Physics 1050 - How Things Work - Fall 2009 Midterm Examination 1 Solutions

At high altitude, a commercial jetliner must compress the outside air before circulating it in the pressurized cabin. But the compressed air must first be sent through an air conditioner because compressing air

(A) decreases its humidity. [3.1% picked]

(B) turns it into a liquid and the air conditioner's evaporator allows it to return to a gas. [18.9% picked]

(D) increases its humidity. [7.0% picked]

The reason that a watch with a balance ring and a spring keeps good time is that

(A) it contains a quartz crystal. [6.2% picked]

(B) the ring oscillates back and forth with a constant frequency determined principally by the ring's weight and the spring's mass. [7.0% picked]

(C) the ring oscillates back and forth with a constant frequency determined principally by the ring's rotational mass and the spring's stiffness. [62.6% picked]

(D) the ring oscillates back and forth with constant frequency determined principally by the force of gravity and the length of the pendulum rod. [17.2% picked]

Answer: (C) the ring oscillates back and forth with a constant frequency determined principally by the ring's rotational mass and the spring's stiffness. [62.6% picked]

After clearing the bar in the high jump, you land softly on a giant mattress. Landing on the mattress is much more comfortable than landing on a sand heap of equal size because

(A) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more mass to stop you. [0.9% picked]

(B) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you. [92.5% picked]

(C) you transfer less momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop. [2.2% picked]

(D) you transfer more momentum to the mattress in coming to a stop than you would have transferred to the sand heap in coming to a stop. [4.0% picked]

Answer: (B) you transfer the same momentum to the mattress in coming to a stop as you would have transferred to the sand heap in coming to a stop, but the mattress takes more time to stop you. [92.5% picked]

Goose down is the soft, fluffy feathers near a goose's skin. The reason that a goose down jacket keeps you so warm in the winter is that

(A) the fine structure of the goose down traps air and prevents it from undergoing convection. [80.6% picked]

(B) goose down's low average density reduces its buoyant force. [0.4% picked]

(C) goose down's white coloring assists the radiative transfer of heat from the outer surface of the coat to your skin. [1.3% picked]

(D) the fibrous material in goose down is a poorer conductor of heat than the air it displaces. [15.4% picked]

Answer: (A) the fine structure of the goose down traps air and prevents it from undergoing convection. [80.6% picked]

You and friend are paddling a canoe across a lake. You both reach forward with your paddles raised above the water, lower the paddles into the water, and then pull the paddles backward toward you. The canoe accelerates forward as you pull backward on your paddles, because as you pull backward,

(A) the water level behind the canoe rises and the canoe accelerates down the inclined plane that you are producing. [3.5% picked]

(B) the water pushes forward on your paddles. [89.9% picked]

(D) the weight of the canoe is reduced. [0.4% picked]

You are juggling grapefruits in your hands and are about to toss one far above your head. After it leaves your hand, the grapefruit will experience

(A) both an upward force and the downward force of its weight as it rises. The upward force will gradually diminish to zero at the grapefruit's peak height, after which the grapefruit will experience only the downward force of its weight. [4.0% picked]

(B) an upward force as it rises. This upward force will gradually diminish to zero at the grapefruit's peak height, after which the grapefruit will experience only the downward force of its weight. [3.1% picked]

(C) the upward force of its weight as it rises. Once the grapefruit reaches its peak height, it will begin to experience the downward force of its weight. [1.3% picked]

(D) only the downward force of its weight, both before and after it reaches its peak height. [91.2% picked]

Answer: (D) only the downward force of its weight, both before and after it reaches its peak height. [91.2% picked]

You toss a bottle straight up. Disregarding any effects due to the air, what force or forces are acting on the bottle while it is above your hands?

(A) The bottle's weight. [93.0% picked]

(B) The bottle's weight along with an upward force that steadily decreases until the bottle reaches its highest point. After that point, there is only the constant downward force of gravity. [4.4% picked]

(C) A steadily decreasing upward force from the moment The bottle leaves your hands until it reaches its highest point and then a steadily increasing downward force as the bottle returns toward your hands. [2.2% picked]

(D) The bottle's weight along with a steadily decreasing upward force. [0.4% picked]

A toy top is spinning steadily on a table, with only its sharp point touching the table's surface. What is keeping it spinning?

