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!

Kinematics Sprinter Question

  1. Sep 21, 2009 #1
    1. The problem statement, all variables and given/known data

    A world-class sprinter accelerates to his maximum speed in 3.8 s. He then maintains this speed for the remainder of a 100-m race, finishing with a total time of 10.4 s.

    (a) What is the runner's average acceleration during the first 3.8 s?

    (b) What is his average acceleration during the last 6.6 s?

    (c) What is his average acceleration during the entire race?

    (d) State why your answer to part (c) is not the average of the answers to parts (a) and (b).

    2. Relevant equations

    Kinematic Equations

    3. The attempt at a solution

    I know that part b is 0 because the runner maintains a constant velocity. But for parts a, c, and d, I'm not sure what to do. I know I have to find the distances he runs while his speed changes and when it is constant and then find the acceleration, but how do I do this?


    Thank you so much for your help!!
     
  2. jcsd
  3. Sep 21, 2009 #2

    rl.bhat

    User Avatar
    Homework Helper

    Assume a as acceleration and v as the maximum velocity.
    Using the kinematic equations
    Find v(max) in terms of a and t1
    Find x1 in terms of a and t1.
    In the second part the velocity is constant.
    So x2 = v(max)*t2.
    Then put x1 + x2 = 100 m, and solve for a and v(max).
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Kinematics Sprinter Question
Loading...