Q&A Hero

Q: After an apple pie is taken from an oven, the pie filling is hotter than the crust due to A) water in the filling that better retains thermal energy. B) uneven temperatures. C) high conductivity of apples.

Q: A substance that heats up relatively quickly has a A) high specific heat capacity. B) low specific heat capacity. C) high or low specific heat capacity.

Q: To say that water has a high specific heat capacity is to say that water A) requires a lot of energy for an increase in temperature. B) releases a lot of energy in cooling. C) absorbs a lot of energy for an increase in temperature. D) all of the above

Q: Entropy is most closely related to the A) first law of thermodynamics. B) second law of thermodynamics. C) both of these D) none of the above

Q: As your room gets messier day by day, entropy is A) increasing. B) decreasing. C) hanging steady. D) none of the above

Q: As a system becomes more disordered, entropy A) increases. B) decreases. C) remains the same.

Q: More disorder means A) greater entropy. B) no particular change in entropy. C) less entropy.

Q: As entropy in a system increases, energy within the system A) becomes more ordered. B) becomes less ordered. C) reaches equilibrium. D) moves toward destruction.

Q: The direction of natural processes is from states of A) higher order to lower order. B) lower order to higher order. C) disorganization to organization. D) imbalance to equilibrium.

Q: Because a refrigerator operates by a motor, leaving the refrigerator door open for hours in a closed room A) increases room temperature. B) decreases room temperature. C) doesn't affect room temperature.

Q: Leaving a hot oven door open in a closed room on a cool day A) decreases room temperature. B) increases room temperature. C) doesn't affect room temperature.

Q: When you rapidly stir some raw eggs with an egg beater, their temperature A) increases. B) decreases. C) remains unchanged.

Q: When work is done on a system while additional heat is subtracted, the temperature of the system A) increases. B) decreases. C) remains unchanged. D) need more information

Q: When work is done by a system and heat is subtracted, the temperature of the system A) increases. B) decreases. C) remains unchanged.

Q: When work is done by a system and no heat is added, the temperature of the system A) increases. B) decreases. C) remains unchanged.

Q: When you place a sealed can of air on a hot stove, air in the can undergoes an increase in A) thermal energy. B) temperature. C) pressure. D) all of the above E) none of the above

Q: When Paul compresses air with a tire pump, the temperature of the compressed air A) drops. B) remains unchanged. C) increases as work is done on it. D) none of the above

Q: Which law of thermodynamics addresses the direction of heat flow? A) First law B) Second law C) Third law D) all of the above

Q: Which law of thermodynamics states that no system can reach absolute zero? A) First law B) Second law C) Third law D) all of the above

Q: Which law of thermodynamics is a restatement of the conservation of energy as it applies to thermal systems? A) First law B) Second law C) Third law D) all of the above

Q: The temperature of water rises when 2.00 calories are added. It will rise the same when A) 4.19 J are added. B) 8.38 J are added. C) 83.4 J are added.

Q: The final temperature of 1 liter of 40C water poured into 1 liter of 20C water is A) less than 30C. B) at or about 30C. C) more than 30C.

Q: If the same quantity of heat is added to both a 2-liter and a 4-liter container of water, the temperature change in the 4-liter container will be A) less. B) the same. C) greater.

Q: If the same quantity of heat is added to both a 1-liter and a 2-liter container of water, the temperature change in the 1-liter container will be A) less. B) the same. C) greater.

Q: Increasing the temperature of 1 gram of ice-cold water to the temperature of boiling water requires A) 80 calories. B) 100 calories. C) 540 calories. D) none of the above

Q: Why is an umbrella in danger of being turned inside out on a windy day?

Q: Which is greater, the buoyant force that acts on an elephant, or on a helium-filled party balloon? Explain why the balloon rises in air and the elephant doesn't.

Q: Why will a helium-filled balloon rise in air while an air-filled balloon sinks?

Q: We know that any body more dense than water will sink in water. Why?

Q: Explain in terms of buoyant force how a fish is able to rise and sink in water. Contrast this to the way a submarine rises and sinks.

Q: Explain why ships of any weight are balanced on the Falkirk Wheel.

Q: What is the approximate density of a fish, compared with the density of water? Defend your answer.

Q: Wood from the Lignum vitae tree in South America is denser than water. Could a boat be made with this wood? A raft? Briefly explain.

Q: Fill a U-tube with water and the level in both ends is the same. Water seeks its own level. Why?

Q: Distinguish between pressure and force in the case of weighing yourself on a common bathroom scale.

Q: The Bernoulli effect causes fast-moving vans on the highway to be drawn together when A) air speeds up in passing between them. B) air between them stagnates. C) they experience lift. D) all of the above

Q: When a shower is turned on, the shower curtain moves towards the water spray. This partly involves A) capillary action. B) surface tension. C) pressure changes in moving fluids. D) none of the above

Q: A spinning tossed baseball veers off course in the direction of A) crowded streamlines. B) non-crowded streamlines. C) onward-coming streamlines.

Q: A spinning tossed baseball veers off course in the direction of A) reduced air pressure on the ball. B) increased air pressure on the ball. C) non-crowded streamlines.

Q: If you blow air between a pair of closely-spaced Ping-Pong balls suspended by strings, the balls will swing A) toward each other. B) apart from each other. C) away from the airstream.

Q: The Bernoulli effect causes passing ships to be drawn together when the ships are close and moving in A) the same direction. B) opposite directions. C) either of these D) none of the above

Q: Wind blowing over the top of a hill A) increases atmospheric pressure there. B) decreases atmospheric pressure there. C) has no affect on atmospheric pressure there.

Q: An umbrella tends to jerk upward on a windy day principally because A) air gets trapped under the umbrella, which warms, and rises. B) buoyancy increases with increasing wind speed. C) air pressure is reduced over the curved top surface. D) all of the above

Q: The tarp covering on a trailer or truck puffs upward for fast-moving vehicles, which illustrates A) Pascal's principle. B) Archimedes' principle. C) the principle of continuity. D) Bernoulli's principle.

Q: Airplane lift is achieved when air pressure on the bottom of its wings is A) greater than pressure on top. B) less than pressure on top. C) the same as pressure on top.

Q: If air speed is greater along the top surface of a bird's wings, pressure of the moving air there is A) unaffected. B) less. C) more. D) turbulent.

Q: Airplane flight best illustrates A) Archimedes' principle. B) Pascal's principle. C) Bernoulli's principle. D) Boyle's law.

Q: According to the principle of continuity, the velocity of a fluid multiplied by the cross-sectional area through which it flows at one point will equal the product of A) velocity and cross-sectional area at another point. B) velocity and pressure at another point. C) a constraint factor. D) none of the above

Q: The principle of continuity states that for fluid flow to be continuous it must A) speed up in narrow regions of flow. B) slow down in wide regions of flow. C) both of these D) neither of these

Q: When air gains speed in sweeping across a rooftop its internal pressure is A) reduced. B) unaffected. C) increased.

Q: The internal pressure of a fluid that gains speed A) increases. B) remains unchanged. C) decreases.

Q: As water in a confined pipe speeds up, the pressure it exerts against the inner walls of the pipe A) increases. B) decreases. C) remains constant if flow rate is constant. D) none of the above

Q: An inverted empty jar is pushed downward into water so that trapped air inside can't escape. As it is pushed deeper, the buoyant force on the jar A) increases. B) decreases. C) remains the same.

Q: A large block of wood and a small block of iron each register 2000 N on a weighing scale. Taking buoyancy of air into account, which has the greater mass? A) wood B) iron C) both the same

Q: Suppose you stand on a weighing scale and all of a sudden the atmosphere vanishes. The reading on the scale would A) increase. B) decrease. C) remain the same.

Q: Compared with the buoyant force of the atmosphere on a 1-kg helium-filled balloon, the buoyant force of the atmosphere on a nearby 1-kg solid wood block is A) considerably less. B) considerably more. C) the same.

Q: Compared with the buoyant force of the atmosphere on a helium-filled balloon, the buoyant force of the atmosphere on a nearby wood block of the same volume is A) considerably less. B) considerably more. C) the same.

Q: As a high-altitude balloon sinks lower and lower into the atmosphere it undergoes a decrease in A) volume. B) density. C) weight. D) mass. E) none of the above

Q: A common 5-L metal can will float in air if it is A) evacuated of air. B) filled with a very large amount of helium. C) thrown high enough into the air. D) Nonsense! Unless the can and displaced air weigh the same, the can can't float in air.

Q: An object in a vacuum has no A) buoyant force. B) mass. C) weight. D) temperature. E) all of the above

Q: A bubble of air released from the bottom of a lake A) rises to the top at constant volume. B) becomes smaller as it rises. C) becomes larger as it rises. D) alternately expands and contracts as it rises. E) none of the above

Q: As a helium-filled balloon rises in the air, it becomes A) bigger. B) more dense. C) heavier. D) all of the above E) none of the above

Q: The buoyant force acting on a 1-ton blimp hovering in air is A) zero. B) 1 ton. C) less than 1 ton. D) greater than 1 ton.

Q: A rising balloon is buoyed up with a force equal to the A) weight of air it displaces. B) density of surrounding air. C) atmospheric pressure. D) weight of the balloon and its contents. E) all of the above

Q: A hydraulic press multiplies a force by 100, which is compensated by A) energy, which is divided by 100. B) the lesser distance through which the force acts. C) the time through which the force acts. D) the mechanism providing the force. E) none of the above

Q: To multiply an applied force while using a simple hydraulic lift, your force should be applied to the A) large-diameter piston. B) small-diameter piston. C) relative piston sizes don't matter

Q: In a hydraulic-press operation, it is impossible for the A) output displacement to exceed the input displacement. B) force output to exceed the force input. C) energy output to exceed the energy input. D) output piston's speed to exceed the input piston's speed. E) none of the above

Q: Very importantly, a hydraulic press can multiply A) forces. B) pressures. C) energy. D) all of the above E) none of the above

Q: A hydraulic device has two pistons, one with a small cross-section area and another piston with a larger cross-section area. If a given force is applied to the small piston, the output force on the larger-area piston will be A) less. B) the same. C) greater. D) all of the above E) none of the above

Q: If a pressure of 20 kPa is applied to one piston in a simple hydraulic device, the pressure on a piston of larger area will be A) less than 20 kPa. B) the same 20 kPa. C) more than 20 kPa. D) all of the above E) none of the above

Q: An important underlying feature of hydraulic devices is the conservation of A) pressure. B) momentum. C) energy. D) all of the above E) none of the above

Q: A change in pressure at any point in a confined fluid at rest is transmitted A) undiminished to all points in the fluid. B) to points of lower pressure. C) in the direction of lower energies. D) all of the above E) none of the above

Q: Pascal's principle applies to A) liquids. B) gases. C) both of these D) neither of these

Q: It would be easier to pull evacuated Magdeburg hemispheres apart if they were A) held upside down. B) at sea level. C) 2 km beneath the ocean surface. D) 2 km above the ocean surface. E) none of the above

Q: Evacuated Magdeburg hemispheres are each A) sucked together. B) pushed together by the atmosphere. C) held together by tension.

Q: Consider two vertical tubes of equal cross-section area, one containing water and the other mercury. If the liquid pressures at the bottom of the tubes are equal, both liquids would have equal A) volumes. B) densities. C) weights. D) number of molecules. E) none of the above

Q: Consider two mercury barometers, one with twice the cross-section area of the other. Mercury in the wider tube will rise A) to the same height as in the narrow tube. B) twice as high as mercury in the narrow tube. C) four times as high as mercury in the narrow tube. D) more than four times as high as in the narrow tube. E) none of the above

Q: A column of contained air extends from sea level to the top of the atmosphere. The contained air has mass. If the column instead contained the same mass of water, its height would be A) 1/13.6 times as high as the atmosphere. B) about 3/4 m high. C) 10.3 m high. D) about 5.6 km high.

Q: Compared with an alcohol barometer, the column height for a mercury barometer would be A) lower. B) higher. C) the same.

Q: Compared with a mercury barometer, the column height for a water barometer would be A) lower. B) higher. C) the same.