Trolley A carrying mass 10kg is moving at speed 5m/s, and collides with stationary Trolley B carrying a mass 5kg. Indicating which Law you would apply, what is the speed and direction of Trolley B if Trolley A's resulting movement is 2m/s to the left?

By the Law of Conservation of Momentum, Initial Momentum=Final Momentum, in a closed system.

Take movement to the right as + and to the left as -

Therefore equate the two as such: Initial (A+B) = final (A+B)

A+B = A+B

(+5x10) + (5x0) = (-2x10) + (5 x Y)

Y indicates speed of B

50+0=-20+5Y

70=5Y

Y=70/5

Y=+14m/s

Therefore Trolley B moves to the right at a speed of 14m/s