(A) A torque about its center of mass, produced by the support force that the table exerts on the top's point. [32.2% picked]

(B) No torque at all, just its own angular momentum. [49.8% picked]

(D) A torque about the top's point, produced by the top's weight. [4.4% picked]

You are filling a large lightweight dry cleaning bag with helium. At first, the plastic bag doesn't float. But as you keep adding helium to the bag, it eventually begins floating because

(A) the helium-filled bag's weight decreases as you put more lightweight helium particles inside it and eventually it becomes weightless. [10.1% picked]

(B) the upward buoyant force on a bag full of helium is larger than the buoyant force on an identical bag full of air. [32.2% picked]

(C) the average pressure of the helium-filled bag increases as it fills and its pressure eventually becomes greater than that of the air it displaces. [8.4% picked]

(D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces. [46.7% picked]

Answer: (D) the average density of the helium-filled bag decreases as it fills and its density eventually becomes less than that of the air it displaces. [46.7% picked]

Water hammer occurs when you suddenly stop the flow of water in a pipe. It happens because flowing water has

(A) no friction. [2.2% picked]

(B) momentum and can only be stopped by a force. [91.2% picked]

(D) acceleration and can only be stopped by a velocity. [0.9% picked]

You place three nonflammable objects in a fire. They are identical in shape and size, but one object is black, the second is white, and the third is shiny silver. After a few minutes, all three objects are at the same temperature: 1800 °C. They remain solid and are now glowing with thermal radiation. Which one is glowing most brightly?

(A) The third object (silver). [9.3% picked]

(B) The second object (white). [5.7% picked]

(D) The first object (black). [78.9% picked]

You are in a spaceship far from earth and you fire a cannonball into frictionless, empty space. While the cannonball travels forward through space at enormous speed, the net force on that cannonball is

(A) the force of the cannonball's momentum. [3.5% picked]

(B) the force of the cannonball's velocity. [0.4% picked]

(D) the force of the cannonball's mass. [5.3% picked]

One warm spring day you and some friends go to the beach at a nearby lake. You are tossing a soft, almost fully inflated beach ball around when someone accidentally knocks it into the lake. Although it is a very hot day, the water is very cold and nobody wants to retrieve the ball. You notice that the ball seems to have deflated somewhat after sitting in the water for a while. The contact with the cool water has caused the temperature of the air inside the ball to drop, resulting in a significant

(A) increase in the density of the air inside the ball. [11.5% picked]

(B) increase in the pressure inside the ball. [1.3% picked]

(D) decrease in the density of the air inside the ball. [8.8% picked]

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 work done on the dishes by the cloth is proportional to the time during which the cloth pulls on them. [13.7% picked]

(B) the weight of the dishes on the cloth is proportional to the time during which the cloth is moving. [0.0% picked]

(C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them. [63.4% picked]

(D) the force of sliding friction that the cloth exerts on the dishes is proportional to the time during which the cloth is moving. [20.7% picked]

Answer: (C) the momentum transferred to the dishes is proportional to the time during which the cloth pulls on them. [63.4% picked]

If you try to cook vegetables with 100 °C air, it takes a very long time. But if you cook those same vegetables with 100 °C steam, they cook very quickly. This is because the steam

(A) condenses on the colder vegetables and absorbs a large amount of heat from the vegetables. [4.0% picked]

(B) causes moisture inside the vegetables to boil and transfer heat to the vegetables. [15.0% picked]

(D) condenses on the colder vegetables and releases a large amount of heat to the vegetables. [76.7% picked]

Answer: (D) condenses on the colder vegetables and releases a large amount of heat to the vegetables. [76.7% picked]

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) taller. [78.0% picked]

(B) wider. [8.4% picked]

(D) shorter [4.0% picked]

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) both teams. [26.4% picked]

(B) the team on the left. [1.8% picked]

(D) neither team. It was instead provided by chemical potential energy in the rope itself. [4.0% picked]

Independent, gaseous water molecules can leave the surface of hot water at 212 °F (100 °C)

(A) and the surface of room temperature water at 68 °F (20 °C) but not the surface of ice at 0 °F (-18 °C). [8.8% picked]

(B) and the surface of ice at 0 °F (-18 °C) but not the surface of room temperature water at 68 °F (20 °C). [14.1% picked]

(D) but not the surfaces of room temperature water at 68 °F (20 °C) or ice at 0 °F (-18 °C). [14.1% picked]

Answer: (C) and the surfaces of room temperature water at 68 °F (20 °C) and ice at 0 °F (-18 °C). [52.0% picked]

(A) it usually begins to boil, but it requires additional energy to convert from a liquid to a gas without changing temperature. [51.5% picked]

(B) water molecules first begin to leave the water's surface as a gas. [27.3% picked]

(C) it usually begins to boil, but its requires additional energy to convert from a liquid to a gas because it must change temperature to undergo the change of phase. [14.1% picked]

(D) it immediately turns to steam without the further introduction of energy. [1.8% picked]

Answer: (A) it usually begins to boil, but it requires additional energy to convert from a liquid to a gas without changing temperature. [51.5% picked]

Houses often emit creaking sounds as they cool off at night. Since sound carries energy, the house must obtain that energy from somewhere. While this energy begins as thermal energy, the sound doesn't appear until the outside temperature drops well below the temperature of the house because

(A) building materials become too soft during the day to vibrate with enough efficiency to convert thermal energy into sound energy. [7.0% picked]

(B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air. [82.4% picked]

(D) the house's thermal energy increases most rapidly after dark. [0.9% picked]

Answer: (B) the house's thermal energy can only become work and sound as heat flows from the hotter house to the colder outside air. [82.4% picked]

You drop an extremely bouncy rubber ball on a cement floor and it rebounds upward almost to its original height. Compare the ball's energy and momentum just before it bounced on the floor with its energy and momentum just after bounced off the floor.

(A) The ball's energy and momentum changed only a little. [22.5% picked]

(B) The ball's energy and momentum changed significantly. [3.1% picked]

(D) The ball's energy changed significantly, but its momentum changed only a little. [5.3% picked]

Answer: (C) The ball's energy changed only a little, but its momentum changed significantly. [67.8% picked]

(A) the increased pressure on the ice's bottom surface causes the ice to melt and it refreezes on top. [0.4% picked]

(B) ice is less dense than water at 0 °C, so the ice experiences an upward buoyant force that is greater than its downward weight. [98.2% picked]

(D) water contains some salt and the salt makes it much heavier than ice. [0.0% picked]

Answer: (B) ice is less dense than water at 0 °C, so the ice experiences an upward buoyant force that is greater than its downward weight. [98.2% picked]

(A) the air is almost saturated with water vapor, so there is almost no evaporation. [76.7% picked]

(B) the water vapor in the air is moving too fast to condense on your skin as perspiration. [6.6% picked]

(D) the air density is extremely low and its pressure is too high to permit water to evaporate. [7.0% picked]

Answer: (A) the air is almost saturated with water vapor, so there is almost no evaporation. [76.7% picked]

You are in the kitchen with three mixing bowls in front of you. One bowl is metal, the second is glass, and the third is plastic. All three are at exactly the same temperature. If you touch the three bowls together,

(A) no heat will flow between the bowls. [85.9% picked]

(B) heat will flow from the plastic bowl to the glass bowl, and from the glass bowl to the metal bowl. [1.8% picked]

(D) heat will flow from the metal bowl to the glass bowl, and from the glass bowl to the plastic bowl. [8.4% picked]

If you blow properly across the top of a soft drink bottle, it will emit a tone similar to that of a flute or a pipe organ. As the tone is sounding, air is oscillating back and forth through the mouth of the bottle. Inside the bottle, the air's

(A) acceleration remains constant. [3.5% picked]

(B) pressure is alternately increasing and decreasing. [49.8% picked]

(D) velocity remains constant. [7.0% picked]

As air flows around a fast-moving ball, that air has difficulty maintaining laminar flow from the ball's sides to the ball's back. During the air's passage from sides to back, the pressure along each streamline

(A) decreases and the airflow slows down. [7.5% picked]

(B) increases and the airflow speeds up. [10.1% picked]

(D) increases and the airflow slows down. [41.0% picked]

A space-walking astronaut in orbit around the earth has a weight of 600 newtons. This means that the earth exerts a downward force of 600 newtons on the astronaut. How much upward force does she exert on the earth?

(A) 600 newtons. [74.4% picked]

(B) somewhat more than 600 newtons because she is accelerating downward. [0.0% picked]

(D) somewhat less than 600 newtons because she is accelerating downward. [7.5% picked]

Your glass of water has one cube of ice floating at the water's surface. Part of the cube is above the water. When you pour a layer of chilled olive oil onto the water's surface, the ice cube

(A) moves downward slightly. [37.0% picked]

(B) moves upward slightly. [47.6% picked]

(D) floats at the same height as before. [9.3% picked]

You are pushing a file cabinet across the floor in a straight line at a steady speed. Which of the following statements about the forces acting on the file cabinet is correct?

(A) The amount of the force that you're exerting on the file cabinet must be more than the amount of its weight. [0.9% picked]

(B) The amount of the force that you're exerting on the file cabinet must be equal to the amount of the force that friction is exerting on it. [78.9% picked]

(C) The amount of the force that you're exerting on the file cabinet must be more than the amount of the force that friction is exerting on it. [17.6% picked]

(D) If you were to exert twice as much force on the file cabinet, it would slide across the floor at twice its original speed. [2.6% picked]

Answer: (B) The amount of the force that you're exerting on the file cabinet must be equal to the amount of the force that friction is exerting on it. [78.9% picked]

(A) their densities must be increased considerably before they will ignite. [2.2% picked]

(B) they must be compressed into liquid before they can burn. [1.3% picked]

(D) something must provide the activation energy needed to initiate the chemical reaction. [93.8% picked]

Answer: (D) something must provide the activation energy needed to initiate the chemical reaction. [93.8% picked]

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 the amount of force that friction is exerting on it. [80.6% picked]

(B) 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. [16.3% picked]

(D) If you were to exert twice as much force on the carpet, it would slide across the floor twice as fast. [2.2% picked]

Answer: (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. [80.6% picked]

Wrapping a hot potato in aluminum foil helps keep the potato warm because the shiny aluminum foil is

(A) actually transparent to infrared radiation and allows radiant heat from the room to enter the potato and keep it warm. [7.5% picked]

(B) a very poor emitter of thermal radiation. [65.2% picked]

(C) a poor conductor of heat, so the surface temperature of the foil is much less than the surface temperature of the potato. [25.6% picked]

(D) so thin that it doesn't have enough mass to cool the potato significantly. [0.0% picked]

If you strike a stiff, spring-like surface with a mallet and listen to the sound it emits, you'll notice that this sound is more complicated than that emitted by a string or a thin bar. That's because surfaces

(A) are not harmonic oscillators. [25.6% picked]

(B) are harmonic oscillators. [11.0% picked]

(D) have overtones that are not integer multiples of their fundamental frequencies. [29.5% picked]

Answer: (D) have overtones that are not integer multiples of their fundamental frequencies. [29.5% picked]

You are cleaning the siding on your house by spraying water at it from a hose and nozzle. At the center of the stream of water, right where it hits the siding, the water is coming to a complete stop. The pressure in the water at the center of the stream as it touches the siding is

(A) exactly zero. [3.5% picked]

(B) higher than atmospheric pressure. [73.6% picked]

(D) equal to atmospheric pressure. [11.0% picked]

If you blow carefully across the top of a drinking straw, it will emit a tone. If you now close off the bottom of the straw with your finger, the tone that it emits will

(A) go down by an octave (its frequency will decrease by a factor of 2). [60.4% picked]

(B) stay the same. [2.2% picked]

(D) go up by an octave (its frequency will increase by a factor of 2). [30.4% picked]

Answer: (A) go down by an octave (its frequency will decrease by a factor of 2). [60.4% picked]

When you stand in front of an open refrigerator, trying to decide which flavor of Ben and Jerry's to eat, you feel cold even though no chilled air actually touches your skin. The reason you feel cold is that

(A) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return. [89.0% picked]

(B) you can sense the presence of nearby cold air, even though it is not exchanging cold with your skin. [0.9% picked]

(D) the cold refrigerator is radiating cold toward you and is lowering the temperature of your skin directly. [7.9% picked]

Answer: (A) you are radiating heat toward the refrigerator but receiving relatively little radiated heat in return. [89.0% picked]

Moments before it's ignited by the sparkplug, the mixture of fuel and air inside an automobile engine cylinder is compressed to very high density. During the compression process, the mixture's

(A) temperature rises dramatically but its pressure drops. [4.0% picked]

(B) temperature drops dramatically but its pressure rises. [3.1% picked]

(D) temperature stays the same but its pressure rises. [4.4% picked]

Answer: (C) temperature rises dramatically and so does its pressure. [87.7% picked]

(A) water's larger pressure favors turbulent flow. [0.0% picked]

(B) water's larger viscosity favors turbulent flow. [3.5% picked]

(D) honey's larger viscosity favors laminar flow. [88.5% picked]

(A) lowers the string's frequency or pitch by softening the string's restoring force. [0.0% picked]

(B) raises the string's frequency or pitch by stiffening the string's restoring force. [95.2% picked]

(D) lowers the string's frequency or pitch by stiffening the string's restoring force. [4.0% picked]

Answer: (B) raises the string's frequency or pitch by stiffening the string's restoring force. [95.2% picked]

You are taking a nap on the couch. A foam cushion is supporting your head so that your head is in equilibrium. The cushion is dented downward 2 inches from its equilibrium shape. You lift your head to look at the clock, then let your head drop freely against the cushion. Your head dents the cushion downward 4 inches before rebounding back upward. The point at which your head reaches maximum speed during this drop and bounce is when it is

(A) just touching the cushion on its trip downward. [41.9% picked]

(B) denting the cushion downward 4 inches. [14.5% picked]

(D) just touching the cushion on its trip upward. [7.9% picked]

If you blow across the top of a half full bottle of soda you can produce a clear tone. If you take a drink of soda to reduce the amount of liquid in the bottle and try this again the pitch (frequency) of the sound produced will

(A) increase. [31.3% picked]

(B) decrease. [65.6% picked]

(D) stay the same, regardless of how hard you blow. [2.2% picked]

You are standing behind a swing, pushing your little cousin on that swing. To make your cousin swing farther and faster, you should only push your cousin forward when your cousin is

(A) on your side of the equilibrium position. [3.5% picked]

(B) moving forward. [93.4% picked]

(D) moving backward. [1.8% picked]

During the power stroke in one cylinder of a car's engine, the burned fuel and air push the piston out of the cylinder. In accordance with Newton's third law, the piston pushes back on the burned gas. Overall, the

(A) burned gas does work on the piston and the gas experiences a rise in temperature. [25.1% picked]

(B) piston does work on the burned gas and the gas experiences a rise in temperature. [15.4% picked]

(D) piston does work on the burned gas and the gas experiences a drop in temperature. [2.2% picked]

Answer: (C) burned gas does work on the piston and the gas experiences a drop in temperature. [53.7% picked]

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) Only when you had not yet reached the lowest point during your first bounce off the net. [7.0% picked]

(B) Only until you touched the net during your initial fall. [3.5% picked]

(D) Only when you were not touching the net during both your fall and your rebound. [18.5% picked]

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) points directly upward so that you don't fall downward. [7.5% picked]

(B) points exactly at right angles to your center of mass and exerts a torque on you that keeps you from falling over. [41.9% picked]

(D) produces zero torque on you and the bicycle about your combined center of mass. [44.5% picked]

Answer: (D) produces zero torque on you and the bicycle about your combined center of mass. [44.5% picked]

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) northward. [49.8% picked]

(B) zero and that it is calm. [4.0% picked]

(D) southward. [6.6% picked]

If you place a window air conditioning unit on a table in the middle of your sealed room, plug it in, and turn it on, you will find that the average temperature of your room will

(A) rise slightly for about one minute, then fall dramatically as the unit begins to function. [2.6% picked]

(B) rise. [74.9% picked]

(D) fall. [2.2% picked]

A guitar string that normally vibrates with a fundamental frequency of 110 Hz is also capable of vibrating at 330 Hz. When that higher frequency vibration occurs, the string is vibrating

(A) with only one-third of its normal tension. [7.5% picked]

(B) as 3 strings that are each one-third as long as the overall string. [58.1% picked]

(D) with only one-third of its normal mass. [11.0% picked]

Answer: (B) as 3 strings that are each one-third as long as the overall string. [58.1% picked]

Some satellites orbit the earth at such large distances that they are never in the earth's shadow. These satellites are constantly exposed to full sunlight. With no air around them to take away heat, why don't these satellites continue to grow hotter forever?

(A) They use air conditioners to eliminate the excess thermal energy as rapidly as it arrives. [4.4% picked]

(B) They have solar panels that convert the sun's thermal radiation completely into electricity and avoid any need to eliminate heat. [26.4% picked]

(C) Because they are isolated from the sun by empty space, the sun's heat can't reach them and they don't experience any changes in temperature. [11.5% picked]

(D) Their temperatures rise until they are able to radiate heat away into space as fast as it arrives from the sun. [53.3% picked]

Answer: (D) Their temperatures rise until they are able to radiate heat away into space as fast as it arrives from the sun. [53.3% picked]

A child is playing on a swing. As long as he doesn't swing too high the time it takes him to complete one full oscillation will be independent of

(A) both the length of the ropes supporting the swing and the amplitude of the child's motion. [9.7% picked]

(B) the weight of the child, but not of the amplitude of the child's motion. [8.4% picked]

(D) the amplitude of the child's motion, but not of the weight of the child. [24.7% picked]

