Tension in a pendulum

1. Mar 10, 2006

finlejb

A 1.95 kg ball is attached to the bottom end of a length of 11.0 lb (48.9 N) fishing line. The top end of the fishing line is held stationary. The ball is released from rest while the line is taut and horizontal At what angle (measured from the vertical) will the fish line break?

I've got the equation $$T = mg(3-2cos\theta)$$ but when I solve that for $$\theta$$ with T = 48.9, it says it's wrong. any thoughts?

2. Mar 10, 2006

Staff: Mentor

Show how you arrived at that equation.

3. Mar 10, 2006

Andrew Mason

What is the acceleration of the ball as it moves in this path? What does it depend on? What provides this acceleration? Hint: it is not just gravity that provides the acceleration here.

AM

4. Oct 5, 2008

hsiao

Andrew, I don't see any other source of acceleration. Explain.

5. Oct 6, 2008

Andrew Mason

The ball is falling (gravity) and it is moving in a circular arc.

AM

6. Oct 6, 2008

Staff: Mentor

The ball is attached to a fishing line.