Simple Harmonic Motion: Maximum Speed of a Grandfather Clock Pendulum in cm/s

[chess10771]

Homework Statement

A grandfather clock is constructed so that it has a simple pendulum that swings from one side to the other, a distance of 22.0 mm, in 1.00 s. What is the maximum speed of the pendulum bob? Use two different methods. First, assume SHM and use the relationship between amplitude and maximum speed.
First answer to be in cm/s

Second, use energy conservation. Assume g = 9.81 m/s2
Second answer to be in cm/s

The Attempt at a Solution

The amplitude is (22.0 mm)/ 2 = 11.0 mm and the period is 1.00 s.
1st method:
(2*pi*11*10^-3 m) / 1 s = 6.91 cm/s
6.91 isn't showing as the correct answer, wondering what i did wrong.

 

[rl.bhat]

Period is the time for one to and fro motion of the pendulum.