Quote:

1) -2 is a measure of the momentum added to the pipe. We can call it -2Ns

4) ... so it must maintain zero momentum all the time.

5) After the 1st acceleration the mass has momentum of -1Ns and the pipe has +1Ns


1)
Quote:

-2 was what you wanted to use instead of actual momentum.

Let's change 1) to:
1) The numbers (ignoring their values for now) represent the momentum added to the pipe. We can use the units Ns

4)
Quote:

the pipe cant maintain zero momentum because the
mass is being accelerated inside the pipe

Correct, but we don't need to enforce zero momentum on the pipe, only on the complete system. That means the sum of the momentum of every part (mass and pipe) must equal zero.

Do you agree with 4 now after this clarification?


5) Why not? What values would you use?

Last edited by kallog; 09/07/11 08:36 PM.