Quest Chapter 21. More heat energy means more of what type of energy? Does the mass change? So, what must change? What is the same in both containers?

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1 1 When a container of gas is heated, what happens to the average speed of its molecules? 1. Additional information is needed. 2. increases 3. doesn t change 4. decreases 2 (part 1 of 3) Two glasses of water contain different volumes of water at the same temperature. In which glass are the water molecules moving faster? 1. Unable to determine 2. Same speed in both 3. B 4. A 3 (part 2 of 3) Which glass contains more thermal energy? 1. Same in both 2. B 3. A 4. Unable to determine 4 (part 3 of 3) Which glass requires more heat to increase its temperature by 1 C? 1. A 2. B 3. Unable to determine 4. Either Quest Chapter 21 More heat energy means more of what type of energy? Does the mass change? So, what must change? What is the same in both containers? What is different? What determines the speed of the molecules in a liquid? How do we determine thermal energy? Raising temperture requires what? To raise it one degree requires what? 5 (part 1 of 2) A wooden block is released from rest at the top of a frictionless inclined plane and slides down to the bottom. What conversions of energy are taking place as the block slides down the inclined plane? 1. No energy conversion takes place. 2. Gravitational potential energy is converted into kinetic energy and thermal energy. 3. Kinetic energy is converted into thermal energy. 4. Gravitational potential energy is converted into kinetic energy. Which one requres more heat? Before released the block has what type of energy? Eliminate answers that do not begin with this. At the bottom, what type of energy does it have? Eliminate answers that do not end with this. Tada!

2 6 (part 2 of 2) What would be your answer if there were friction between the block and the plane? 1. Kinetic energy is converted into thermal energy. 2. Gravitational potential energy is converted into kinetic energy and thermal energy. 3. Gravitational potential energy is converted into kinetic energy. 4. No energy conversion of energy takes place. 7 You use energy to heat your home. What ultimately happens to the energy that you pay for in your heating bill? 1. The energy disappears as it never exists. 2. The energy escapes your home and heats the outside. 3. The energy heats your home. 4. The energy changes to mass. 8 At what common temperature will a block of wood and a block of metal both feel neither hot nor cold to the touch? 1. At room temperature 2. At the freezing point 3. When the temperature of the blocks is lower than the temperature of your hand 4. When the temperature of the blocks is higher than the temperature of your hand 5. When the temperature of the blocks is the same as the temperature of your hand 9 One hundred grams of liquid A is at a temperature of 100 C. One hundred grams of liquid B is at a temperature of 0 C. When the two liquids are mixed, the final temperature is 50 C. What can you say about the specific heats of the two liquids? 1. The specific heat of B is greater than that of A. 2. The specific heat of A is greater than that of B. 3. The specific heats of A and B are equal. With the addition of friction, what other type of energy must be included? Will that delete one of the original types? Heat flows from what to what? Once heat has flowed into your home to raise its temperature, will it stop flowing? What direction is heat flowing if an object feels hot? Cold? What direction is heat flowing if an object feels neither hot nor cold? What does that mean? Hmm Same mass same change in temperature What can we say about the specific heats?

3 10 Two hundred grams of liquid A is at a temperature of 100 C. One hundred grams of liquid B is at a temperature of 0 C. When the two liquids are mixed, the final temperature is 50 C. Which material has a higher specific heat? 1. The specific heat of A is greater than that of B. 2. The specific heat of B is greater than that of A. 3. The specific heats of A and B are equal. 11 Which of the following has the greatest amount of internal energy? 1. a cup of hot coffee 2. a pencil 3. an iceberg 4. a laptop 5. a cup of cold water 12 Consider the following statement: Water has a high specific heat capacity. 1. It s not true. 2. It s always true. A watermelon stays cool for a longer time than sandwiches when both are removed from a cooler on a hot day. 3. It s true only if water is not mixed with other substances; for example, milk would have low specific heat. Twice as much of one is needed to make the same temperature change in both. Hmm Could the specific heats be the same? If not, which one is larger? About what is the question asking? Temperature? No. Temperature is average KE. Mass. NO. Mass is a measure of the amount of matter. Battery charge? NO. Remember: Internal energy includes all forms of energy that are inside something. It will involve the product of the total amount of something and an average measure of that thing. What do you know about water and specific heat? Is that relationship conditional? Does it change?

4 13 Iceland, so named to discourage conquest by expanding empires, is not at all ice-covered like Greenland and parts of Siberia, even though it is close to the Arctic Circle. The average winter temperature of Iceland is considerably higher than in the regions at the same latitude in eastern Greenland and central Siberia. What explains this? 1. Iceland is below sea level. 2. Neither is true. 3. Both are true. 4. The climate of Iceland is moderated by the surrounding water. 14 What is the explanation for the fact that the desert sand is very hot in the day and very cool at night? 1. Sand has a low specific heat compared to air. 2. Sand is a bad heat conductor. 3. Sand reflects light very well. 15 A square hole is cut out of a piece of sheet metal. When the temperature of the metal is raised, the metal expands. What happens to the size of the square hole? Hint: Break up the piece of metal into eight smaller square pieces of sheet metal, then raise the temperature, then put then back together. 1. The hole becomes bigger. 2. The hole becomes smaller. 3. The hole remains the same. 16 Suppose your gold wedding ring became stuck on your finger. Some home remedies suggest soaking your finger in ice water and then trying to remove the ring. If this remedy relies on thermal expansion effects, what does this tell you about the relative expansion coefficients of gold and your finger? 1. More information is needed. 2. The expansion coefficient of your finger is higher. 3. The expansion coefficient of gold is higher. Iceland is an. (Look at a map.) A is surrounded by. What does that do to the climate of Iceland? Does sand change temperature quickly? What does that say about the specific heat of sand? Use the hint that is given in the problem. Remember the goal is to get the ring off your finger. So, you want the ring to get larger relative to your finger.

5 17 Two pieces of copper pipe are stuck together, as shown. One way to separate them is to run water inside the inner pipe and over the outer pipe. Which method is applicable to separate them? 1. Run cold water inside the inner pipe and pour cold water over the outer pipe. 2. Run cold water inside the inner pipe and pour hot water over the outer pipe. 3. Run hot water inside the inner pipe and pour hot water over the outer pipe. 4. Run hot water inside the inner pipe and pour cold water over the outer pipe. 18 Two thin strips of metal (A and B) are glued together at 0 C as shown in the figure. At 20 C they bend upward because the metals expand differently. Which metal, A or B, has a higher thermal expansion coefficient? 19 Imagine two drinking glasses that stick together when put one into the other. Which of the following advice will help separate them? 1. Fill the inner glass with cold water and run hot water over the surface of the outer glass. 2. Fill the inner glass with hot water and run hot water over the surface of the outer glass. 3. Fill the inner glass with cold water and run cold water over the surface of the outer glass. 4. Fill the inner glass with hot water and run cold water over the surface of the outer glass. 5. There is no easy way to separate them. 20 A metal ball is just able to pass through a metal ring. What is correct? 1. When the ball is heated, it will not pass through the ring. 2. When the ring is heated, the size of the hole does not change. 3. When the ring is heated, the size of the hole decreases. 4. When the ball is heated, it will still pass through the ring. 5. When the ring is cooled, the size of the hole increases. What do you want to do? What must you do to the outer piece? What temperature will do that? What must you do to the inner piece? What temperature will do that? Which side is expanding more? It has the higher coefficient of thermal expansion. Same idea as #17. Eliminate the false statements in the answer list if you do not see the answer right away.

6 21 Suppose you cut a small gap in a metal ring, What is correct? 1. The gap in the ring will become narrower when the ring is heated. 2. The gap in the ring will not change when the ring is cooled. 3. The gap in the ring will become wider when the ring is cooled. 4. The gap in the ring will not change when the ring is heated. 5. The gap in the ring will become wider when the ring is heated. 22 When water freezes, it expands. What does this say about the density of ice relative to the density of water? 1. Ice is less dense than water. 2. Ice is as dense as water. 3. Ice is denser than water. 23 What was the precise temperature at the bottom of Lake Superior at 12 a.m. on October 31, 1894? 1. 2 C C 3. 4 C 4. 0 C 5. All are wrong. 24 A steel stick has a length of 89 cm at 33 o C. What is the length of stick at 116 o C? Assume the linear expansion coefficient for steel is K 1. Answer in units of cm What happens to the dimensions of a solid when its temperature increases? Decreases? Eliminate obviously wrong answer choices. What does expansion do to mass? To volume? How does this change affect density? What is the coldest temperature water can reach before it begins to expand? Remember: ΔL = L 0 X α X ΔT Where T is the temperature difference in Celsius(Kelvin). L and ΔL can be in any units but are the same unit (m & m, or inches & inches, etc.) And, α is the coefficient of expansion. 25 The coefficient of linear expansion for a silver strip is / o C. What is its length on a hot day when the temperature is 31 o C if the strip is 1.9 m long when it is 12 o C? Answer in units of m So, the total length is L + ΔL. See the hint for #24.

7 26 A copper telephone wire has essentially no sag between poles 38 m apart on a winter day when the temperature is 18 o C. How much longer is the wire on a summer day when the temperature is 34 o C? Assume that the thermal coefficient of copper is constant throughout this range at its room temperature value of ( o C) 1. Answer in units of cm See the hint for #24.