Question

A boy sitting on a surface inside a satellite moving around the earth feels weightless because

• A. the earth does not attract the object in a satellite
• B. the reaction on the person balances the gravitational force
• C. a person sitting in the satellite is not accelerated
• D. the normal force (reaction) is zero

Hint:

Weightlessness occurs when there is no normal force acting on an object, as in free fall. In a satellite, both the satellite and the person inside it are in free fall, and hence the person feels weightless.

Answer 1

The Correct Option is D

Step 1: Understanding weightlessness in a satellite.
When a person is inside a satellite orbiting the Earth, both the satellite and the person inside it are in free fall. The satellite is constantly falling towards Earth, but it has a high horizontal velocity, so it keeps missing Earth and stays in orbit. The person inside the satellite, being inside the same frame of reference, experiences no contact force from the satellite’s surface and hence feels weightless.
Step 2: Analyze each statement.
(1) The Earth does not attract the object in a satellite: This is false. The Earth does attract the satellite and the person inside, but because both are in free fall, there is no sensation of weight.
(2) The reaction on the person balances the gravitational force: This is incorrect. The reaction force (the normal force) does not balance the gravitational force in the satellite, because the person inside is in free fall, and thus, there is no normal force acting on them.
(3) A person sitting in the satellite is not accelerated: This is misleading. The person inside the satellite is indeed accelerating with the satellite due to gravity, but they do not feel this acceleration because they are in free fall along with the satellite. This is the reason why they feel weightless.
(4) The normal force (reaction) is zero: This is true. In a satellite orbiting Earth, the person inside experiences zero normal force from the surface of the satellite because both the person and the satellite are in free fall. Since there is no normal force acting on the person, they feel weightless.
Step 3: Conclusion.
The reason a person feels weightless in a satellite is because there is no normal force acting on them. Therefore, the correct answer is (4) the normal force (reaction) is zero.