# Homework Help: Rotation Mechnics Problem

1. Sep 3, 2013

Hi friends,
Feeling pleasure to share some more aspects with you.
I am getting a doubts in some of the problems.

The problem is:
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Attempt,

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But the book says the answer is option (D).
Please friend help to get rid off.

Last edited by a moderator: May 6, 2017
2. Sep 3, 2013

### voko

What is the total force felt by the rod at x? Why?

3. Sep 4, 2013

I am getting the equation for the right side of 'x'.

4. Sep 4, 2013

5. Sep 4, 2013

### voko

At point x in the rod, there is some force of tension. You computed the force of inertia due to dx just next to x. But what about other parts of the rod? Which parts of the rod contribute to the tension at x: the parts further away from the axis of rotation, or closer to it?

6. Sep 4, 2013

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Last edited by a moderator: May 6, 2017
7. Sep 4, 2013

### voko

Imagine that the rod itself is massless. Now let there be some point mass attached to the rod that is closer to the axis of rotation than x. Will there be any tension at x? Then let there be a point mass further from the point of rotation than x. Will there be any tension at x?

8. Sep 4, 2013

Yes outer mass of the rod i.e. the right side part will apply tension on it.

OK let me try it first.

9. Sep 4, 2013