My free body diagram is correct or not?
If yes:
There is no upward force that opposite the W, the particle will fall and make an angle, [LaTeX Error: Can't write to directory] between the string and the horizontal, then it will be lifted upward until the string is horizontal by the vertical component of the T, and the process will repeat.
Am I right?

If no:
Can you correct my free body diagram please?

Attached Images

	untitled.bmp (107.2 KB, 22 views)
	untitled1.bmp (85.0 KB, 15 views)

__________________
[LaTeX Error: Can't write to directory] is a beautiful island.
Coming here for a [LaTeX Error: Can't write to directory] is a wonderful decision.
(My grammar is not good, if there is any mistake, send a private message to correct me. Thanks.)

I study in Malaysia Science University(USM) now.
Electrical Engineering

Centripetal acceleration, not being a force, does not properly belong on a FBD. Also, the centripetal force, being a net force, should not go on it either. (Though consult with your instructor, different professors have different conventions.) Otherwise your FBD and brief analysis are correct.

-Dan

__________________
"I must not fear. Fear is the mind killer. Fear is the little death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain." - The Litany Against Fear, "Dune" by Frank Herbert

What is FBD?
I don't like to ask them, they always "tangent" to the question, just touch the surface.

__________________
[LaTeX Error: Can't write to directory] is a beautiful island.
Coming here for a [LaTeX Error: Can't write to directory] is a wonderful decision.
(My grammar is not good, if there is any mistake, send a private message to correct me. Thanks.)

I study in Malaysia Science University(USM) now.
Electrical Engineering

Sorry about that. "FBD = Free Body Diagram."

-Dan

__________________
"I must not fear. Fear is the mind killer. Fear is the little death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain." - The Litany Against Fear, "Dune" by Frank Herbert

But centripetal force in this case is represented by T, the tension in the string and tension is a legitimate force isn't it?

So would the correct diagram just have W going down (which I'm guessing is gravity) and T going towards the centre of the circle?

The diagram should be correct with only weight and tension.
For tension as legitimate force, I guess it is.

For the mass at the rightmost extension of its position along the arc then this diagram is correct. However, note that as the mass falls the weight has a component in the radial direction. So the tension and weight both contribute to the centripetal force. This has the effect of increasing the tension until the mass is at its lowest point in its path.

-Dan

__________________
"I must not fear. Fear is the mind killer. Fear is the little death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain." - The Litany Against Fear, "Dune" by Frank Herbert