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Hot Air or Cold: Which Is Heavier?

Hot Air or Cold: Which Is Heavier? In this experiment you will learn about air motion,  how Hot air rises and you will get answer why cold air is much heavier than warm air.


  • Wooden roller.
  • Thread.
  • Empty can
  • Empty baby bottle
  • Candle


Balance an “empty” baby bottle on one end of your yardstick and a tin can on the other. Put sand or rice in the can if needed. Hold a candle flame for one minute near the mouth of the bottle. Remove the flame and balance the scale again.


The bottle goes up when heat is applied to the air in it.  You must remove sand or rice from the can on the other end to balance the scale.


Warm air weighs less than cold air occupying the same space.

This Experiment answered these questions.

  • Why does hot air go up and cold ?
  • Cold air is dense?
  • what is heavier hot air or cold air?
  • Why is cold air more dense than warm air?
  • Which is more dense hot or cold air?
  • Why Does Hot Air Rise and Cold Air Fall ?
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