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:
Correct Answer: B. While falling from a roof
Explanation (300+ words):
The sensation of weightlessness occurs when there is no support force acting on your body. In everyday life, your sense of weight comes from the normal force — the force that the ground (or a chair, bed, or floor) exerts upward on your body. When that support force disappears, you experience weightlessness.
Let’s evaluate each option:
A. While accelerating downward in an elevator:
You might feel lighter, especially if the elevator accelerates downward, because the support force is reduced. However, you are not truly weightless unless the elevator is in free fall (which would mean the cable snapped). As long as the elevator is being controlled and hasn’t reached free fall, you’re still in contact with the floor and thus still experience a support force.
B. While falling from a roof (Correct Answer):
When you fall freely under gravity alone, you are in free fall. In this case, you are accelerating downward at the same rate as gravity (9.8 m/s²). There is no support force acting on your body, so you feel weightless. This is the same sensation astronauts feel in orbit — they are in continuous free fall around Earth. Your body isn’t pressing against anything to feel your weight, creating that sensation of weightlessness.
C. While walking on the Moon:
Gravity on the Moon is about 1/6th that of Earth, so you feel lighter, but you still have weight. Your feet press against the lunar surface, and there’s a normal force pushing up. Thus, you are not weightless; you just weigh less.
D. While parachuting from an airplane:
Although you are falling, the parachute and air resistance create an upward force balancing gravity. This means you’re not in free fall. You feel your weight as the air pushes up on you through the parachute.
Conclusion:
You feel weightless only when there is no support force — such as when you are in free fall, like falling from a roof.