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## Homework Statement

You stand at rest on one end of a 3.00m long platform (also at rest). The platform is on a smooth friction-less surface. If you walk from one end of the platform to the other at the constant rate of 2.00m/s, what is the kinetic energy of the system (you and the platform) right before you reach the other end if your mass is 50kg and the mass of the platform is 100kg. What is the displacement of the platform when you reach the other end?

## Homework Equations

MuVu + MpVp = 0

## The Attempt at a Solution

Since the system is initially at rest then the momentum is 0, so by conservation of momentum when you move at 2.00m/s the platform must move in a way so that the net momentum is still 0

Mu = your mass Vu = your velocity

Mp = mass platform Vp = Velocity Platform

MuVu+ MpVp = 0

Vp = -(MuVu)/Mp

Vp = -(50kg*2.00m/s)/100kg

Vp = -1.00m/s

So your velocity is 2.00m/s and the platform velocity is -1.00m/s

How can we use this information to find the kinetic energy?

Next the displacement of the platform i just calculated the time it takes for you to get to the other side and then apply that time to velocity of the platform

3.00m/2.00m/s = 1.5s

delta x = (-1.0m/s)(1.5s)= -1.5m

Not sure if that is right but please let me know

Thanks in advance