air, so hot air is drawn into the balloon by the partial vacuum inside it.
(C) the air pressure inside the balloon's opening is the same as the air pressure outside that opening.
(D) the propane burner located below the opening keeps pushing the hot air back into the balloon.
Problem 14:
You are cleaning a wall by spraying water at it from a hose. At the center of the stream of water, right where it hits the wall, the water is coming to a complete stop. If you were to measure the water pressure at that point, you would find that it is
(A) exactly zero.
(B) lower than atmospheric pressure, but more than zero.
(C) higher than atmospheric pressure.
(D) equal to atmospheric pressure.
Problem 15:
If a golf ball were smooth rather than dimpled, it would
(A) not travel as far after being hit by a golf club.
(B) curve toward the left after being hit by the club of a right-handed golfer.
(C) travel much farther after being hit by a golf club.
(D) curve toward the right after being hit by the club of a right-handed golfer.
Problem 16:
When a modern car crashes into a tree and comes to an abrupt stop, the driver's face and chest collide with an air bag rather than with the steering wheel. The driver's chances of serious injury are reduced by hitting the air bag rather than the steering wheel because the driver transfers
(A) the same amount of momentum to the air bag as he would to the steering wheel if there were no air bag, but he does so with a smaller force because of the air bag.
(B) less momentum to the air bag than he would to the steering wheel if there were no air bag.
(C) more momentum to the air bag than he would to the steering wheel if there were no air bag.
(D) the same amount of momentum to the air bag as he would to the steering wheel if there were no air bag, but he does so with a larger force because of the air bag.
Problem 17:
You are riding on a playground swing. As you swing forward, there is a moment when you are directly below the pivot that supports the swing. At that moment, you are
(A) accelerating backward.
(B) accelerating forward.
(C) accelerating upward.
(D) not accelerating at all.
Problem 18:
When a hammer exerts a force on a nail, how does the amount of that force compare to that of the nail on the hammer?
(A) The hammer is pushing harder on the nail than the nail is pushing on the hammer.
(B) They are both exerting the same amount of force on one another.
(C) The nail isn't pushing on the hammer at all, which is why the hammer pushes the nail into the wood.
(D) The nail is pushing harder on the hammer than the hammer is pushing on the nail.
Problem 19:
A block of wood is floating easily on the surface of a lake. As a storm approaches, the density and pressure of the air above the lake decrease. As a result of this decrease in air pressure and density, the block of wood
(A) continues to float just as it did before.
(B) sinks to the bottom of the lake.
(C) moves downward slightly and floats a little deeper in the water.
(D) moves upward slightly and floats a little less deep in the water.
Problem 20:
A helium balloon floats in air because the helium balloon contains
(A) faster-moving helium atoms, which use their kinetic energies to displace the force of gravity.
(B) more particles than the air it displaces and these particles push upward more strongly on the top surface of the balloon.
(C) the same number of particles as the air it displaces, but each helium atom weighs less than the average air molecule.
(D) fewer particles than the air it displaces.
Problem 21:
All current rockets eject stages or booster rockets as they climb from the earth's surface up to orbit. A rocket that didn't eject any stages or booster rockets while climbing from the ground to orbit would
(A) clutter the space around the earth with orbiting debris.
(B) have to have a launch weight that is about 90% rocket fuel.
(C) experience too much drag while in orbit and would be unable to remain in orbit for more than a day or two.
(D) not have anything beneath the rocket on which to push and would be unable to propel itself upward after it left the launch pad area.
Problem 22:
You're filling a jar of honey from the spigot at the bottom of a large, nearly empty barrel at the grocery store. The honey flows extremely slowly, so the store manager has the barrel refilled. Now the honey flows much more rapidly from the spigot because
(A) the viscosity of the honey (its "thickness") increases as the height of honey in the barrel increases.
(B) the viscosity of the honey (its "thickness") decreases as the height of honey in the barrel increases.
