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!

Coefficient of Restituion

  1. Feb 2, 2016 #1
    1. The problem statement, all variables and given/known data
    So we are doing a lab that is basically finding the coefficeint of restituion, what we did in this lab is drop a tennis ball from an initial height (recorded that height) and timed it until it stopped bouncing. So we have the time it stopped bouncing at and the height, and now we have to find the coefficeint of restution.

    So I am guessing the two bodies in this situation is the ball, and the floor?

    2. Relevant equations
    e = (v2final - v1final / v2initial - vinitial)

    3. The attempt at a solution
    So i know that v2f - v1f is equal to the velocity of seperation, which is the veloicty of the ball and second body after the collision, and v2i - v1i is the velocity of the ball and second body before the collision. Before i move further i would like to have help figuring out the second body in this collision.
     
  2. jcsd
  3. Feb 3, 2016 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

    The rebound speed of the Earth can be assumed zero.

    You have recorded the time to execute a number of bounces?
     
  4. Feb 4, 2016 #3
    Since the speed of the earth is zero e = -V1 / V0
    From this you can show that e = (h1 / h0)^1/2 or h1 = e^2 h0
    and h2 = e^2 h1 = e^4 h0 and hn = e^2n h0
    Now, can you use this to find and expression for tn ?
     
  5. Feb 4, 2016 #4

    NascentOxygen

    User Avatar

    Staff: Mentor

    What is tn and why do you need to determine it? You still haven't explained exactly what data you recorded; I think it would be difficult to sense precisely the moment that a ball takes its final "bounce", and it's not clear how you would use that moment.
     
  6. Feb 4, 2016 #5

    gneill

    User Avatar

    Staff: Mentor

    I suspect that the time between bounces follows a sequence that has a finite sum, and that the sum depends upon the coefficient of restitution (among other things). So if you determine a time that the ball finishes bouncing (at least perceptibly to the observer), then you can determine a value for the coefficient.
     
  7. Feb 4, 2016 #6

    NascentOxygen

    User Avatar

    Staff: Mentor

    I was inviting OP to post the maths he has on this; most likely it has been discussed in class or homework.
     
  8. Feb 4, 2016 #7

    gneill

    User Avatar

    Staff: Mentor

    Ah. Sorry about that.
     
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: Coefficient of Restituion
  1. Fresnel coefficients (Replies: 3)

  2. Coefficient of drag (Replies: 6)

  3. Frictional Coefficient (Replies: 13)

Loading...