# Homework Help: Circular Motion Lab with Hanging Mass - Trying To Find Centripetal Force

1. Nov 21, 2009

### albert4united

Sorry if this is posted in the wrong area, I am relatively new.

Circular Motion Lab is set up like this to study circular motion:

Rubber stopper is secured to string .4m long, and is spun horizontally and achieves period of 0.56275s. The hanging mass is 0.03kg. The mass of the stopper is unknown.

I figured out that Centripetal velocity is 4.466m/s.

The vertical forces is Fnet = Ft - Fg

Ft= Fnet + Fg
Ft = m(a + g)
Ft= 0.03 (9.81)
Ft= 0.2943

The horizontal forces are Fc = Ft
Fc= 0.2943 N !!!!!!!!!!

Is this done RIGHT to FIND the centripetal FORCE of the rubber STOPPER?
Please explain if I am wrong...

Last edited by a moderator: May 4, 2017
2. Nov 21, 2009

### Delphi51

You must consider the angle of droop in your force diagram. Tension is certainly not a vertical force - it is PARTLY vertical and partly horizontal. You'll have sin A and cos A in your expressions when you separate T into horizontal and vertical parts.