Question

A bicycle pump is used to fill a tyre with air. When the piston is pushed, air is filled. When the piston is pulled back, why doesn't the tyre deflate?

• A. Pressure inside the tyre equals atmospheric pressure, hence air cannot leave.
• B. The valve is open allowing the free flow of air through it.
• C. The valve is closed blocking the free flow of air through it.
• D. The valve is open when piston is pushed and closed when piston is pulled.

Answer 1

The correct option is D The valve is open when piston is pushed and closed when piston is pulled.

Tyres of vehicles are fitted with special valves that allow air flow in only one direction. So, when air is forced inside the type, valve is open and when it is pulled back, it is closed hence blocking the air.