Simple Harmonic Motion Pendulum problem

1. Oct 19, 2014

bobbricks

1. The problem statement, all variables and given/known data
A simple pendulum of length =30.0cm is released from rest from an angle of θ=10.0∘ to the vertical.
Assuming that the pendulum undergoes simple harmonic motion, find its maximum speed.

Source: https://isaacphysics.org/questions/accuracy_shm_pendulum_num
2. Relevant equations
a) v=wA
b) T=2pi*root(L/g) --possibly?

3. The attempt at a solution
A=0.3-0.3cos10
w=2pi/T
so w=root(g/L) by subbing equation a) into b).
g=9.81 and L=0.3.

so v=root(9.81/0.3)*(0.3-0.3cos10)
=0.02606... ms^(-1)

But that isn't the correct answer?

2. Oct 19, 2014

Orodruin

Staff Emeritus
A is the amplitude of oscillation, not the length of the pendulum.

3. Oct 19, 2014

bobbricks

Is A=0.3-0.3cos10 ?

4. Oct 20, 2014

bobbricks

Bump

5. Oct 20, 2014

Orodruin

Staff Emeritus
How did you come up with this number? How far away from the equilibrium is the pendulum when it is at an angle of 10 degrees?

6. Nov 9, 2014

bobbricks

Its maximum velocity will be at the lowest point. The total length is 0.3m. Its current vertical height distance from the top is 0.3cos10. So the difference is 0.3-0.3cos10 which is the maximum amplitude..?