give me example of air exert pressure.

 conversion of woollen fibre into wool

A very easy experiment to show that air exerts pressure:

Experiment:Take a plastic bottle ( the thinnest plastic that you can find). Suck the air out of the bottle. You can do this by using a vaccum pump.

Observation: The bottle distorts in shape as the air is being sucked out the bottle.

Conclusion:The air outside the bottle exerts pressure on the bottle because of which the shape of the bottle is altered.

experiment: take a bottle fill it with approximatly half with water. Boil the water on a candle flame ,untill the water boils.then close the cap of the bottle.The water wapour inside the can condenses,leaving no space andthre is low preasure created inside the can and outside the can thereis high preasure formed.As we knowthatair always travels from high preasure area to low preasure area . Here it is the same case.As the airout the the can ishigh preasure ,the windmoves with great speed and the bottle gets compressed.THHHIS ACTIVITY SHOWS THAT AIR EXERTS PREASURE.

Take a plastic bottle. Suck the air out of the bottle. You can do this by using a vaccum pump.The bottle distorts in shape as the air is being sucked out the bottle.The air outside the bottle exerts pressure on the bottle because of which the shape of the bottle is altered.