# Circular motion lab problem

1. Oct 28, 2012

### corollary

1. The problem statement, all variables and given/known data
For a conical pendulum:

Construct a free-body diagram for the pendulum and derive an expression for the acceleration in terms of the gravitational field strength g, the length L of the pendulum, the radius r of the circular path of the pendulum, and the frequency f of oscillation. (Hint - first derive an expression for tanθ the angle between the string and the vertical.)

2. Relevant equations
a=v^2/r
a=Δv/Δt
a=ƩF/m

3. The attempt at a solution
Have done free body diagram, can't figure out how to make equation.

Last edited: Oct 28, 2012
2. Oct 28, 2012

### haruspex

There is a specific format you are supposed to use on this forum.
What do you have for the forces - just describe them, don't worry about a diagram.
What do you have for the acceleration?

3. Oct 28, 2012

### corollary

Thank you for replying; didn't see I had to use that form.
As for forces there is the force of gravity on the pendulum mass (downwards), and the tension in the string.
As for the acceleration - I have no numerical value for it. The question needs no actual values - just variables to make the equation (a in terms of g, L, r, and f).

4. Oct 28, 2012

### haruspex

True, but you do know the direction the acceleration has to be in. So in what directions would you resolve the forces, and what equations result?