Temperature and Heat Energy Worksheet. Answer Key Bryan/Science-8
1. In terms of thermal energy, why does a bottle of soda left in the sun have a higher temperature than one left in an ice chest? The bottle of soda absorbs radiant energy from the sun which increases the kinetic energy of its molecules. This causes an increase in its average kinetic energy and therefore and increase in its temperature.
2. Which has more thermal energy, a 5-kg bowling all that has been resting on a hot driveway for 4 hours on a 350C day, or the same bowling ball rolling down a lane in an air-conditioned bowling alley? Explain. The bowling ball on the driveway has more thermal energy. It has been absorbing the radiant energy from the sun during those four hours.
3. Why does your hand feel cool if you spill some alcohol on it? The alcohol needs energy to evaporate (change of state from liquid to a gas). It takes away heat from your hand and uses that energy to evaporate. Your hand looses heat energy and therefore feels cooler.
4. Explain why poor conductors of heat are good insulators of heat. Poor conductors of heat will not take heat away from an object quickly, therefore becoming a good insulator.
5. Why do many cooking pots and pans have wooden or plastic handles? Wood and plastic are poor conductors of heat so they will not transfer the heat from the hot pot to your hand.
6. For many years, many fast food restaurants served their hot sandwiches in plastic foam containers instead of wrapping them in less expensive paper. Why was plastic foam used? The plastic foam has many air spaces. Air is a good insulator, so the foam ends up being a better insulator and therefore allowing the sandwich to keep warmer for a longer period of time.
7. Why is winter clothing generally darker in color than summer clothing? Darker colors are better absorbers of radiant energy from the sun, so they will help you to get warmer when the temperature is low.
8. Explain why wearing two or three layers of clothing helps to keep you warmer in cold weather than does one thick layer. Air is trapped between the layers of clothing. Air is a good insulator and therefore helps to prevent your body from loosing heat.
9. Explain why the inside of an automobile left sitting in direct sunlight for several hours becomes very warm. The heat (usually from radiation) enters the car through the window and sometimes gets trapped inside because it keeps reflecting off the glass windows.
10. Explain why the rug on your floor feels warmer than the tile in the same room. The rug is an insulator and the tiles are conductors. The tiles conduct heat away from your foot therefore making you fell colder. The rug does not conduct the heat away as quickly so your foot does not feel as cold.