# Centripetal force ball on a string lab

1. Nov 17, 2016

### Revengeance

1. The problem statement, all variables and given/known data
So referring to this lab , http://static3.mbtfiles.co.uk/media...ureate/physics/824297/html/images/image12.png

In this lab you are holding the plastic tube and twirling it to make the small mass spin in a circle. Keep in mind there is a mass on the bottom.

I have to create an expression for Fc with theta and radius.

2. Relevant equations

Fc = 4pi^2rf^2 * m
3. The attempt at a solution
Well from the FBD of the small mass, we know that FC = FT

and from the FBD of the mass at the bottom we know that FT=FG.

Therefore for the system, wouldn't FC = FG of the mass on the bottom?

As for the equation i am not really sure were to start, could someone help me out please.

2. Nov 17, 2016

### andrevdh

The string attached tot the mass going in a circle is angled downwards a bit, that is the horizontal plane in which the mass is circling is a bit below the top of the tube. That is the theta that is mentioned. Best to draw a diagram and post it.

3. Nov 17, 2016

### Revengeance

so i know the lab looks something like this, and the Fg of the small mass will cancel out the fty in the tension, therefore ftx controlling the motion.

#### Attached Files:

• ###### lab.png
File size:
37.6 KB
Views:
37
4. Nov 17, 2016

### andrevdh

Yes, the x component provides the centripetal force.