- #1

- 28

- 0

## Homework Statement

The problem, basically, is very simple but, it is confusing me. It says:

"There is block on a moving train, which is being pushed by a man. The man applies force [itex]F[/itex] to displace the block by [itex]s[/itex]

**. The moves [itex]S[/itex] in that period. Find work done on the block by the force**

__wrt Train__**.**

__wrt ground__## Homework Equations

[itex]W=F.s[/itex]

## The Attempt at a Solution

What did is this:

The displacement of the block caused by the

*force*is [itex]s[/itex]. Hence, answer is [itex]F.s[/itex].

But, the book is including the displacement of train as well. It says that from ground, we see the block displaced by[itex]s+S[/itex]. So, answer is [itex]F.(s+S)[/itex]. There is also a note saying that this illustrates that work is never absolute.

I think that my answer is correct because displacement [itex]S[/itex] is not caused by the force and so, we should not consider that.

Please help me.