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: Find the acceleration, velocity and position

  1. Feb 8, 2009 #1
    1. The problem statement, all variables and given/known data
    The motion of a sprinter with
    mass = 80 Kg
    the sprinter is accelerated with a constant horizontal force: 400 N
    The air resistance is 0.5*p*Cd*A*(v-w)**2
    p = 1.293 kg/m**3
    Cd = 1.2
    A = 0.45 m**2
    v = velocity
    w = 0 m/s

    find the acceleration, velocity and position

    3. The attempt at a solution
    a1 = 400N/80kg

    a(t) = a1*t - (1/m)*0.5*p*Cd*A*(v)**2

    Can someone help me with the v?
    I am allowed to solve it numerically
  2. jcsd
  3. Feb 9, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    What is the a1*t term supposed to represent?

    I think this one can only be solved numerically. What have you been taught so far about that? There are many different ways to solve it numerically, it would be good if you can tell us what your professor or textbook says about this.
  4. Feb 9, 2009 #3
    Solved, I will post my solution later.
  5. Feb 11, 2009 #4
    Use initial acceleration condition and differential equations to solve the problem you geta logarithimic function of velocity with time..now again use same to get position as a function of time .
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook