Question

Newton's third law of motion states that in every action there is an equal or opposite reaction.

But why is it when i punch a cloth that is hanging on a rope I don't feel the force that I exerted to the cloth. But when i punch the wall I can feel the force that I exerted coming back to me.

Answer 1

It is not that the cloth doesn't exert a force on you. It does push you back with an equal force. But cloth is made of a soft material so you can't feel it exerting a force on you. Whereas the wall is made up of cement and bricks. So you can easily fell the wall exerting a force on you.

Answer 2

Interesting question, could it have to do with Newton's Law of inertia? Because of the mass of the cloth it is more easily moved and the mass of the wall (obviously being much greater) will not move?

Answer 3

But that doesn't relate to why you get pain when you punch the wall, right?

Answer 4

ohhh, I guess escolas made it clearer

Answer 5

But that doesn't exactly explain the force, I think what's happening is the force is not coming directly back towards you because of the rope. It's absorbed and the direction is changed due to gravity, and the rope. And if you picture punching a piece of cloth, I think the part that you don't punch, around your hand, will come back in your direction a little bit maybe too.

Answer 6

http://www.youtube.com/watch?v=zN6kCa6xi9k could someone make this video clearer to me? Because I don't understand it that much

Answer 7

elasticity absorbs parts of the force, something like cement has no elasticity and thereby absorbs non of the force and redirects it all. A piece of cloth however, absorbs a fraction of the force redirecting only a fraction. escolas and pratu are both bringing good points to the table as well.

Answer 8

what don't you understand about that video exactly?

Answer 9

There's the answer. Thanks agreene, I really didn't know how to answer that completely accurately

Answer 10

If the Earth is pulls the moon, why is that the moon is moving away from Earth?

Answer 11

I agree with agreene

Answer 12

also this http://www.youtube.com/watch?v=d57C2drB_wc
how does the Earth's surface curves away from the astronauts?

Answer 13

Well, there are a few things you need to grasp on that one... mostly because it's a complex problem.

1. The earth and the moon are both constantly "falling."
2. They are both rotating.
3. The moon rotates slower than the earth, in fact the moon is slowing down in rotation.
4. The moon causes tides on the earth.
5. There is more mass in the earth where the plane of the moons orbit intersects the earth.
6. While the moons spin is slowing down, its orbit time is decreasing.

Basically what is happening is that the moon is exerting a specific amount of force on the earth which causes it to slow down, while causing the earth to speed up. At the same time, they are both caught in centripetal force from orbiting the sun, and the added forces from moving around the earth causes the moon to want to slide away, which it is doing.