Conservation of Momentum Flat cars

[JamesClarke]

Homework Statement

There are 4 railway flat cars each of mass M traveling with speed v. They're not attached but move together initially without friction. A man of mass m starts at the end and jumps onto the second car, then to the third, and then on to the fourth.When he lands on the 4th it comes to rest. ie imagine the cars moving right and he jumps against motion from the right to the left. Determine the final velocities of the other cars. The man jumps the same speed every time and take the horizontal component of his jump to be u . This u is with respect to the car he jumps from. In the question it says its the same every time. Apparently the result will not depend on u. It says "Assume that the man jumps in the same way with the same velocity each time. You can call u the horizontal component of the velocity of the man wrt to the car he jumps from. The result will not depend on u"

Homework Equations

Conservation of momentum i think

The Attempt at a Solution

Pretty stuck any help would be appreciated Do we take the whole system together and then each car separately? No idea

 

[haruspex]

Just try to write the equations for the first jump. How much momentum is added to the car he jumps from?