Homework Help: Multiple-Choice Doozie

1. Sep 29, 2008

Garen

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

2. Relevant equations

3. The attempt at a solution

The way I understood is it is by taking ma and setting it equal to mv^2/r and solving for v. With this I got answer choice number 9, sqrt(glsinTHETA). But it's wrong. Can anyone direct me in the right direction to solving this deceptively easy problem? Thanks in advance.

2. Sep 29, 2008

Hootenanny

Staff Emeritus
You're on the right lines. However, you incorrectly assume that the tension in the string is mg.

3. Sep 29, 2008

Garen

So you're saying that I set mv^2/r equal g/cosTHETA ?

4. Sep 30, 2008

Hootenanny

Staff Emeritus
No. Start by writing down two equations: one for the requirement of the sum of the forces in the vertical plane, and one for the sum of the forces in the horizontal plane. In otherwords, apply Newton's second law seperately to the vertical and radial planes.