In which of the following cases would you feel weightless?

Question

a. while falling from a roof
b. while parachuting from an airplane (parachute open)
c. while accelerating downward in an elevator
d. while walking on the Moon

Answer 1

A. While falling from a roof



This is the only option from the above that allows for free-fall. You could feel weightless in an elevator that was in free-fall or when jumping from an airplane with your parachute closed - but those aren't options.

Answer 2

(C) The elevator. Initially, on the 100th floor, you're standing on a stationary elevator floor with gravity pulling you down the elevator shaft. You experience the feeling of weight because you're being stopped by moving by the floor. However, when the elevator pulls down, your gravity of 9.81 m/s^2 is seemingly reduced because the elevator begins to pull away from you. If you have nothing to "feel" your weight against, you won't feel your weight. You'll also have the appearance of weightlessness because you'll be traveling at the same speed as the inside of the elevator, so you'll have no visual reference to look at and tell you that you're moving.



This is exactly how astronauts train to operate in zero gravity. There's a large 737 that has been specially outfitted with just one large cabin and more powerful engines than normal. This plane, the "Vomit Comet," (no, I'm not the one who made that name up) will climb to a very high altitude, with everyone experiencing gravity, then it will quickly nose over and free-fall toward the surface. Since the astronauts inside are falling just as fast as the plane, and there is no visual cue, and not even any moving air to give any sense of motion, it feels like zero-g, or "weightlessness." I'm sure you've seen some video of them flipping around, playing with blobs of water, and so on.



So dropping elevator... dropping airplane... same thing. You "feel weightless."

Answer 3

a for sure and maybe c, if the acceleration happens to match the gravitational acceleration of the planet you are on (on Earth, that is 9.8 m/s^2 or 32.2 ft/s^2).



"Weight" is the force that keeps us from falling.



Gravity tries to pull us down with a certain acceleration. This acceleration acts on our mass because Earth's gravity is exercising a force on our mass (F = m a).



But we are not (normally) moving because the ground pushes back up on our feet with a force that is equal to that of Earth's gravity: that force is our weight.



Remove that force (for example, open the trap door on which you stand) and you are suddenly without weight. Earth's gravity will be the only force acting on you, accelerating you downwards.



This feeling (of weightlessness) does not last forever because of air resistance. The net acceleration will diminish gradually (because of the increasing force of air resistance), until you reach terminal velocity. At that point, air resistance is equal to your weight... and you feel it on any part of your body that air is pushing on.



What the parachute does is increase greatly the effect of air resistance (acting on a much larger surface) so that your maximum speed is a lot less than without the parachute.



Once the force of Earth's gravity and the force of air resistance are balanced, you are no longer accelerating (you are going down at a constant speed).



From most roofs, the air resistance is still negligible by the time you go splat, therefore you will have felt "weightless" during the fall. However, most of us are usually too distracted by the ground coming up to smack us, so we do not have time to enjoy the feeling.

Answer 4

a. while falling from a roof

And maybe c, because you'll fell weight less when the elevator is accelerating downwards, your full wight wont be on you. This was one of the though experiments of Einstein.

Answer 5

A falling off a roof

Answer 6

what a Q .. :)



so - in first 2 examples - you would feel REALLY heavy - cause the fall is caused by your weight.



number 3 makes you feel less weightless, cause reverse vector of elevator going down wouldnt subtract much from 1G that occurs on earth. you would feel 0.9 gravity - and still feeling your weight.



on the moon - gravity is 0.16 of the earth - so i guess you would feel most weightless there.

Answer 7

u can feel weightless by falling off a shed with a load of glass on the ground its weird as u fall it feels like ur going in slow motion as ur face smashs into the glass and thats why i have 4 stichs on my four head