Question

Which of the following is not true about air?

• A. It makes windmills rotate.
• B. It helps in the movement of airplanes.
• C. Air is transparent.
• D. Air has no energy.

Answer 1

The correct option is D Air has no energy.

Air is transparent and hence it allows all the light that falls on it to pass through it. Moving air is called wind and since air has mass, moving air has energy. This energy is used to rotate the windmills. The energy of wind is transferred to a windmill. The windmill is used to draw water from tube wells and to run flour mills. Windmills are also used to generate electricity.

Airplanes are able to fly because air moving under their wings is strong enough to hold them up. The engines (propellers) in an aeroplane are used to make the air under the wings move at very high speed and thus make them capable enough to hold the aeroplanes up in the air.