(C) the density of the honey decreases as the height of the honey in the barrel increases.
(D) the pressure of the honey at the bottom of the barrel increases as the height of honey in the barrel increases.
Problem 23:
A curve ball's path bends to the right as it flies toward home plate because it's experiencing an aerodynamic force to its right. One reason why the ball is experiencing this aerodynamic lift force is that the ball is spinning and that spin
(A) exerts a torque on the ball that causes its angular momentum to shift toward the left.
(B) exerts a torque on the ball that causes its angular momentum to shift toward the right.
(C) causes the air to flow faster and farther around the left side of the ball than around the right side of the ball.
(D) causes the air to flow faster and farther around the right side of the ball than around the left side of the ball.
Problem 24:
Two glass marbles, one of which weighs twice as much as the other, roll off of a horizontal table. As they leave the table, the lighter marble is traveling twice as fast as the heavier marble. In this situation,
(A) the lighter marble hits the floor about twice as far from the table as the heavier marble.
(B) the lighter marble hits the floor about half as far from the table as the heavier marble.
(C) the two marbles hit the floor at exactly the same distance from the table.
(D) the two marbles hit the floor at slightly different distances from the table.
Problem 25:
You throw a snowball straight up into the air. It rises to a peak height and then descends. At the moment it reaches its peak height, the snowball's velocity is
(A) zero and its acceleration is zero.
(B) downward and its acceleration is zero.
(C) zero and its acceleration is downward.
(D) downward and its acceleration is downward.
Problem 26:
You are on a 10th floor hotel balcony, overlooking the pool. You lower a 100-foot-long straw into the pitcher of lemonade at the bar and try to suck the lemonade up to your mouth. What happens?
(A) You are unable to suck the lemonade up to your mouth.
(B) You succeed in drinking the lemonade almost immediately, but it flows into your mouth at a very slow rate.
(C) You succeed in drinking the lemonade, but it takes a long time for the lemonade to first reach your mouth and then flows into your mouth at a very slow rate.
(D) You succeed in drinking the lemonade at a normal rate, but it takes a long time for the lemonade to first reach your mouth.
Problem 27:
You hold a new glass bottle of root beer upright in one hand and pound its bottle cap downward hard with a rubber mallet. As a consequence of this action,
(A) the sudden expansion of gas inside the bottle causes the top layer of root beer to freeze.
(B) the sudden acceleration causes the liquid in the bottle to float above the gas in the bottle for several seconds.
(C) liquid colliding with the bottom of the bottle knocks the bottom out of the bottle.
(D) the surge in pressure near the top of the bottle causes the bottle cap to vibrate loudly.
Problem 28:
You stop for a cappuccino at Alderman Café and notice that the tiny white bubbles of steamed milk remain on the surface of the coffee. These air-filled bubbles stay where they are, rather than descending into the coffee or rising into the air, because they are
(A) more dense than the coffee but less dense than the air above the coffee.
(B) lighter than the cup of coffee but heavier than the column of air above the coffee.
(C) less dense than the coffee but more dense than the air above the coffee.
(D) more viscous than the coffee but less viscous than the air above the coffee.
Problem 29:
When you ride a bicycle, the ground exerts an upward support force on the wheel. When you turn the bicycle, the ground also exerts a horizontal frictional force on the wheel that causes you to accelerate sideways. Leaning the bicycle toward the inside of a turn keeps you from flipping over because the overall force that the ground exerts on the wheel
(A) produces zero torque on you and the bicycle about your combined center of mass.
(B) points directly upward so that you don't fall downward.
(C) points exactly at right angles to your center of mass and exerts a torque on you that keeps you from falling over.
(D) is exactly zero and causes no acceleration of your center of mass.
Problem 30:
If you're trying to increase the pressure in the water distribution system by modifying the local water tower, you should make the water tower
(A) wider.
(B) taller.
(C) shorter
(D) narrower.