# Conical Pendulum

1. Feb 22, 2008

### sailsinthesun

1. The problem statement, all variables and given/known data
Consider a conical pendulum with a 81.0 kg bob on a 10.0 m wire making an angle of theta= 2.00° with the vertical.

(a) Determine the horizontal and vertical components of the force exerted by the wire on the pendulum.
(b) What is the radial acceleration of the bob?

2. Relevant equations
F=ma
a=v^2/r

3. The attempt at a solution
(a)After drawing the FBD for the wire and resolving the vectors, I get the horizontal force to be Fsin(theta) and the vertical to be Fcos(theta). Fcos(th)=mg so F=mg/cos(th). Then Fsin(th)=27.7484N and Fcos(th)=794.61N.

I'm pretty sure I did these correctly, but I'm not sure how to get the second part.
(b)I calculated the radius using r=10sin(2deg). Here is where I'm lost. I know a=v^2/r, and I have r, but need to find v. Any help or hints?

2. Feb 22, 2008

### Dick

If you have the horizontal force, then you know the horizontal acceleration from F=ma. That 'a' is the same 'a' as in a=v^2/r.