Why we are not crushed

The idea

Atmospheric pressure is very large, but we are not crushed because the pressure inside our bodies equals it and balances it.

A heavy air column

The air above us presses on every part of our body. The force on a 15 cm × 15 cm area is nearly the force of gravity on a mass of 225 kg.

Why are we not crushed?

• The pressure inside our body balances it
• The air is not pressing on us
• We are too strong

Balance it

Press Next step to see both pressures.

A balanced pressure

The atmosphere presses on us with a very large force. The pressure inside our body is caused by fluids and gases moving in tissues and organs. It is equal to the atmospheric pressure and balances it.

We are not crushed because the pressure inside our body equals the atmospheric pressure and balances it.

Notes

Pressure inside the body equals atmospheric pressure, so they balance.

Check yourself

We are not crushed by the atmospheric pressure because …

The pressure inside our body is caused by the …

The force of the air column on a 15 cm × 15 cm area is nearly the force of gravity on how many kg of mass?

Answer: 225 kg

It is nearly equal to the force of gravity on 225 kg (2250 N).

Inside the body the pressure is …

• the pressure inside our body balances it — correct. Yes!
• the atmosphere has no weight. The atmospheric pressure is very large. It is balanced by the pressure inside us.
• the air does not touch us. Air presses on us from all sides. The pressure inside balances it.
• weight of our shoes. Our shoes have nothing to do with it. Fluids and gases moving inside us cause it.
• movement of fluids and gases in tissues and organs — correct. Yes!
• colour of our skin. Skin colour has no effect on pressure.
• zero. The pressure inside is not zero. It is equal to the atmospheric pressure.
• much larger than the atmospheric pressure. It is equal to the outside pressure, so they balance.
• equal to the atmospheric pressure — correct. Yes!