# Physics Ch. 15 Questions

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What are the temperatures for freezing water on the Celsius and Fahrenheit scales? For boiling water?
Water freezes at 0Â°C//32Â°F water boils at 100Â°C//212Â°F
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What are the temperatures for freezing water and boiling water on the Kelvin temperature scale?
water freezes at 273 K water boils at 373 K
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What is meant by "translational" kinetic energy?
Kinetic energy of motion that carries a molecule from one place to another (random molecular motion) defines Temperature temperature is proportional to translational kinetic energy
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Which forms of energy determine temperature? Translational kinetic energy, rotational kinetic energy, vibrational kinetic energy, or all of these?
Translational Kinetic Energy determines Temperature. Vibrational KE and Rotational KE (plus potential energy) contribute to overall energy of the substance.
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What is meant when we say that a thermometer is in thermal equilibrium with another object?
Heat no longer flows between the object and thermometer when both are at the same temperature. *When it is in thermal contact with something to be measured, energy will flow between both until their temps are equal; thermal equilibrium is established.
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Is there a distinction between thermal energy and internal energy? Which term do physicists prefer?
Thermal energy emphasizes heat flow (link between heat and temperature), whereas internal energy is the grand total of all energies inside a substance. Physicists prefer internal energy. *heat: energy in transit. Once transferred, it is no longer heat.
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In which direction does heat flow spontaneously between hot and cold objects?
From high temperature to low temperature. Ex.) touching ice; energy transfers from warm skin to cooler ice. *Heat: energy in transit. Once transferred, it is no longer heat.
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Does a hot object contain internal energy or does it contain heat?
A hot object contains nternal energy, not heat. Object contains translational KE of jostling molecules, rotational KE and other KE and PE from molecular forces.
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How is heat similar to and different from internal energy?
They are both forms of energy, but heat flows, whereas internal energy does not. Internal energy is only summation of all the substance's energies.
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What role does temperature have in the direction of heat flow?
Heat flows spontaneously from high temperature to low temperature.
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How is the energy value of foods determined?
The food is burned and the energy released is measured.
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Distinguish between a calorie and a Calorie.
A Calorie is 1000 calories.
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Distinguish between a calorie and a joule.
1 calorie = 4.19 joules
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How many joules (J) are needed to change the temperature of 1 gram of water by 1Â°C?
4.19 J
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Which warms up fastest when heat is applied: water, iron, or silver?
Silver warms up faster than iron. Iron warms up faster than water. Ag: lowest specific heat capacity Fe: low spec heat capacity H2O: high spec heat capacity
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Does a substance that heats up quickly have a high or a low specific heat capacity?
A low specific heat capacity heats up quickly cools off quickly
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Does a substance that cools off quickly have a high or a low specific heat capacity?
A low specific heat capacity
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How does the specific heat capacity of water compare with the specific heat capacities of other common materials?
Water has a higher specific heat capacity than most common materials.
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Northeastern Canada and much of Europe receive about the same amount of sunlight per unit area. Why, then, is Europe generally warmer in the winter?
The gulf stream carries warm, high heat capacity water past the west coast of Europe.
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According to the law of conservation of energy, if ocean water cools, then something else should warm. What is it that warms?
The cooling ocean warms the air.
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Why is the temperature fairly constant for landmasses surrounded by large bodies of water?
Water has a high specific heat capacity.
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Why do substances expand when their temperature is increased?
Higher-temperature substances have greater molecular motion.
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Why does a bimetallic strip bend with changes in temperature?
The two metals expand at different rates.
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Which generally expands more for an equal increase in temperature: solids or liquids?
Liquids generally expand more than solids. *H2O ice is the weird one!
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When the temperature of ice-cold water is increased slightly, does it undergo a net expansion or a net contraction?
Contraction ice cracks, tries to shrink
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Why is ice less dense than water?
Ice crystallizes with an open structure, and the gaps that form between the water molecules in ice increase its volume.
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Does "microscopic slush" in water tend to make it more dense or less dense?