# Pendulum problem

1. Apr 28, 2005

### Punchlinegirl

Indiana Jones is swinging from a rope. The distance between the pivot point and his center of mass is 31.0 m. He begins swinging from rest at an angle $$\theta$$ = 17.0 degrees. Assuming the Indiana and the rope can be treated as a simple pendulum, what is the value of $$\theta$$ after 1.33s (in degrees)?

i have no idea where to begin on this problem. I know that the formula for a period of a pendulum is $$T= 2\pi \sqrt L/g$$ , but i dont' know where the angle comes into play. Any help?

2. Apr 28, 2005

### Pyrrhus

Use the solution to the differential equation

$$\ddot{\theta} + \omega^{2} \theta = 0$$

where $\omega = \sqrt{\frac{g}{L}}$

For this case you will need:

$$\theta (t) = \theta_{max} \cos (\omega t)$$

Last edited: Apr 28, 2005
3. Apr 28, 2005

### Punchlinegirl

ok i got it.. thanks