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 a lack of a normal force acting on the body that counteracts its weight. The sensation of weightlessness happens when the only force acting on you is gravity, and there is no upward support force (like the ground or floor). Let’s explore the scenarios in detail:
- While accelerating downward in an elevator: If you’re in an elevator that’s accelerating downward, you’ll feel lighter, but you’re not truly weightless. The elevator is still providing an upward normal force, but it’s weaker than usual because of the downward acceleration. You would feel a sensation similar to a decrease in weight, but gravity is still acting on you.
- While falling from a roof: When you’re falling freely under the influence of gravity, both you and everything around you (including the air, your clothing, etc.) are accelerating at the same rate. In this situation, there’s no upward force acting against gravity, creating a sensation of weightlessness. You and your surroundings are in freefall, so you experience this feeling.
- While walking on the Moon: On the Moon, gravity is weaker than on Earth (about 1/6th as strong), so you would weigh less but not experience true weightlessness. You still have weight due to the Moon’s gravity, and the ground is still supporting you as you walk.
- While parachuting from an airplane: When you jump out of an airplane, there is an initial freefall phase where you might feel a sensation of weightlessness because you and your parachute are both accelerating downward at the same rate. However, once you reach terminal velocity, you are no longer accelerating, and you will experience a normal force pushing back against you as the parachute slows your descent.
Thus, falling from a roof is the situation where you would feel true weightlessness because you are in freefall, with gravity being the only force acting on you.