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: Calculating velocity in regards to the mass and kinetic energy of an object

  1. Aug 10, 2012 #1
    1. The problem statement, all variables and given/known data

    How fast is a baseball with a mass of 145 g travelling if it has 94 J of kinetic energy?

    2. Relevant equations

    m = 145 g or 0.0145 kg
    Ek = 94 J
    v = ?

    v = √2Ek/m

    3. The attempt at a solution

    I get...
    v = √2(94)/0.0145 kg
    v = √12966
    v = 114

    But my book says it should be 36 m/s. What am I doing wrong?

    It also mentions that I need to recall that 1 J = 1 kg . m^2/s^2 but I am unsure how to incorporate this into the equation or if it is even necessary.
  2. jcsd
  3. Aug 10, 2012 #2
    Your mass should be .145 kg.
  4. Aug 10, 2012 #3
    Your mass should be 0.145 kg and not 0.0145kg
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook