Q&A Hero

Q: The temperature at which water freezes is the same as the temperature at which A) ice melts. B) water boils in a pressure cooker. C) both of these D) neither of these

Q: The addition of salt to water affects its A) crystal composition. B) freezing point. C) viscosity. D) liquidity. E) none of the above

Q: An inventor discovers a harmless and tasteless salt, which when added to water changes its boiling point. The market value for this salt will be better if the salt A) lowers the boiling point of water. B) raises the boiling point of water. C) either raises or lowers the boiling point, as the food would be cooked either way. D) none of the above

Q: Water in a car radiator sometimes boils explosively when the radiator cap is removed, which is due to sudden A) rapid evaporation. B) reduced pressure. C) excess condensation. D) excess vaporization.

Q: In one word, how can water in the power plant of a nuclear submarine far exceed 100C? A) conductivity B) evaporation C) condensation D) pressure E) vaporization

Q: A good cook knows that the temperature of violently boiling water is A) higher than that of simmering water. B) the same as that of simmering water. C) actually lower than 100oC. D) neither of the above

Q: Water can be turned to ice by A) lowering the surrounding air pressure. B) extracting energy. C) both of these D) neither of these

Q: Hydrothermal vents deep beneath the ocean surface attain temperatures far above 100C due to A) higher salt content. B) reduced salt content. C) greater pressure. D) all of the above E) none of the above

Q: A geyser such as Old Faithful in Yellowstone Park is similar to a A) vacuum bottle. B) canteen. C) coffee percolator. D) teakettle. E) vat of molten lead.

Q: Compared to sea level, water in an open pot in the mountains boils at A) a higher temperature. B) a lower temperature. C) the same temperature. D) none of the above

Q: Increased air pressure on the surface of hot water tends to A) prevent boiling. B) promote boiling. C) both of these D) neither of these

Q: For increased atmospheric pressure, the boiling point of water A) goes down. B) rises. C) remains at 100 degrees C.

Q: When heat is added to boiling water, its temperature A) increases. B) decreases. C) remains unchanged. D) none of the above

Q: Water can be brought to a boil by A) applying heat. B) reducing air pressure on its surface. C) both of these D) neither of these

Q: Compared with sea-level cooking, in cooking eggs by boiling in mountain regions you should boil the eggs A) with a hotter flame. B) for a shorter time. C) for a longer time. D) all of the above E) none of the above

Q: In mountain regions, food cooked in boiling water cooks slower than when cooked at sea level. If the temperature beneath the pot of boiling water is increased, the food will cook A) faster. B) slower still. C) both of these D) neither of these

Q: Food in a pressure cooker is cooked faster due to A) higher temperature. B) greater rate of bubble formation in the water. C) energy transfer in the water. D) all of the above E) none of the above

Q: Morning dew on the grass is a result of A) evaporation of water. B) the open-structured form of water crystals. C) air pressure on water vapor. D) slow-moving water molecules sticking to one another.

Q: On a muggy day, water molecules in the air that strike our bodies A) transfer some of their kinetic energy to us. B) gain kinetic energy as they change phase. C) form an insulating layer on our bodies.

Q: We feel uncomfortably warm on a muggy day because water molecules are A) evaporating from our moist bodies. B) condensing on our bodies. C) evaporating and condensing on our bodies at the same rate. D) none of the above

Q: Steam burns are more damaging than burns caused by boiling water because steam A) has more energy per gram than boiling water. B) releases additional energy when it condenses. C) both of these D) neither of these

Q: A boy scout will be burned more severely by A) 100 g of water at 100C. B) 100 g of steam at 100C. C) both about equally D) neither of these

Q: Evaporation is a cooling process and condensation is A) a warming process. B) a cooling process also. C) neither of these

Q: When a geyser erupts, pressure at its bottom A) increases. B) decreases. C) is unaffected D) all of the above E) none of the above

Q: The pressure at the bottom of a geyser is A) less than nearer the top. B) the same as nearer the top C) greater than nearer the top. D) all of the above E) none of the above

Q: The main difference between a fog and a cloud is A) water vapor content. B) density of vapor. C) seeding. D) altitude. E) temperature.

