Chapter 10 Temperature and Heat

Thermal Energy

Heat energy.

What temperature does water freeze and boil at? (in F)

32°F and boils at 212°F.

16. The temperature of 500 g of water is to be raised from 10 °C to 40 °C. The energy needed to do this is about A. 5 ×103 cal. B. 1.5 ×104 cal. C. 2 ×104 cal. D. 4 ×104 cal.

B. 1.5 ×104 cal.

23. A certain amount of heat is transferred to a system, and the system performs some work on its surroundings. The amount of work done is less than the heat added. Thus A. the internal energy of the system increased. B. the internal energy of the system decreased. C. there has been a violation of the principle of conservation of energy. D. an error has been made somewhere. E. there must have been a phase change.

A. the internal energy of the system increased.

Thermometer

A tool to measure temperature by using expansion of liquid alcohol or mercury to indicate changes in temperature.

Specific Heat

A value that measures how much energy is needed to raise 1 kg of a substance 1K. These are fixed values for a given substance. If something has a high specific heat it requires more energy to heat it up. If something has a low specific heat it requires less energy to heat it up. EX: Specific heat of water is 4186 J/kg·K. Which means it takes 4186 J of energy to heat up 1 kg of water to Kelvin.

2. After I dip a cup of water from the ocean, I can conclude that A. the temperature of the water in the cup is the same as the temperature of the water in the ocean. B. the temperatures are the same but the water in the cup has more energy C. the ocean temperature is higher because it has more molecules in it. D. the ocean temperature is higher because it never loses its heat.

A. the temperature of the water in the cup is the same as the temperature of the water in the ocean.

35. A student uses a thermometer calibrated in Kelvin units. A temperature change of 10K is equivalent to a change of how many degrees on the Celsius scale?

Answer: 10

36. The internal energy of a system such as helium gas can be identified as the total mechanical energy of the ______________.

Answer: atoms

25. An ice cube of mass 100 g and at 0oC is dropped into a Styrofoam cup containing 200 g of water at 25oC. The heat of fusion of ice is 80 cal/g and the specific heat capacity of water is 1.0 cal/g C°. Assuming the cup doesn't exchange any heat, the final temperature of the system will be which of the following? A. -10oC. B. 0oC. C. +2.5oC. D. +5.0oC. E. +10oC.

B. 0 C.

13. A mixture consists of 60 g of ice and 40 g of liquid water, both at 0°C. The amount of heat that must be added to melt all of the ice is about A. 3200 cal. B. 4000 cal. C. 4800 cal. D. 8000 cal.

C. 4800 cal.

28. A physics student has to make a choice in the color of shingles to put on her house. Considering only energy cost in heating and cooling the house, the decision of a light versus dark color roof will be based upon which of the following? A. A dark roof would be better in the winter but worse in summer. B. A light roof would be better in the winter but worse in summer. C. A light roof would be better in both the winter and summer. D. A dark roof would be better in both the winter and summer.

C. A light roof would be better in both the winter and summer.

19. Four samples of steel, lead, alcohol and glass all have the same mass and are all initially at 20oC. After 100 calories of heat is added to each sample, the final temperatures are 38.2oC for the steel, 85.6oC for the lead, 23.4oC for the alcohol, and 30oC for the glass. Which of these four materials has the largest specific heat capacity? A. The steel. B. The lead. C. The alcohol. D. The glass. E. All have same heat capacity, since all absorbed 100 cal of heat.

C. The alcohol.

Celsius

Common scale of temperature that most countries use besides the US. Water boils at 100° and freezes at 0°.

Fahrenheit

Common scale of temperature used in the US where water boils at 212° and freezes at 32°.

30. The temperature of a 50 g sample of aluminum is raised from 20oC to 90oC when 770 cal of heat is added. The specific heat capacity of the aluminum is A. not calculable from this data B. 0.11 cal/g Co. C. 15.4 cal/g C°. D. 0.22 cal/g C°. E. 0.91 cal/g C°.

D. 0.22 cal/g C°.

29. Which of the following units is not an energy unit? A. Calorie. B. Joule. C. Kilowatt-hour. D. Horsepower. E. Kilocalorie.

