# Centripetal force in pendulum

1. Nov 25, 2006

### duoheer

How do you calculate the centripetal force in pendulums?
THx

2. Nov 25, 2006

Draw a free body diagram first. Its always a good start.

3. Nov 25, 2006

### nrqed

You use $F_c = m {v^2 \over R}$ where R is the radius of the circle which is the length of the pendulum. You have to be given the speed or to find it using conservation of energy.

Patrick