Q: When slow-moving water molecules collide they tend to A) rebound without sticking. B) stick. C) both of these D) neither of these

Q: When fast-moving water molecules collide they tend to A) rebound without sticking. B) stick. C) both of these D) neither of these

Q: The toy drinking bird nicely illustrates A) evaporation. B) condensation. C) both of these D) neither of these

Q: Double-pane windows contain nitrogen rather than air to prevent A) gas escape. B) thermal conduction. C) condensation. D) heat flow.

Q: A canteen that is wet on the outside results in water inside that is A) warmer. B) cooler. C) both of these D) neither of these

Q: What occurs in a pan of water placed outdoors on a warm day? A) evaporation B) condensation C) both of these D) neither of these

Q: The surface of hot water has a relatively high rate of A) evaporation. B) condensation. C) conductivity. D) convection.

Q: A hot dog pants A) to enable evaporation in its mouth and bronchial tract. B) to provide more oxygen into its lungs. C) to impress dogs of the opposite sex. D) none of the above

Q: When you blow over hot soup to cool it you are helping A) to slightly increase air pressure atop the soup surface. B) more energetic particles in the soup to escape. C) conduction, convection, and radiation. D) none of the above

Q: The reason that evaporation is a cooling process is A) radiation of heat during the process. B) due to conduction and convection. C) the more energetic molecules escape the liquid. D) all of the above E) none of the above

Q: The molecules in a room-temperature glass of water jostle around at A) a great variety of speeds. B) much the same rates of speed. C) a very small range of speeds.

Q: Wrapping a hot potato in aluminum foil significantly reduces the rate at which it cools by A) conduction. B) condensation. C) evaporation. D) melting.

Q: To save energy while you leave your cool house for a half hour on a hot day, turn the temperature setting on the air conditioner A) down. B) up. C) off altogether. D) to room temperature.

Q: To save energy while you leave your warm house for a half hour on a cold day, turn the thermostat A) down. B) up. C) to room temperature.

Q: Hydrogen and oxygen molecules in a sample of gas have the same temperature. This means the hydrogen molecules, on average, have the same A) speed and the same kinetic energy. B) speed, but more kinetic energy. C) speed, but less kinetic energy. D) kinetic energy, but more speed. E) kinetic energy, but less speed.

Q: When a hot object makes thermal contact with a cold object, the direction of A) temperature is from hot to cold. B) internal energy flow is from hot to cold C) both of these D) neither of these

Q: A Thermos bottle has double glass walls with silver coating on the glass surfaces that face each other. The silver coating reduces energy transfer by A) conduction. B) convection. C) radiation. D) all the above E) none of the above

Q: Heat normally flows from objects of high A) internal energy to objects of low internal energy. B) temperature to objects of low temperature. C) both of these D) neither of these

Q: When coal dust is spread on snow on a sunny day A) more melting occurs. B) less melting occurs. C) no change in melting rate occurs.

Q: Substances absorb heat energy by the process of A) conduction. B) convection. C) radiation. D) all of the above

Q: The solar constant for Earth is A) 0.7 kW/m2. B) 1.0 kW/m2. C) 1.4 kW/m2. D) more than 1.4 kW/m2.

Q: The solar constant is the A) input of solar energy per square meter atop Earth's atmosphere. B) difference between solar energy atop the atmosphere and that reaching ground. C) maximum amount of energy Earth receives from the Sun.

Q: Solar power is the rate at which A) the Sun emits energy. B) solar energy is received from the Sun. C) the atmosphere absorbs energy. D) all of the above E) none of the above

Q: The amount of solar energy per square meter atop the atmosphere at right angles to the Sun's rays is about A) 700 joules. B) 1000 joules. C) 1400 joules. D) much more than 1400 joules.

