Where did 15,600 kg m/s come from?

That's the change in momentum of the mass as it goes through the 1st turnaround (for the 2nd time).

Speed on entering turnaround = -39m/s + -39m/s = -78m/s
Momentum entering turnaround = -78m/s * 100kg = -7800 kg m/s
Momentum exiting turnaround = 78m/s * 100kg = 7800 kgm/s
Change in momentum of mass through turnaround = 7800 - -7800 = 15,600 kg m/s
Change in momentum of pipe as mass turns around
= -15,600 kg m/s


Edited by kallog (06/22/10 04:46 AM)