inside the house MP) For assigned homework and other learning materials, go to M
ID: 1864319 • Letter: I
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inside the house MP) For assigned homework and other learning materials, go to MasteringPh Conceptual Questions 1. When a block with a hole in it is heated, why doesn't the material around the hole expand into the hole and make it smaller? Explain this behavior by looking at the forces operating at the molecular level. 2. You have a drink that you want to cool off. You could put in 100 g of ice or 100 g of water, both at 0°C. Which one would be more effec- tive in cooling your drink? Why? A thermostat for controlling household heating systems often con- tains a bimetallic element consisting of two parallel strips of differ- ent metals welded together along their length. When the temperature changes, this composite strip bends one way or the other. Why? 4. Why is it sometimes possible to loosen caps on screw-top bottles by 5. To raise the temperature of an object, must you add heat to it? If you 6. Is it possible to combine ice and water in an isolated environment 12 dipping the capped bottle briefly into hot water? add heat to an object, must you raise its temperature? Explain. and end up with a final temperature for the system that is below the freezing point? If so, what do the initial conditions of the ice and water need to be in order for this to happen? 7. If you have wet hands and pick up a piece of metal that is below the freezing point of water, you may stick to it. This doesn't happen with wood. Why this difference in behavior?Explanation / Answer
1. The change in length due to temperature difference is directly proportional to its linear dimensions The dimensions of block are large compared to dimensions at close to the hole. So expansion rate is high at outer area than near the hole. So even if the hole wants to into into the hole, the outer regions will pull it due to their high expansion rate.
2. Using water at 0 c will be more effective because water has better thermal conductivity than ice. So cool drink will cool quicker in water.
3.the coefficient of thermal expansion is high for one metal and low for other metal. So both will expand at different rates. The one which will expand faster will bend into the one expanding slower. So bending takes place.
4. Due to hot water the cap will expand more and mouth will expand less, so the threads can slide off each other easily.
5.to raise the temperature of object we have to add heat to it. The heat absorbed by it will converted into internal energy. More the internal energy more the temperature raise. The other way around is not a logical statement.
6. Many combinations can achieve this out put. Take less mass of water at zero degree centigrade and more mass of ice well below zero degree centigrade. The final temperature of the system will be below freezing point of water.
7.metal is very good conductor of heat compared to wood.so when we touch metal, it will absorb heat from water very quickly and water freezes. The wood instead will absorb heat very slowly, in the mean time water again absorbs heat from our body so there is no chance to freeze.
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