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Homework Help: Bullet question

  1. Apr 14, 2009 #1
    1. The problem statement, all variables and given/known data
    A bullet of mass 0.010 kg and speed of 100 m/s is brought to rest in a wooden block after penetrating a distance of 0.10 m. This process takes 0.02 seconds. Theblock remains stationary during this process.

    a. what is the magnitude of the impulse delivered to the bullet by the block during this time?

    b. How much work was done ont he bullet during this process?

    2. Relevant equations
    thats what im wondering

    3. The attempt at a solution
    i cant find the formula to try it, i am pretty much just looking for the formula and what each thing stand for etc. Thanks
  2. jcsd
  3. Apr 14, 2009 #2
    Try using Ft=Δ(mv)
  4. Apr 14, 2009 #3
    sorry sounds dumb but what does F,t, delta, and mv stand for?
  5. Apr 14, 2009 #4
    no thats a perfectly decent question!! if you have never come across this equation you cant be expected to know what it means!!
    F= force
    t= time
    delta= change in
    m= mass
    v= velocity
    just a note, the product Ft is known as impulse =]
  6. Apr 14, 2009 #5
    ok so i have the change in velocity, and time, but the problem says nothing about the change of mass. and dont have the force so im assuming theres a seperate formula involving how much the bullet penetrated that will give me the force or change of mass but im thinking force. Anyone know what formula i hsould use or where i go from here? thanks
  7. Apr 14, 2009 #6
    note that Ft=Δ(mv)
    mv is just the bullet's momentum, for the momentum to change you dont necessarily have to change the mass
  8. Apr 14, 2009 #7
    whats the unit measure for impulse??? Btw it all makes sense now. Thanks
  9. Apr 14, 2009 #8
    Ns or kgms^-1
    what was the answer then?? just to check if i got it right as well =]
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