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Heating by Hand

Heating by Hand. Foundations 4. Questions. What is the temperature of your hands? What do you think will happen when you hold a cold object in your hands? Describe the sensation you feel when you pick up a cold snowball without mittens on. How does it make your hands feel?.

pandora-rutledge
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Heating by Hand

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  1. Heating by Hand Foundations 4

  2. Questions • What is the temperature of your hands? • What do you think will happen when you hold a cold object in your hands? • Describe the sensation you feel when you pick up a cold snowball without mittens on. • How does it make your hands feel?

  3. Activity 3: How long does it take to warm something, just by holding it? • Imagine that Ann is holding a cup containing 30 cc and Betty is holding a cup containing 90 cc of cold water. Predict what you think will happen to the temperature in each cup by drawing a line graph for each one on this grid.

  4. How did the person’s hand feel after holding the cups. Describe his/her hands. • Both hands felt cold but they were different. The one with cup 2 (more water) was colder. And the hand holding cup 1 started feeling warm again much sooner than the cup 2 hand.

  5. Which cup needed the most energy to get to 10 C? • Cup 2 needed more energy, the one with more water in it. • It took longer for cup 2 to get to 20 C and the hand holding the cup was colder than the other hand. Both of these suggest that it needed more energy. If each hand is able to transfer about the same amount of energy over a time interval, cup 2 used more.

  6. Conclusion: Describe what happened in this experiment. • The temperature goes up. The water in the cup is trying to come into thermal equilibrium with the person holding the cup. Energy flows from their hand to the cup. • This type of heat transfer is called conduction.

  7. Conduction • Occurs when energy is transferred between two materials that are actually touching each other. • Direct contact • Ex. Cooking food on an electric stove is conduction

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