- #1

FredericChopin

- 101

- 0

## Homework Statement

http://imgur.com/SE50jeP

## Homework Equations

F

_{net}= m*a

F

_{G}= m*g

## The Attempt at a Solution

I'm so confused about this problem and I still can't solve it after weeks.

The initial distance of the workers is irrelevant. If I treat the workers and the platform as a single system, then I don't have to worry about normal forces because they are internal forces. On my force body diagram, I have the tension force on the workers and platform due to the rope, f (two of them), and the weight force of the workers and the platform (together) as the external forces acting on the system:

(m + m + 0.5*m)*a = 2*f - (m + m + 0.5*m)*g

So the acceleration of the workers and the platform should be:

a = (2*f - (m + m + 0.5*m)*g)/(m + m + 0.5*m)

But the question doesn't allow you to enter "g", which suggests that the workers and the platform's weight is irrelevant. I don't understand why though. And what am I doing wrong? This is so frustrating. I have been trying to figure this problem out for weeks.

Thank you.