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: The work done in accelerating a ball to a certain speed

  1. Sep 8, 2012 #1
    1. The problem statement, all variables and given/known data
    The fastball of a famous pitcher in the National League has
    been clocked in excess of 95 mph. Calculate the work done
    by the pitcher in accelerating the ball to that speed. The
    mass of a baseball is 0.145 kg.

    mass = 0.145 kg
    final velocity (in m/s) = 42.4688 m/s
    initial velocity = 0 m/s

    2. Relevant equations
    F = ma
    w = F*distance

    3. The attempt at a solution
    I tried setting up F = ma to find something, but the only known variable is mass. I also tried kinematics, but there are only two known variables that go into the equations and I can't isolate any variables. Is there an equation I'm forgetting, or am I just looking at this problem the wrong way? Thanks.
  2. jcsd
  3. Sep 8, 2012 #2
    How is work related to energy?
  4. Sep 8, 2012 #3
    Ohhh, work is the change in energy. So the work done would just be the kinetic energy of the ball at the velocity?
  5. Sep 8, 2012 #4
    He might very well have done some other work, but the question is specifically about work spent on accelerating the ball.
  6. Sep 8, 2012 #5
    Okay got it, thanks!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook