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Homework Help: Spring suspension on car

  1. Oct 15, 2003 #1
    Ok, here is the problem:

    A 1200 kg car carrying four 82 kg people travels over a rough "washboard" dirt road with corrugations 4.0 m apart which causes the car to bounce on its spring suspension. The car bounces with maximum amplitude when its speed is 15 km/h. The car now stops, and the four people get out. By how much does the car body rise on its suspension owing to this decrease in weight?
    I know I'm supposed to find the spring constant of the suspension here and first I need to find the angular frequency...but how do I go about finding the angular frequency?

    If anyone can help as soon as possible...thanks a lot
    Last edited by a moderator: Oct 15, 2003
  2. jcsd
  3. Oct 15, 2003 #2
    ω = 2Πf

    (f you can get from the speed and the space between the bumps.)

    Does that help?
  4. Oct 15, 2003 #3
    How do you get f from the speed and the bumps?

    I must have a really bad book...but it tells me that to get the frequency I need the angular frequency.

    My book says f= w/2pi...which gives you w right back.

    Thanks for the help
  5. Oct 15, 2003 #4
    ω is the angular frequency (i.e. radians per second)

    f is the linear frequency: cycles per second, bumps per second, bumps per minute, bumps per hour...

    You have kilometers per hour and bumps per meter...

    Got it?

    Then, use
    ω = 2Πf
    to get the angular frequency.

    Then use what you know about simple harmonic motion to get the spring constant.
  6. Oct 16, 2003 #5
    Thanks a lot.
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