In which of the following cases would you feel weightless?
while accelerating downward in an elevator
while falling from a roof
while walking on the Moon
while parachuting from an airplane
The correct answer and explanation is :
The correct answer is: while falling from a roof.
Explanation:
Weightlessness occurs when there is no normal force acting on the body. The sensation of weightlessness is usually associated with a free-falling state where the body is in free fall and not in contact with any solid surface. The sensation of weightlessness arises because, in such a situation, you experience free fall at the same rate as everything around you, including your surroundings. Let’s look at each case in detail:
- While accelerating downward in an elevator:
When you are in an elevator and it is accelerating downward, you still experience a normal force from the floor of the elevator, which prevents you from being in free fall. Even though you may feel lighter (because the elevator is accelerating downward), you are not weightless. The sensation of weightlessness would only occur if the elevator were to fall freely under gravity (which is unlikely in a typical elevator). However, in normal scenarios where the elevator is accelerating but not in free fall, you still experience some normal force, and therefore, you feel the weight. - While falling from a roof:
When you fall from a roof, you are in free fall, meaning you and everything around you (including the air around you and any objects) are accelerating downward at the same rate due to gravity. In this state, you would feel weightless because there is no normal force acting on you. Essentially, both you and your surroundings are in a state of free fall, and you no longer feel your body’s weight relative to the ground. This is the classic case of feeling weightless. - While walking on the Moon:
On the Moon, gravity is much weaker than on Earth—about 1/6th of Earth’s gravitational force. While you may feel lighter compared to Earth’s gravity, you would still have a normal force acting on you from the surface of the Moon. Therefore, you would not feel weightless. Instead, you would experience a reduced weight. - While parachuting from an airplane:
During the initial fall when you jump out of the airplane, you feel weightless because you are in free fall. However, once you open the parachute, the descent slows down due to air resistance, and you no longer experience free fall. At that point, you would feel the weight of your body, as the parachute slows you but doesn’t eliminate gravity completely.
Thus, the only time you feel true weightlessness out of these options is when you are falling from a roof, in a free-fall state where gravity accelerates you downward, and you don’t experience a normal force.