Try rubbing your hands together very quickly,
they should start to feel warm. If they do you have turned some of the
movement energy of your hands into heat energy!
After a while your hands cool down but this heat
energy has not disappeared it has just moved out of your hands and spread out so
far you cant feel it anymore.
WHY IS HEAT SO SPECIAL AND
HOW CAN IT MAKE A CAR MOVE?
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The
hot air balloon rises when a fire is used to heat up the air inside the
balloon. When the fire is turned off the hot air escapes and the balloon
drops back down towards the earth. Why does the balloon take of when it
contains hot air?
When a gas such as air gets hot it takes up more
space than it did when it was cold. So the hot air inside the balloon is
more spread out than the cold air outside the balloon.
As the hot air inside the balloon takes up more
space than the cold air outside the balloon we cant fit as much air in.
If there is less air inside the balloon it must
not be as heavy as the air outside the balloon and the balloon will float
upwards just like a bubble that floats towards the top of the water.
When the fire is turned off and the air inside
the balloon reaches the same temperature as the air outside the balloon it will
drop back down because of its own weight and the people inside.
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Well we have made a balloon move and that's a
good start but we still don't know how to use this heat energy to turn a cars
wheels.
Let us use what we have learnt so far to figure
it out
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Energy exists in many forms, some we can
sense and some we cant.
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We can release the energy from a fuel if we
burn it.
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Hot air takes up more space than cold air.
PRESS THE HEAT ENGINE BUTTON TO FIND OUT
MORE
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