Quest Chapter 23a. More heat energy means more of what type of energy?

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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 23a 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? Which one requres more heat?

2 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. 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 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! 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?

3 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. 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 Hmm Same mass same change in temperature What can we say about the specific heats? 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.

4 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. 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. What do you know about water and specific heat? Is that relationship conditional? Does it change? 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.

5 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. 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? Remember the goal is to get the ring off your finger. So, you want the ring to get larger relative to your finger. 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.

6 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. 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. Same idea as #17. Eliminate the false statements in the answer list if you do not see the answer right away. What happens to the dimensions of a solid when its temperature increases? Decreases? Eliminate obviously wrong answer choices.

7 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 If you hold one end of a metal nail against a piece of ice, the end in your hand soon becomes cold. Which description is right? 1. Temperature flows from the ice to your hand. 2. Heat flows from the ice to your hand. 3. Energy flows from your hand to the ice. 4. The cold flows from the ice to your hand. 25 Wrap a fur coat around a thermometer. How does the temperature change? 1. It depends on the material of the thermometer. 2. It rises. 3. It rises at first, then drops back to the original. 4. It does not change. 5. It drops. 26 Why is there a layer of copper and aluminum at the bottom of stainless steel cookware? 1. Copper and aluminum are better conductors of heat than stainless steel. 2. There is no reason behind it. 3. Stainless steel transfers heat more quickly to the cookware s interior. 4. Copper and aluminum are bad conductors of electricity. 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? What flows: temperature, heat or energy? What direction does it flow? What do we assume about the conditions of the problem? Since we know nothing else, we must assume that the coat and the thermometer are in a room at that room s temperature. Other than to hold in the contents of the pot, what is the purpose of the bottom of a pot? What type of material will best do that?

8 27 Many have injured their tongues by licking a piece of metal on a very cold day. Which of the following is true? I) Heat transfers quickly to the metal. II) Metal is a good heat conductor. III) Saliva freezes as soon as the tongue touches the metal surface. IV) Licking a piece of wood would result in the same injury. 1. II and IV only 2. I and IV only 3. I and II only 4. II and III only 5. II,III and IV only 6. I,II and III only 7. All of them 8. III and IV only 9. I,II and IV only 10. I and III only 28 Deleted 29 A certain amount of heat is added to some water so that its temperature rises. The same amount of heat is added to a piece of aluminum with the same mass as the water. Which has the higher temperature change? 1. water 2. aluminum 3. They have equal temperature changes. 30 Heat energy from the sun reaches the earth by 1. thermal expansion. 2. convection. 3. conduction. 4. radiation. Select which events are true (I IV), and then choose to the answer that has only those listed. What are the specific heats of water and aluminum? Remember a larger specific heat will have a smaller change in temperature for a certain amount of heat change. What is needed for conduction, convection, and radiation to take place? For energy to move from the sun to the Earth, which transfer methods are eliminated based on what is needed to each transfer type to take place?

9 31 (part 1 of 2) The furnace keeps house A at 25 C, while the furnace in house B keeps it at 20 C. Which house requires heat to be supplied by its furnace at a faster rate? 1. House A requires heat at a slightly faster rate than B. 2. House B requires heat at about four times the rate of A. 3. None of these 4. House B requires heat at about twice the rate of A. 5. House B requires heat at a slightly faster rate than A. 6. House A requires heat at about four times the rate of B. 7. House A requires heat at about twice the rate of B. 8. Houses A and B require heat at the same rate. Remember: You need to pick the best answer not just one that is correct. Consider each house to be identical as far as materials are concerned. This means that the specific heats are the same. Since, Q = mcδt, and m A = m B and c A = c B, what changes the amount of heat, Q, required to maintain the temperature? That s right: ΔT. What is ΔT A and ΔT B? So, what is the relative size of Q A compared to Q B?

10 32 (part 2 of 2) The outside temperature drops to 5 C. The temperature inside house A is still kept at 25 C. Compare the rate at which the furnace must supply heat now to the rate before, when it was 15 C outside. 1. House A requires heat at about four times the rate of B. 2. House B requires heat at about four times the rate of A. 3. House B requires heat at a slightly faster rate than A. 4. House B requires heat at about twice the rate of A. 5. None of the above answers is correct. 6. House A requires heat at a slightly faster rate than B. 7. Houses A and B require heat at the same rate. 8. House A requires heat at about twice the rate of B. 33 Consider the changes of state for a simple water molecule that goes from a solid to a liquid to a gas from the perspective of its average kinetic energy. What statement is true? 1. As the ice melts, the kinetic energy increases. 2. As the ice melts and becomes a gas, the kinetic energy decreases. 3. As the water becomes a gas, the kinetic energy decreases. The only thing that has changed from the previous problem (part 1) is the outside temperature. Redo the calcs and answer the question. What is the difference in motion between a solid, liquid, and a gas?

