Hot air is lighter than cold air in Air, Winds And Cyclones – Class 7 Science Experiment
Chapter Name: Air, Winds And Cyclones
Activity Name: Hot air is lighter than cold air in Air, Winds And Cyclones
Activity Description:
In this experiment, we demonstrate that hot air is lighter than cold air by using two paper bags or empty paper cups of the same size.
These bags are hung in an inverted position on the two ends of a broomstick, which is balanced in the middle by a piece of thread. A burning candle is placed below one of the bags to observe the effects.
Required Items:
- Two paper bags or empty paper cups of the same size
- Broomstick
- Piece of thread
- Burning candle
Step by Step Procedure:
- Take two paper bags or empty paper cups of the same size.
- Take a broomstick and tie a piece of thread in the middle of the stick.
- Hang the two bags in an inverted position on the two ends of the broomstick, creating a balanced setup similar to a weighing balance.
- Hold the stick by the thread so that the bags are suspended in the air.
- Place the burning candle below one of the bags, as shown in figure (b).
- Observe what happens to the bags.
Experiment Observations:
As the burning candle heats the air below the bag, the air inside the bag gets heated. Hot air is lighter and less dense than cold air, causing the bag above the burning candle to rise, disturbing the balance of the bags.
Precautions:
- Handle the burning candle with care to avoid accidents or burns.
- Conduct the experiment in a well-ventilated area to allow proper airflow and prevent any mishaps.
Lesson Learnt from Experiment:
This experiment illustrates the principle that hot air is lighter than cold air. When air is heated, its molecules gain energy and move more rapidly, which causes the air to expand and become less dense.
As a result, the heated air rises while the cooler air sinks. This concept is fundamental in understanding various phenomena related to air movements, such as convection currents and wind patterns.
