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Pysics 11 problem. help please?

  1. Dec 20, 2006 #1
    1. The problem statement, all variables and given/known data

    Pam has a mass of 40.0kg and she is at rest on a smooth level frictionless ice. pam straps on a rocket pack. the rocket pack supplies a constant force for 22.0m and pam acquires a speed of 62.0m/s

    a)what is the magnitude of the force?
    b)what is pams final kinetic energy

    2. Relevant equations

    a)F=mg
    b)Ek=1/2mv^2



    3. The attempt at a solution

    a)
    m=40.0kg
    d=22.0m
    v=62.0m/s
    F=mg
    F=(40.0)(9.8)
    F=392N

    b)
    m=40.0
    v=62.0
    Ek=?
    Ek=1/2mv^2
    Ek=1/2(40.0)(62.0^2)
    Ek=7.69x10^4J
     
  2. jcsd
  3. Dec 20, 2006 #2

    cristo

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    This is not the force you were asked for: this is the weight of the person. Try using the relevant kinematic equation to calculate the acceleration, then use newtons 2nd law to work out the force.
    This looks fine
     
  4. Dec 20, 2006 #3
    how do i figure out the acceleration without the force?
     
  5. Dec 20, 2006 #4
    wow i definately did not do this right, i got 3480
     
  6. Dec 20, 2006 #5

    cristo

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    Using the kinematic equations [hint: the relevant one to use here is v2=u2+2as, where here v is the final velocity, u is the initial velocity, a is acceleration and s is the distance.]
     
  7. Dec 20, 2006 #6

    cristo

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    I get 3495N
     
  8. Dec 20, 2006 #7
    i got 3520
     
  9. Dec 20, 2006 #8
    ok so if you put it into sig figs you would get 3.5x10^3
     
  10. Dec 20, 2006 #9

    cristo

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    Yes, if you're using 2sf.
     
  11. Dec 20, 2006 #10
    ok so thats right then?
     
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