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Homework Help: Momentum impulse physics question, HELP !

  1. Oct 27, 2013 #1
    Momentum impulse physics question, HELP ASAP plz!

    1. The problem statement, all variables and given/known data
    A 4.0-kg block slides along a frictionless surface with a constant speed of 5.0 m/s as shown. Two seconds after it
    begins sliding, a horizontal, time-dependent force is applied to the mass. The force is removed eight seconds later. The
    graph shows how the force on the block varies with time.
    • What is the magnitude of the total impulse of the force acting on the block?
    • What, approximately, is the speed of the block at t = 10 seconds?

    2. Relevant equations

    p= mv
    K.E= 1/2*m*v^2

    3. The attempt at a solution
    p= mv = 20kg*m/s
    K.E= 1/2*m*v^2 = 50 J

    I was solving this past paper and the answer is 42N but idk how to get tht :s any help wud be appreciated, thanks!
  2. jcsd
  3. Oct 27, 2013 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF;
    Please show us your working and how you have been thinking about the problem so far.
    That is the best and fastest way to get the help you need.

    You are missing an equation - ##p=\int F(t)\; dt##
    ... which is to say: the change in momentum is the area under the force-time graph.
    ... what is "specific impulse"?
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