Why do the passengers in high- altitude jet planes feel the sensation of weight while passengers in the International Space Station do not?
The sensation of weight is caused by the force of gravity acting on a mass. Passengers in high-altitude jet planes feel the sensation of weight because even though the plane is flying at a high altitude, it is still within the Earth's gravitational field. The plane and its passengers are constantly being pulled towards the center of the Earth.
On the other hand, passengers in the International Space Station (ISS) do not feel the sensation of weight because they are in a state of freefall. The ISS orbits the Earth, and as a result, it is in a constant state of falling towards the Earth but also moving sideways fast enough to continuously miss it. This creates a sensation of weightlessness as the gravitational force acting on the passengers and the station is effectively canceled out by the centrifugal force of the orbit. Therefore, passengers in the ISS experience microgravity, or the feeling of being weightless.
The passengers in high-altitude jet planes feel the sensation of weight because they are still within the Earth's atmosphere and experience the force of gravity acting on their bodies. The sensation of weight is due to the normal force that the floor of the plane exerts on them, which counters the force of gravity.
On the other hand, passengers in the International Space Station (ISS) do not feel the sensation of weight because they are in a state of freefall or microgravity. The ISS is orbiting around the Earth and constantly falling towards it, but because it is also moving horizontally fast enough, it keeps missing the Earth. This continuous freefall cancels out the effect of gravity acting on the astronauts' bodies, making them experience a feeling of weightlessness.
To understand this concept yourself, you can think of a simple experiment: drop a ball in an elevator as it moves upwards. When the elevator is going up and slows down, you will feel a momentary sensation of weightlessness as the normal force exerted by the elevator floor decreases. Similarly, when the elevator is going down and accelerates, you will feel a momentarily increased weight due to the increased normal force. These sensations occur because the elevator floor's force on your body is temporarily out of balance with the force of gravity.
In space, there is no surface to exert this normal force on the astronauts, which is why they feel weightless. But it's important to note that despite this sensation, the force of gravity is still present in space, as it is what keeps the ISS in orbit around the Earth.