Vibration Question

  • Thread starter FChebli
  • Start date
  • #1
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Homework Statement

:[/B]

BoB released from rest, L = 102 cm, theta = +-5 degrees, g = 9.81 m/s2
assume a SHM
(I) Determine the angle theta after 1.6 s
(II) Determine the magnitudes of velocity & acceleration of the BoB at 1.6 s

Homework Equations



theta = A sin (w t + phai)

The Attempt at a Solution



Does phai represent the period? And how do I get it?
Do I derive theta once & twice? And why?
How do I get w & A?

Thank you!
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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Welcome to PF!

Hi FChebli! Welcome to PF! :smile:

(have a theta: θ and a phi: φ and an omega: ω :wink:)

θ = A sin(ωt + φ)

A is the maximum value (θ varies between ±A), which you can find from the question

ω is the frequency … to find the period, you need the value of t which makes (ωt + φ) increase by 2π

φ is the phase … it's often zero, but not always … you find it by putting t = 0, and seeing what θ is (or dθ/dt, if that's given instead) :wink:
 
  • #3
17
0
Thank you so much! :)
 

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