Answer
When the air in a high-speed train is accelerated, this causes a decrease in air pressure. As a result, there will be a pressure difference on a passenger's inner ear and a passenger's outer ear. When the ear pops, it equalizes the pressure on either side of the ear.
Work Step by Step
According to the Bernoulli equation, there can be pressure differences at different altitudes but there can also be pressure differences depending on the fluid's velocity.
A fluid moving quickly has a lower pressure, while a fluid moving slowly has a higher pressure. When the air in a high-speed train is accelerated, this causes a decrease in air pressure. As a result, there will be a pressure difference on a passenger's inner ear and a passenger's outer ear. When the ear pops, it equalizes the pressure on either side of the ear.
