# Translational Motion and Center of Mass

1. Nov 8, 2009

### The_Fritz

1. The problem statement, all variables and given/known data
A 280-kg flatcar 25m long is moving with a speed of 6.0m/s along horizontal frictionless rails. A 95-kg worker starts walking from one end of the car to the other in the direction of motion, with speed 2.0m/s with respect to the car. In the time it takes for him to reach the other end,how far has the flatcar moved?

2. Relevant equations
Falls under the category of Center of Mass and Translational Motion
Ma_cm = $$\Sigma$$F_ext

3. The attempt at a solution
Since the rails are frictionless I figured the mass of both the flatcar and the worker are irrelevant.
Time it takes worker to walk to end of flatcar = (25m)(second/2.0m) = 12.5 s
Distance flatcar travels in the time it takes worker to walk to the other end =
(6.0m/s)(12.5s)=75m
Is this the correct answer or am I missing something???? Input will be very much appreciated.