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Forces (Newton's Law) Help

  1. Sep 26, 2006 #1
    Well, I am having trouble with this and I been looking at the book for a long time and still lost. The teacher never went over this so no notes to help me out here either.

    A football punter accelerates a football from rest to a speed of 10 m/s during the time in which his toe is in contact with the ball (about 0.18 s). If the football has a mass of 0.50 kg, what average force does the punter exert on the ball?
    N

    I have no slight clue on where to start or what formula I should be using. Any help would be great.
     
  2. jcsd
  3. Sep 26, 2006 #2
    I think that means the football's starting speed is 10m/s which is the time the football punter kick it!
     
  4. Sep 26, 2006 #3
    edit: okay i figure out how to do the first one but at a lost on this problem

    A freight train has a mass of 1.3 x 10^7 kg. If the locomotive can exert a constant pull of
    6.8 x 10^5 N, how long does it take to increase the speed of the train from rest to 84 km/h? min

    so far i got this part from reading the book ma = F_net --> a = F_net/m =

    6.8 x 10^5 N/1.3 x 10^7 kg = .052 m/s^2

    84km/h x .278

    I think i use v = at + V_0 = (.052)t = 23.352 t = 449 second

    edit: okay nevermind i figure this out do to my own mistake. I got the wrong conversion for km/h to m/s. I done correction to it.
     
    Last edited: Sep 26, 2006
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