A rubber ball - Internal shock question

chat · 2003-10-23 04:39:46

Please feel free to post why this won't work...

I you were to stand inside a spaceship at the front of the spaceship with your back placed firmly against the wall.
Facing towards the back you throw a rubber ball as hard as you can.
Then you would get a backward velocity until the ball hits the back of the spacecrafts wall.?

As the ball bounces of the back wall it looses some of its energy on the end wall you threw it at, but the bulk of the energy returns in the elasticity of the ball?

When the ball bounces of the end wall and you catch it and stop it from where you originally threw it , then it will also push you backwards.
Whatever energy you put into throwing the ball will be the net thrust minus air friction inside the spacecraft.

Euler · 2003-10-23 04:57:22

When the ball bounces off the back of the spacecraft, it pushes the whole spacecraft backwards. This cancels out the gain in momentum from throwing and catching the ball.

chat · 2003-10-23 05:15:40

What happens if we trow the ball and don't hits the end wall?.

Do the same thing when throwing the ball.
But this time throw the ball directly into a tube that returns to you round a corner without hitting the back wall.

You thow the ball.
It goes down a tube bolted to the wall inside the spacecraft.
The ball Never hits the end wall.
It goes round the corner of the tube near the end of the spacecraft.
And returns to you where you catch and stop it.

We loose some energy on the return corner but the ball never stops until you catch it.

Now we should have thrust without conservation of momentum being a factor?

Byron · 2003-10-23 06:54:08

Now we should have thrust without conservation of momentum being a factor?

That doesn't make sense to me at all...besides, when you finally catch the ball again, the energy expended in capturing it (minus the friction of the ball in its course around the tube) will precisely equal the energy in pushing it in the first place.

Believe me, I've been down this route of the "perpetual motion" machine before (back when I was a kid)...as nice as it sounds, it just ain't gonna happen...

B

chat · 2003-10-23 09:29:14

[color=#000000:post_uid0]A good point Byron.

But since the ball returns to us with most of its energy we get a backwards force each time we throw it and catch it.
And of course a slight sideways motion as the ball goes around the curve of the tube.

Both actions throwing and catching the ball push you backwards along with the spaceship?

Bear with me for keeping this rubber ball example, but i do have a very good idea in mind.

Not looking for perpetual motion, just motion

minus the friction of the ball in its course around the tube[/color:post_uid0]

The universe isn't being pushed apart faster.
It is being pulled faster towards the clumpy edge.

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#1 2003-10-23 04:39:46

Re: A rubber ball - Internal shock question

#2 2003-10-23 04:57:22

Re: A rubber ball - Internal shock question

#3 2003-10-23 05:15:40

Re: A rubber ball - Internal shock question

#4 2003-10-23 06:54:08

Re: A rubber ball - Internal shock question

#5 2003-10-23 09:29:14

Re: A rubber ball - Internal shock question

#6 2003-10-23 12:13:00

Re: A rubber ball - Internal shock question

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