D. Horsepower.

20. On a cold day, a metal fence post feels colder to the touch than a tree. This sensation of different temperatures is explained by the fact that A. the temperature of the tree is higher. B. the specific heat capacity of wood in the tree is higher. C. the specific heat capacity of the metal is higher. D. the thermal conductivity of the wood in the tree is higher. E. the thermal conductivity of the metal is higher.

E. the thermal conductivity of the metal is higher.

Work and Heat both...

Involve energy transfers and are mechanical processes. EX:rub your hands together.

Celsius to Kelvin

K=°C+273

Conductors

Materials that allow heat energy to transfer easily, which will heat up and cool down quickly. Metals are good conductors and gases are poor ones.

Central Heat

Most buildings are heated with this system. A furnace will burn a type of fuel to heat up water, steam, or air. Then it is circulated around the building to warm it up.

Kelvin

Scale of temperature based off of the absolute zero. 0 of this is absolute zero. There are no negative temperatures in this scale.

Heat Transfer

The greater the difference in the temperatures of the two objects, the more energy that will transfer as heat.

What happens when temperature increases in an object?

The object expands.

Heat

The transfer of energy between particles of two objects due to temperature difference between to objects. Always takes place at a higher temperature to a lower temperature.The greater the difference in temperatures of two objects, the more energy that will transfer heat. EX: Heat leaves your hand, things aren't cold.

Radiation

The transfer of heat energy by electromagnetic waves that does not require matter. EX: In a vacuum(empty space).

Convection

The transfer of heat energy by the movement of fluids- as a liquid or gas. Convection currents are created. EX: Roasting marshmallows.

Conduction

The transfer of heat energy within a substance or two substances in contact. EX:Holding a metal pipe.

Passive Solar

This does not require extra energy to work. Skylights and windows work as passive solar heating systems.

Fahrenheit to Celsius Equation

°C=5/9(°F-32)

1. The temperature of a substance is A. proportional to the average kinetic energy of the molecules in a substance. B. equal to the kinetic energy of the fastest moving molecule in the substance. C. proportional to the lowest kinetic energy available to a molecule. D. proportional to the average momentum of the fastest 50% of the molecules in the substance.

A. proportional to the average kinetic energy of the molecules in a substance.

Celsius to Fahrenheit Equation

°F=(9/5°C+32)

17. Which of the following temperatures is the lowest? A. 0 C B. 0F C. 263K D. All are the same.

B. 0 F

33. Heat will not be transferred between two bodies that are at the same ____________________.

Answer: temperature

11. Objects A and B are at the same temperature. Object A now has its temperature increased by one Celsius degree, while B has its temperature increased by one Fahrenheit degree. Which object now has higher temperature? A. Object A. B. Object B. C. Both have the same temperature. D. Impossible to tell from this data.

A. Object A.

7. Two identical objects, one light colored and the other dark colored are at the same cool temperature. Then, you place them outside, on a warm day, in direct sunlight. Which object will warm up faster? A. The dark one. B. The light one. C. Both warm up at the same rate. D. As strange as it seems, neither object will ever warm up because energy conservation prevents the addition of energy.

A. The dark one.

27. Hot cider is poured into a metal cup. Shortly thereafter the handle of the cup becomes hot. This is due to the process of A. conduction. B. convection. C. radiation. D. osmosis.

A. conduction.

6. Two identical objects, one light colored and the other dark colored, are at the same elevated temperature, 50°C. You now plop (yes, plop) them down in a dark, much cooler room. Which object will reach the room's temperature first? A. dark colored B. light colored C. Both reach room temperature at same time. D. As strange as it seems, neither object will ever reach room temperature because energy conservation prevents the loss of energy.

A. dark colored

34. The transfer of heat from a furnace to the house through ducts is by the process of _________________.

Answer: convection

32. The first law of thermodynamics is an extension of the principle of conservation of _________________ that we first met in mechanics.

Answer: energy

31. During a phase change the ___________________ of a system will remain constant as heat is added.

Answer: temperature

14. While studying for this quiz you realize that you still have 100 g of lukewarm coffee at 40°C left in a paper cup. When you pour 50 g of boiling water into the cup, the temperature of the resulting coffee-like mixture will be now A. 50 °C. B. 60 °C. C. 67 °C. D. 70 °C. E. 80 °C.

