# FBD of centripetal acceleration

1. Oct 19, 2011

### loopsnhoops

1. The problem statement, all variables and given/known data

I need to make a free body diagram of an object being twirled around on a string in a circular motion. What forces are acting on it and what are there equations? For example I know that the force of gravity is acting on the string so I am showing the Fg = mg equation on my FBD. I need to know the equation for the tension or centripetal force? Is it T = mv^2/r?

Edit: Are the forces balanced when it is moving?

2. Oct 19, 2011

### loopsnhoops

Edit 2: What does my teacher mean when he says he wants me to find the acceleration due to gravity? Does it mean find the centripetal acceleration?

3. Oct 19, 2011

### PeterO

I trust it was a typo when you said the "force of gravity on the string". Sure gravity will act on the string, but you were after forces on the object.

The forces acting are Gravity and Tension.

Is this object being twirled in a vertical or horizontal circle?

4. Oct 19, 2011

### loopsnhoops

horizontal and it was a typo

5. Oct 19, 2011

### PeterO

The only two forces acting are the field force [gravity] and the contact force [string, by tension]. Those two add [as vectors] to yield the net force - the centripetal force, which will be horizontal.