Simple Pendulums: Calculating Time to Attain Greatest Speed

[alyse!!]

Homework Statement

A simple pendulum is made from a 0.67 m long string and a small ball attached to its free end. The ball is pulled to one side through a small angle and then released from rest. After the ball is released, how much time elapses before it attains its greatest speed?

Homework Equations

f=frequency
f=(1/2pi)(g/L)^.5

f=1/T
where T=period

The Attempt at a Solution

f=1/T

f=(1/2pi)((9.8m/s^2)/0.67m))^.5
f=6.007

f=1/T
6.007=1/T
T=1/6.007
T=.166s

This is the answer that i got but it is wrong and i do not know why, and now how to do it if this is the wrong way.

 

[Doc Al]

f=(1/2pi)((9.8m/s^2)/0.67m))^.5
f=6.007

Redo this calculation.

 

[jix]

Redo the calculation, perhaps, and divide period by 4, since reaching the bottom takes one-quarter of the period.