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: Acceleration of a runner to finish in his desired time

  1. Jun 1, 2012 #1
    1. The problem statement, all variables and given/known data

    A runner hopes to complete the 10,000 meter run in less than 30 minutes, after exactly 25 minutes there are 1900 meters to go. The runner must then accelerate at 0.22 m/s^2 for how many seconds in order to achieve the desired time?

    2. Relevant equations

    V=change in distance/change intime
    avg acceleration=change in velocity/time elapsed

    3. The attempt at a solution

    V before 25 minutes=5.4 m/s
    V after 25 minutes=6.33 m/s
    Avg. Acceleration=.24 seconds (know thats not right)
  2. jcsd
  3. Jun 1, 2012 #2
    V before 25 minutes=5.4 m/s=Correct
    Question is what is time taken
    Acceleration given.

    Now we call it u not V
    You have intial velocity 5.4 m/s, distance to cover and use SUVAT to find time needed.
  4. Jun 1, 2012 #3


    User Avatar

    Staff: Mentor

    The runner accelerates steadily at 0.22m/s over a time t seconds. Then he runs at that new speed for 300-t seconds.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook