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Homework Help: Finding Ek with force, mass, and time.

  1. Apr 6, 2010 #1
    1. The problem statement, all variables and given/known data

    A 10kg box at rest is being pushed on a frictionless surface by a force of 10N. The force is in the same direction as the motion of the box. 10 seconds later, how much kinetic energy will this box have?

    2. Relevant equations

    1. F=ma
    2. Vf=Vi+at
    3. Ek=0.5mv2

    3. The attempt at a solution

    I used formula 1 along with the F and mass to find the acceleration to be 1 m/s2. Then, I plugged that into formula 2, given an initial velocity of 0, acceleration of 1 m/s2, and a time of 10s. This gave me Vf at 10m/s. I used that in formula 3, with mass being 10kg. This gave me a final Ek of 500J.

    Is this correct? 500J seems a little high but, I've no clue how else to do this. Thanks in advance.
  2. jcsd
  3. Apr 6, 2010 #2
    1J is the energy exerted by a force of 1N thaat moves an object by 1m. The force in this case is 10N and the distance is 50m(0.5at^2=100/2), so 500J seems fine.
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