About Weightlessness and gravity?

Question

Weight is the gravitational force acting on an object. So if two people are in space experiencing Weightlessness could one of the guys push the other gently with one finger and he would move?

If this is wrong can you explain why.

Answer 1

There have been some good answers, but let me add a couple things.

1) Depending on whom you ask (even among physics teachers), "weight" may or may not be equal to "the force of gravity". If you step onto a scale, the reading of a scale (which many people would call your "weight") is slightly less than the force or gravity - due to the spin of the earth.

Astronauts in the space shuttle still experience a significant force from the earth's gravity. They are "weightless" in the sense that they are in free fall. I.e. a bathroom scale would read zero, but gravity is indeed pulling on them.

2) Yes you could push a person in "weightless" conditions with a small force. However, this would NOT be the same as pushing a very light object on earth (say a balloon the size of a person). The person would still have the same inertia as on earth. It would be like pushing a person suspended from a long rope

Answer 2

Basically Weight is a Force. And a force only exists if there is an interaction with another mass. Therefore without interactions forces do not exist by themselves. The Gravity field is the cause of interaction beween two masses that touch. Your body is pushed down by Gravity field and you measure this push as a force and the Earth pushes back with an equal and opposite force.
In space far removed from the strong gravity field of the Earth you basically float going nowhere. You are weight less because you are not interacting with any mass structure,hence there is no force(weight).
If two astronauts collide(come in contact by interaction) a force is borne so the astronaut would feel a weight and the opposite astronaut would feel the same weight.( Newton's 3rd law). One astronaauts will move in one direction and the other in the opposite directionafter collision.
With out a mass interacting with a substance Force does not exist. No Force is =no Weight.
Neverthe less with new discovery of relativity Forces are ficticious. What is called wight in relativity is a distortion of space time.
So weight less ness per relativity theory means no distortion of space.time.Its very confusion.
Stick with Newton's theory its easier to Understand.

Answer 3

Yes. In fact, both guys would move apart from each other with approximately the same speed if they're about the same weight. Whichever guy is heavier will move more slowly as a consequence of conservation of momentum. Anyway, it's basically the same as if you push someone on Earth, except that here your friction with the ground enables you to not be pushed back when you yourself exert a pushing force. But friction depends on normal force, which in turn generally depends on gravity; with no gravity to hold you down, the ground exerts no frictional force on you, so you are thrown back by the force you exert due to equal and opposite reactions.

Answer 4

a space ship traveling towards the moon is in free-fall, influenced only by the earth's and moon's gravity. Since it is in free fall, there is no sensation of gravity on it. In other words, you start out with enough velocity that you reach the point where the two forces of gravity and cancel, and continuing on, you start to fall towards the moon. It's only when the rockets fire that you feel some weight. I guess the question is why you think you should feel gravity when you are in a spaceship moving towards the moon in free fall? edit: Even at the distance of the moon, earth's gravity is still measurable, about 0.002 m/s²

Answer 5

it's a little disconcerting seeing the number of people giving answers that think that there is no gravity in space.
people, if you don't know, why are you making things up?

tim is the only one who got it right. there is gravity, but there is also weightlessness because the astronauts are in free-fall.

yes, you can push someone with one finger, but you would both move. you'd both go back, away from each other.

Answer 6

Mass is not changed by weightlessness. So, just a small push may not be sufficient, but once the movement starts, it will continue because friction is absent. And yes, you will also move in the opposite direction to conserve the momentum.

Answer 7

Yes, because the guy's finger exerts a force on an object which is very light or of zero weight in space, so the object will move!

Answer 8

DavidK93 was right, both would move. How much depends on the force applied and the mass of each. If the masses (inertial mass, not weight) are equal, the speeds at which they move will be equal. If one is twice as massive as the other, he'll move at half the speed of the other. Technically, both you and the earth are in free fall around the sun, and when you jump up, pushing yourself away from the earth, you also push the earth away from you (Newton's 3rd Law), but since the earth is so much more massive than you, its speed away from you is so much smaller than yours it would be extremely difficult to measure.

Answer 9

Yes, that's correct. The two guys will be pushed away from one another. It's not so much the lack of gravity as the lack of friction (because there's no gravity and hence no normal force and no friction force) that you're noticing here.

Answer 10

Dear friend i won't beat you but i will answer you
you are absolutely correct but it can be other way also as you know there is no weight concept so the guy who is pulling the other guy may not be able to move him because he can himself be pulled towards him