Question

How do you know that air exerts pressure? Give some examples.

Answer 1

• Material Required: Bottle, crumpled piece of paper
• Method: Crumple a small piece of paper into a ball of a size smaller than the mouth of an empty bottle. Hold the empty bottle on its side and place the paper ball just inside its mouth. Now try to blow on the ball to force it into the bottle.

• Observation: The paper does not move inside.
• Inference: The air pressure at the mouth of the bottle is reduced due to more speed. This forces the air out from the bottle. This prevents the crumpled paper ball to move inside.

Moving air exerts pressure, when the air blows we can see the fluttering of leaves in the tree, banners and flags.