Question

Question 20

Describe an activity to demonstrate that warm air is lighter than cool air.

Answer 1

Take two paper bags of the same size and weight. Hang the two bags in an inverted position on the two ends of a wooden stick. Tie a piece of thread in the middle of the stick. Hold the stick by the thread as in a balance.

Put a burning candle below one of the bags. The balance gets disturbed, due to the bag that has the candle below it. As the warm air is lighter, it rises up, pushing the respective bag.