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!

Drag force/difficult integral.

  1. Sep 3, 2008 #1
    1. The problem statement, all variables and given/known data
    If a ping pong ball is released from rest, how long does it take for the ping pong ball to reach 90% of its terminal velocity?

    m=2.2g, density(air)=a.29kg/m^3, Cw=.5, diameter=.38mm


    2. Relevant equations
    Fd=1/2*C[tex]_{w}[/tex]+[tex]\rho[/tex]*A*v^2

    newton's second law



    3. The attempt at a solution

    I set up newtons second law for the going down case. I wanted to get v in terms of t.
    I can't solve the integral though.

    Fd-mg=m*dv/dt

    [tex]\int \frac{dt}{m}[/tex]=[tex]\int \frac{2*dv}{C_{w}*\rho*A*v^2-mg}[/tex]

    Please help.
     
  2. jcsd
  3. Sep 4, 2008 #2

    CompuChip

    User Avatar
    Science Advisor
    Homework Helper

    Maybe you can use
    [tex]\frac{\mathrm d}{\mathrm dx} \operatorname{arctanh}(x) = \frac{1}{1 - x^2}[/tex]
     
  4. Sep 4, 2008 #3
    yeah, i was able to get it to that form and it worked. Thanks.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Drag force/difficult integral.
  1. Drag Force (Replies: 4)

  2. Difficult integration (Replies: 4)

  3. Difficult Integral? (Replies: 4)

  4. Calculate drag force (Replies: 1)

Loading...