1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: SHM and Circular Motion Problem

  1. Jun 2, 2014 #1
    Q: During an earthquake, a skyscraper is designed to sway back and forth with simple harmonic motion with a period of 8 secs. The amplitude at the top floor of a particular earthquake is 70 cm. With respect to the simple harmonic motion of the top floor, calculate the following quantities:

    a) The radius of the circle used to represent the SHM
    b) The speed of the object moving round the circle
    c) The angular velocity
    d) The maximum speed at the top floor

    I am in particular confused about part a). Would the solving of this question require the use of circular motion equations as well, or would SHM-related equations be enough to answer this?
  2. jcsd
  3. Jun 2, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Neither - it does not require any equations at all - only geometry.

    You should not be doing these problems by trying to remember which equation goes where.
    How does a circle represent SHM?
  4. Jun 2, 2014 #3


    User Avatar
    Gold Member

    Can you express the motion of the top floor as a function of time? I think if you wrote it out, It might be more obvious what you're looking for...

    *HINT* Think unit circle...
  5. Jun 2, 2014 #4
    So would the radius of the circle be equal to the amplitude?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted