# Homework Help: Non-Uniform Motion in a circle

1. Jul 7, 2008

### confusedalot

I am a bit confused by this question(see attached image). This has been posted before but im not any further forward. My problems are:

P1 - has this got the following forces acting on it: Weight, Tension, and Natural reaction force?

and thus does the equation of motion end up as:

mr''= -|T|er - (mgcos a)er - (mgsin a)eo + |N|er

where er and eo are the radial and tangential components respectively

Then is it a case of gathering the similar terms and resolving in the er direction to get:

ml0'^2 = mg cos a - |T|

P2 - is this just experiencing the tension of the string and its own weight?

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2. Jul 7, 2008

### Staff: Mentor

I'm not clear as to what you are asked to solve for.

3. Jul 7, 2008

### confusedalot

need to identify the forces acting on each particle using appropriate co-ordinates system and then write the equation of motions for each of particle.

4. Jul 7, 2008

### Staff: Mentor

(1) Looks like you have tension along the radial direction.
(2) Which way does the tangential component of gravity act?

I think it might be a bit clearer if you wrote the radial and tangential equations separately.

I don't know what you did here.

Right.

5. Jul 7, 2008

### tiny-tim

Welcome to PF!

Hi confusedalot ! Welcome to PF!

Hint: forget tension etc … try starting with conservation of energy.