Lesson 2 of 15
Heat moves from hot to cold
Show on a big screenA hot block touches a cold block. What happens to the two numbers?
Step 1 of 4
- Two identical (exactly alike) blocks touch. One is 80 °C. The other is 20 °C.
- Heat moves from the hot block into the cold block.
- Later: 65 °C and 35 °C. The gap gets smaller.
- At the end both read 50 °C. Now no heat moves.
The hot number falls and the cold number rises, until both match.
Here we pretend no heat escapes into the air.
The rule
Left alone, heat moves from a hotter thing to a colder thing. It stops when both temperatures are the same.
- The end number is between the two start numbers.
- Two identical blocks meet halfway between their start numbers.
Here: 80 + 20 = 100, and half of 100 is 50.
Watch out!
Cold does not move into your hand from a cold glass. Heat moves out of your hand into the glass.
Now try it. Read the two numbers. Tap the answer.
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Try the lab to finish this lesson.