Originally Posted By: paul
finaly.

Yes, finally I wrote it in enough different ways that you understood one of them. But we're not going to make any progress until you actually know what "acceleration" and "velocity" mean. Without knowing what acceleration is you can't use F=ma. Without knowing what velocity is you can't use p=mv or find a from the rate of change of v. This is why you're getting wrong results.

Quote:

the pipe can apply a force of 8000N to another object.


No. This is a 3rd misunderstanding (after v and a) that you need to solve before you can understand the system.

The force used to accelerate something doesn't determine the force it can apply to something else.

Eg: Accelerate a truck to 60mph in 20s then either:

A) Shift into neutral and let it coast to a stop.
B) Crash it into a cliff.

Do both cases apply the same force to the environment?


Extra question:

Change the 20s to 2 hours. Does that change the force in A or B?

Last edited by kallog; 09/25/11 02:27 AM.