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 question

  1. Mar 24, 2014 #1
    1. The problem statement, all variables and given/known data

    At international cricket games, it is commonplace to display on the scoreboard a speed for each bowl. Because the ball is subject to a drag force due to air proportional to the square of its speed given by R = kmv^2, it slows as it travels 20 m toward the wicket according to the formula v = vie^(−kx). Suppose the ball leaves the bowler's hand at 151 km/h. Ignore its vertical acceleration, and determine the speed of the ball when it hits the wicket. (For a cricket ball, assume the mass is 0.16 kg, the radius is 3.5 cm, and the terminal velocity is 40 m/s. The density of air is 1.2 kg/m3.)

    2. Relevant equations

    Apart from the equations i have tried R=0.5DpAv^2
    but i don't know the drag coefficient!

    3. The attempt at a solution
    Honestly i don't know where to start, i have tried googling a similar question also.
    The problem is I cannot figure out R. If i knew drag coefficient i could work out k, then work out v over the distance
     
  2. jcsd
  3. Mar 24, 2014 #2

    AlephZero

    User Avatar
    Science Advisor
    Homework Helper

    What is the drag force at the termimal velocity? You can work out "k" using that information.
     
  4. Mar 25, 2014 #3
    I worked drag force R out with R = -bV and using the above formal for R with a drag coefficient of .3 which i found online. Both gave a similar result. I got 133km/h
     
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: Drag question
  1. Drag question (Replies: 2)

Loading...