Conservation of Momentum in Women Jumping Off Flatcar

[S0C0M988]

N women, each with mass m, stand on a railway flatcar of mass M. Tehy jump off one end of the flatcar with velocity u relative to the car. The car rolls in the opposite direction without friction.

A- What is the final velocity of the flatcar if all the women jump at the same time?

B- What is the final velocity of the flatcar if they jump off one at a time? (The answer can be left in the form of a sum of terms)

 

[radou]

Use conservation of momentum.

P.S. Why women? Is it supposed to encourage creativity?

 

[S0C0M988]

I know that it's conservation of momentum, but I don't know how to set up the starting equations or how to apply it.

 

[radou]

I know that it's conservation of momentum, but I don't know how to set up the starting equations or how to apply it.

Hint: look at the women and the platform as a system. What is the initial momentum of the system? What is the final momentum of the system? In what relation must they be?