1. Not finding help here? Sign up for a free 30min 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!

Initial speed and springs

  1. Jun 7, 2014 #1
    In a new Olympic event athletes run as fast as they can,
    jump onto a sled, ride it down a hill and compress a
    spring as far as they possibly can. (who thinks of these
    any ways)
    a. Consider a 55.0 kg athlete that makes it to a top
    speed of 12.5 m/s before jumping onto a 15.0 kg sled. What is the athlete/sled initial speed as
    she starts down the hill?
    b. If the hill is 25.0 m long at an angle of 15.0 0 how much mechanical energy does the athlete/sled
    initially have?
    c. If the hill has a coefficient of friction of 0.125, what is the speed she reaches at the bottom of
    the hill, just before hitting the spring?
    d. Assuming the spring is located just at the bottom, and the coefficient of friction is the same as
    on the hill, how far could this athlete compress the spring if it has a coefficient of 1250 N/m?

    I am not sure how to go about this question. I know that you need acceleration for initial speed but can't figure out how to find it with the numbers given.
     
    Last edited: Jun 7, 2014
  2. jcsd
  3. Jun 7, 2014 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    You don't need an acceleration. This is just a "collision" between athlete and sled. Only in (d), you can (but do not have to) calculate an acceleration.
     
  4. Jun 7, 2014 #3
    So how do I go about doing it?
     
  5. Jun 8, 2014 #4

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    With the formulas you know for collision processes...

    After the collision with the sled both move with the same velocity. Is this an elastic or inelastic collision?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Initial speed and springs
  1. Initial Mass Function (Replies: 7)

Loading...