11 34 Why does blowing over hot soup cool the soup? 1. The air becomes dryer when you blow. 2. Air temperature lowers as you blow. 3. Air temperature is much lower than the soup. 4. Net evaporation increases as does its cooling effect. 35 How would you determine wind direction after wetting your finger and holding it up in the air? 1. It s not a scientific way to determine the wind direction, but rather a silly superstition. 2. If a finger feels cold the wind must be blowing from North. If it feels warm, it s South wind. 3. The side of your finger that feels cold shows where the wind is blowing from. 4. If a finger dries up quickly then it s a tropical South wind. If it takes a while for it to dry it must be a wind from the nearest ocean, full of evaporation, and depends on where you are on the continent. 36 When you step out of a swimming pool on a hot, dry day in the southwest, why do you feel quite chilly? 1. The temperature outside the swimming pool is much lower. 2. The temperature drops dramatically when you finish swimming. 3. The temperature doesn t change at all; it is all in your mind. 4. The water evaporates rapidly in the dry air, gaining its energy from your skin, which is cooled. Blowing OVER the hot soup does something or we would not do it. How does the moisture in your breath compare to normal air? How does the temperature of your breath (from inside you) compare to the temperature of the air? What might blowing move from the atmosphere above the soup when you blow? OK, if you don t know the answer to this Go OUTSIDE and try it. There does need to be a breeze blowing. Hot, dry? What happens to the water on the surface of your body when exposed to hot DRY air? What happens to your temperature when that happens?

12 37 A great amount of water vapor changes phase to become water in the clouds that form a thunderstorm. Does this release thermal energy or absorb it? 1. Absorb energy; water is heavier than water vapor. 2. Release energy; water vapor undergoes condensation. 3. Absorb energy; water vapor cools to become water. 4. Release energy; some of the water molecules lose their energies. 38 Why does the temperature of boiling water remain the same as long as the heating and boiling continue? 1. When water boils, it is being cooled by the boiling process as fast as it is being heated by the stove. 2. The stove stops working when the water is boiling. 3. The water and the stove have the same temperature. 4. The cold air around the water takes away the heat given by the stove. Water vapor changes phase to what? Liquid water. What is the direction of the energy flow when a gas changes to a liquid. What is the boiling process? It is an active phase change in which a liquid becomes a gas. This is like evaporation being driven by energy flowing into the liquid. The energy flowing into the liquid that is at the boiling point goes to evaporate particles in the liquid which makes them into a gas at the same temperature as the surrounding liquid. 39 Why are icebergs often surrounded by fog? 1. The chilled air in the vicinity of an iceberg results in condensation of water vapor in the air (fog). 2. The air is dryer near an iceberg. 3. The evaporation from an iceberg condenses into droplets (fog). 4. An iceberg attracts vapor from the surrounding air. Select the answer that best describes this process. What happens to air near something that is really cold? What happens to water vapor in that type of environment?

13 40 When water freezes 1. heat is absorbed from the surroundings. 2. there is no heat exchange with the surroundings. 3. heat is given off to the surroundings. 4. the temperature of the water decreases. 5. the temperature of the water increases. Freezing is a change from what phase to what phase? Which of those two phases has more energy? So, which direction is the energy flowing? 41 A projectile fired into the air suddenly explodes into several fragments. What can be said about the motion of the center of mass of the system made up of all the fragments after the explosion? 1. Center of mass of the system moves in the direction opposite to the direction of a fragment with the biggest mass, 2. Center of mass of the system moves in the direction of the biggest fragment, 3. Center of mass of the system moves in the direction of a fragment with the biggest mass, 4. There is not enough information given. 5. Center of mass does not move, 6. Center of mass of the system follows the same parabolic path the projectile would have followed if there had been no explosion, 7. Center of mass of the system moves in the direction opposite to the direction of the biggest fragment, 8. Center of mass of the system moves in the direction opposite to the direction of a projectile just before it exploded, What can be said about the temperature of a material that is going through any phase change? Consider a projectile: Its mass has a vector momentum as it flies. Even what causes the explosion is part of that momentum. So, when the explosion happens and pieces are pushed (impulse) in different directions, does the momentum of the entire projectile mass change?

14 42 (part 1 of 3) A projectile is shot on level ground with a horizontal velocity of 19 m/s and a vertical velocity of 24 m/s. Find the time the projectile is in the air. The acceleration due to gravity is 9.8 m/s 2. Answer in units of s 43 (part 2 of 3) Find the range R. Answer in units of m 44 (part 3 of 3) Let the magnitude of v 0 be the same as in part 1, but consider the angle Θ required to obtain the maximum range. Find the height attained for the maximum range. Answer in units of m 45 (part 1 of 2) An object is moving so that its kinetic energy is 98 J and the magnitude of its momentum is 21.7 kg m/s. Determine the speed of the object. Answer in units of m/s Looks like a mother/grandmother problem to me. Find the down range distance. What is the angle for best down range distance? Hint: First find v 0 before trying to find the components for this problem. Two equations (KE and momentum) with two unknowns Hmmm It looks like you will have to substitute one equation into the other 46 (part 2 of 2) Determine the mass of the object. Answer in units of kg Same equations, but you have found one variable so find the other.