# Speed and its centripetal force of circling object

1. Jun 18, 2005

### bigman8424

an object mass of .5kb revovles uniformly in cirlce horizontal frictionless surface. it is attached by .75 m cord to pin set in surface. if object makes 2 complete revolujtions per second, find its speed and its centripetal force

mg = m(v2/r)
gr = v2
v = sq root of gr
v = sq root of 9.8*.75
v = 2.7 m/s2

anyone wanna do me a favor, and check if i'm doing' this right,
thanks a lot..

2. Jun 18, 2005

### Andrew Mason

Gravity has nothing to do with this problem. The centripetal force is mv^2/r. All you have to do is work out what v is from:

$$v = 2\pi r/T$$ where T = .5 sec.

AM