Q: Solar power is used in many parts of the world for A) heating water. B) generating electricity. C) both of these D) neither of these

Q: The heat we enjoy on a sunny day is due mainly to the Sun's A) high surface temperature. B) relatively close distance. C) enormous size. D) none of the above

Q: Looking forward, common consensus will likely agree that the wisest use of fossil fuels is to A) convert them to heat and smoke. B) save them for tomorrow's materials. C) extract and sell them as quickly as possible. D) all of the above

Q: Every equation in physics reminds us of a lesson: we can never change only one thing. When we change the composition of the atmosphere we likely also change A) its transparency. B) its reflectivity. C) its average temperature. D) Earth's climate. E) all of the above

Q: If the composition of the upper atmosphere were altered to permit a greater amount of terrestrial radiation to escape, Earth would be A) cooler. B) warmer. C) quite unaffected. D) none of the above

Q: Long ago a runaway greenhouse effect transformed the planet A) Mercury. B) Venus. C) Mars. D) all of the above

Q: Which is the most abundant greenhouse gas in Earth's atmosphere? A) nitrogen. B) water vapor. C) carbon dioxide. D) none of the above

Q: If there were no greenhouse effect, Earth's average temperature would likely be A) near absolute zero. B) a frigid -18C. C) comfortably cooler. D) warmer than now.

Q: Glass in a florist's greenhouse acts as a one-way valve in that it A) lets light energy flow only in one direction. B) cuts off unwanted radiation. C) allows high-frequency waves in and blocks low-frequency waves exiting. D) is transparent only to lower-frequency waves.

Q: The planet Earth loses heat primarily by A) conduction. B) convection. C) radiation. D) all of the above

Q: Waves emitted by the Sun and terrestrial wave emissions are A) the same except for their frequencies and wavelengths. B) entirely different kinds of waves. C) identical.

Q: Which body glows with electromagnetic waves? A) the Sun B) the Earth C) you and your classmates D) all of the above

Q: When you're ready for the hottest sips of coffee, add cream A) right away. B) at any time. C) when you are ready to drink the coffee.

Q: It is commonly thought that a can of beverage will cool faster in the coldest part of a refrigerator. Knowledge of Newton's law of cooling A) supports this common knowledge. B) contradicts this common knowledge. C) is unrelated to this common knowledge.

Q: A blueberry pie will be a net absorber of energy when its temperature is A) higher than its surroundings. B) lower than its surroundings. C) none of these

Q: An apple pie will be a net emitter of energy when its temperature is A) higher than its surroundings. B) lower than its surroundings. C) none of these

Q: A red-hot piece of coal will cool quicker in a A) cold room. B) warm over. C) both the same.

Q: Newton's law of cooling applies to objects undergoing A) cooling. B) warming. C) both of these D) neither of these

Q: Both black and white road surfaces radiate energy. At midnight on a starry night the warmer road surface is the A) black surface. B) white surface. C) neither, as no noticeable difference.

Q: Both black and white road surfaces absorb sunlight. The warmer road surface at the end of a sunny day is the A) black surface. B) white surface. C) neither of these

Q: If a poor absorber of radiation were a good emitter, its temperature would be A) less than its surroundings. B) more than its surroundings. C) the same as its surroundings.

Q: A good reflector of radiation is a A) good absorber of radiation. B) good emitter of radiation. C) poor absorber of radiation. D) none of the above

Q: A good absorber of radiation is a A) good emitter of radiation. B) poor emitter of radiation. C) good reflector. D) none of the above

Q: A photovoltaic cell receives energy input by A) conduction. B) convection. C) radiation. D) all of the above

Q: The temperature of outer space is A) zero. B) about 2.7 kelvin. C) meaningless. D) none of the above

Q: A bridge is more likely to be ice covered than the roadway on a cold day because A) a bridge is more conducting than ground. B) a bridge is more commonly wet than ground. C) heat upwelling from the ground below is absent on a bridge. D) none of the above

Q: A liter of cold water will warm faster in sunlight in a A) black pot. B) silver pot. C) red pot. D) none of the above

Q: A liter of hot water will cool to room temperature faster in a A) black pot. B) silver pot. C) red pot. D) none of the above

Q: If a pizza absorbs more energy than it emits, its temperature A) decreases. B) is unaffected. C) increases. D) none of the above

Q: If a pizza radiates more energy than it absorbs, its temperature A) decreases. B) is unaffected. C) increases. D) none of the above