Simple Harmonic Motion Pendulum problem

  • #1
bobbricks
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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

  • #2
Orodruin
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A is the amplitude of oscillation, not the length of the pendulum.
 
  • #3
bobbricks
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Is A=0.3-0.3cos10 ?
 
  • #4
bobbricks
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Bump
 
  • #5
Orodruin
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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?
 
  • #6
bobbricks
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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..?
 

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