# Simple Harmonic Motion Pendulum problem

## Homework Statement

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

## Homework Equations

a) v=wA
b) T=2pi*root(L/g) --possibly?

## 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?

## Answers and Replies

Orodruin
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
A is the amplitude of oscillation, not the length of the pendulum.

Is A=0.3-0.3cos10 ?

Bump

Orodruin
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
Is A=0.3-0.3cos10 ?

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?

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..?