Answer: (C) both the amplitude of the child's motion and of the weight of the child. [55.5% picked]

You have installed a fountain in your backyard fish pond. Water flows through a pipe to a nozzle, then rises 10 feet upward in the open air. As water flows along a streamline in this system, its energy changes forms several times. As the water passes through the nozzle its energy transforms from

(A) kinetic energy to pressure potential energy and as the water rises to its peak height its energy transforms from pressure potential energy to gravitational potential energy. [9.3% picked]

(B) pressure potential energy to gravitational energy and as the water rises to its peak height its energy transforms from gravitational energy to pressure potential energy. [9.3% picked]

(C) kinetic energy to pressure potential energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy. [3.1% picked]

(D) pressure potential energy to kinetic energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy. [78.4% picked]

Answer: (D) pressure potential energy to kinetic energy and as the water rises to its peak height its energy transforms from kinetic energy to gravitational potential energy. [78.4% picked]

If you increase the length of the pendulum in your grandfather clock, which previously kept excellent time, you will discover that the clock is

(A) running slow (the clock's minute hand takes more than 60 minutes to complete a full rotation). [74.4% picked]

(B) still keeping excellent time because the period of oscillation of a pendulum depends only on the weight of the pendulum and the strength of gravity. [9.3% picked]

(D) still keeping excellent time because the period of oscillation of a pendulum depends only on the mass of the pendulum and the strength of gravity. [11.9% picked]

Answer: (A) running slow (the clock's minute hand takes more than 60 minutes to complete a full rotation). [74.4% picked]

Two cans of soup, 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 cans hit the floor at approximately the same time, but the heavier can lands considerably farther from the table than the lighter can does. [22.5% picked]

(B) the heavier can hits the floor first and it lands considerably farther from the table than the lighter can does. [1.3% picked]

(D) the heavier can hits the floor first and it lands considerably closer to the table than the lighter can does. [2.2% picked]

Answer: (C) both cans hit the floor at approximately the same time and at the same distance from the table. [73.1% picked]

(A) curve toward the left after being hit by the club of a right-handed golfer. [0.9% picked]

(B) not travel as far after being hit by a golf club. [93.4% picked]

(D) travel much too far after being hit by a golf club. [2.2% picked]

When you jump while standing on a bathroom scale, it briefly reads more than your actual weight. During that moment, it's exerting an upward force on you that is

(A) equal to your weight and your velocity is constant. [0.9% picked]

(B) greater than your weight and your velocity is constant. [4.4% picked]

(D) greater than your weight and you are accelerating upward. [89.4% picked]

Answer: (D) greater than your weight and you are accelerating upward. [89.4% picked]

(A) almost that of empty space-a few degrees above absolute zero. [17.2% picked]

(B) essentially the same as it is now. [0.4% picked]

(D) significantly hotter than it is now. [43.2% picked]

Heat flows spontaneously from a warm hot tub to a cool swimming pool because this heat transfer causes

(A) the entropy of the warmer object (the hot tub) to increase. [2.2% picked]

(B) the total entropy of the two objects to decrease. [7.5% picked]

(D) the entropy of the cooler object (the pool) to decrease. [5.3% picked]

You are mountain biking through the woods and come to a deep gully. The bottom of the gully is a smooth bowl shape without any obstacles. Neglecting friction and air resistance, you are able to coast down one side and back up the other without pedaling. When you are at the bottom of the gully, you feel

(A) heavier than normal since you are accelerating downward. [10.1% picked]

(B) lighter than normal since you are accelerating upward. [4.8% picked]

(D) heavier than normal since you are accelerating upward. [62.6% picked]

Answer: (D) heavier than normal since you are accelerating upward. [62.6% picked]

A friend suggests that you invest in a new invention that supposedly absorbs heat from the room and converts it into electricity. According to a brochure, the device sits in the middle of the room, gradually cooling the room air while providing a steady and endless supply of electric power. You wisely choose not to invest in the device because in order to work as described, it would have to do something impossible-it would have to

(A) turn work into heat, or more precisely, into thermal energy. [5.3% picked]

(B) violate the conservation of energy. [19.8% picked]

(D) turn stored energy into power. [2.6% picked]

The flow of air around a ball can be perfectly laminar only when the ball is traveling extremely slowly through the air. During such laminar flow, the ball experiences

(A) neither viscous drag nor pressure drag. [15.4% picked]

(B) viscous drag but not pressure drag. [45.4% picked]

(D) both viscous drag and pressure drag. [7.9% picked]