Let’s see how you did! If you didn’t get a few of these, don’t let it stress you out – it just means you need to play with more experiments in this area. We’re all works in progress, and we have our entire lifetime to puzzle together the mysteries of the universe!
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Answers:
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1. Heat is the movement of thermal energy from one object to another.
2. Heat can only flow from a higher temperature object to a lower temperature object.
3. Convection. The heat from the hot water in the shower heats up the air in the shower. The heated air rises. As the heated air rises, it creates a convection current. Which draws air into the shower and blows the shower curtain into my legs. Many of the winds on the Earth are caused by hot air rising and cold air sinking.
4. This is conduction. The fast moving molecules of the pizza bombard my poor mouth molecules. This, in turn, creates sound energy as I scream “OUCH!”.
5. This is radiation. Humans can transfer heat by radiation. The fellow sitting next to me was giving off infra-red radiation.
6. This time it’s primarily conduction. The molecules in her little hand are vibrating quickly and causing my molecules to vibrate quicker as well. There is probably some radiation going on as well, but since our hands are touching her molecules can directly affect my molecules.
7. A light colored shirt reflects more infra-red radiation so I’ll stay cooler.
8. False.
9. The “bonds” between molecules change. They can either tighten up or loosen up depending on whether the energy is increasing or decreasing.
10. They absorb heat.
11. The sweat absorbs excess heat from the body as it evaporates and cools us off.
12. The energy that’s entering the object is being used to change the bonds between the molecules. The molecules have reached their “speed limit”. They can’t go any faster or slower without changing state.
13. Heat capacity is how much heat an object can absorb before its temperature increases.
14. The teaspoon. The smaller the amount the less heat capacity it has.
15. The cheese has a much higher heat capacity then the crust. So the cheese stays hot much longer.
16. The burger holds onto its heat longer then the fries. The burger has a higher heat capacity.
17. Water has a higher heat capacity so it cools much more slowly than air. A hot air bottle will be cool in a matter of seconds. Hot water will take many minutes to cool down.
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