Question

As an airplane rises through the atmosphere, machines cause the pressure inside the cabin to decrease. As the airplane descends toward Earth, machines cause the pressure inside the cabin to increase. Based on your observations from the Can Crush Lab, explain why these changes in pressure are necessary?

Answer 1

Pressure is a measure of force per area, so the higher the pressure, the more force you have acting on the same space. The pressure inside and outside a container spontaneously tries to reach a point where both are equal (equilibrium). If the external pressure is too great, the container will be crushed. If the internal pressure is too high, the container will explode.

The plane starts on the ground, where pressure is relatively high. As it gains altitude, atmospheric pressure decreases outside the plane. If nothing changed, the pressure inside the plane would exceed the pressure outside the plan, and the plane would explode. The opposite occurs on the way down.