B. 60 °C.

Insulators

Materials that are poor conductors that do not allow heat energy to transfer easily. Solids like wood, rubber, liquids, and gases are good insulators.

8. The lowest possible temperature a body can approach is called A. "mighty" cold. B. absolute zero. C. triple absolute zero. D. triple point. E. critical temperature.

B. absolute zero.

3. Heat is a form of energy, and it has long been known that heat energy will naturally flow A. from cold to hot objects. B. from hot to cold objects. C. only from solids to liquids. D. only from liquids to solids. E. only from gases to solids and liquids.

B. from hot to cold objects.

26. Heat is added to an ideal gas and the gas expands. In such a process the temperature A. must always increase. B. will remain the same if the work done equals the heat added. C. must always decrease. D. will remain the same if work done is less than the heat added. E. will remain the same if the work done exceeds the heat added.

B. will remain the same if the work done equals the heat added.

24. Compare the internal energy of one gram of steam to that of one gram of water if both are at 100° C. A. The internal energy of the water and steam are the same. B. The internal energy of the water will be higher. C. The internal energy of the steam will be higher.

C. The internal energy of the steam will be higher.

5. On a cold winter's morning you awake and step out of bed. One foot is on the tile floor and the other is on a rug on the floor. Which statement is true? A. The tile feels colder than the rug because it really is colder than the rug B. Heat flows from the rug, thru your body and out to the tile - thus the tile feels cold compared to the rug C. The tile feels colder than the rug, because compared to the rug, the tile conducts heat more rapidly away from your foot. D. Actually there is no difference between the rug and the tile so any sensation you experience is imaginary.

C. The tile feels colder than the rug, because compared to the rug, the tile conducts heat more rapidly away from your foot.

18. Absolute zero is the temperature A. on the coldest day recorded at Nome, Alaska. B. of the freezing point of water. C. at which an ideal gas would exert zero pressure. D. of the boiling point of liquid helium. E. of the freezing point of mercury.

C. at which an ideal gas would exert zero pressure.

10. When the temperature of the air in a balloon is lowered, the volume of the balloon A. increases. B. stays the same. C. decreases. D. expands.

C. decreases.

22. During the course of a demonstration the professor is called away. When he returns he finds a beaker of water that was at room temperature is now at a slightly higher temperature. There is a stirring rod on the desk and a cigarette lighter. The professor can assume that the temperature increase is due to A. heat added to the system. B. mechanical work done on the system. C. either heat added or mechanical work done.

C. either heat added or mechanical work done.

15. A box of graham crackers is labeled "120 Calories per serving". Assuming this means 120 kcal, the energy of a serving of the graham crackers is about A. 120 J. B. 4.2 ×103 J. C. 5 ×104 J. D. 5 ×105 J.

D. 5 ×105 J.

9. Water freezes at 273° on the ________ scale. A. Fahrenheit B. Celsius C. Rankin D. Kelvin E. Vernier

D. Kelvin

21. The term heat in physics is A. equivalent to temperature. B. equivalent to internal energy. C. any energy transferred to a body that raises the temperature of the body. D. energy transferred to a body because of a difference in temperature. E. the same as work.

D. energy transferred to a body because of a difference in temperature.

4. The amount of heat is often measured in calories. If I add 1 calorie of heat energy to 1 gram of water, the temperature of the water will A. decrease by 1°C. B. decrease by 1°F. C. stay the same since water has a very high specific heat. D. increase by 1°C. E. increase by 1°F.

D. increase by 1°C.

12. The three processes by which heat energy is transferred between objects are A. heat, calorie and radiation. B. radiation, temperature, and convection. C. absorption, radiation, and convection. D. radiation, convection, and conduction. E. radiation, absorption, and conduction.

D. radiation, convection, and conduction.

Solar Heat

Solar panels collect energy from the sun, which heats water that is pumped throughout the buliding. This is an active solar heating system.

Temperature

The measure of average kinetic energy of all particles within an object.*As kinetic energy rises, temperature rises; as kinetic energy decreases temperature decreases.

Heating System

Transfer of energy to a substance to raise the temperature of the substance. Most involve heating air or water. EX: Body is an example of this, nutrients in food heat your blood when surrounded by cold air.

Specific Heat Equation

energy=specific heat·mass·temperature change. Q=cmΔt. Measured in Joules.