1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Momentum of a Bullet Contacting a Block

  1. Oct 25, 2011 #1
    1. The problem statement, all variables and given/known data
    A bullet with a mass of 4.0 g and a speed of 650 m/s is fired at a block of wood with a mass of 0.095 kg. The block rests on a frictionless surface, and is thin enough that the bullet passes completely through it. Immediately after the bullet exits the block, the speed of the block is 23 m/s.

    (a) What is the speed of the bullet when it exits the block?


    (b) Is energy conserved in this collision? (yes or no)

    2. Relevant equations
    (m1)(v1o)+(m2)(v2o)=(m1)(v1)+(m2)(v2)


    3. The attempt at a solution

    (4000)(650)+(0.095)(0)=(4000)(v1)+(0.095)(23)

    v1≈650.00 (Apparently this is wrong.)
     
    Last edited: Oct 25, 2011
  2. jcsd
  3. Oct 25, 2011 #2

    lewando

    User Avatar
    Gold Member

    Your mass units need attention.
     
  4. Oct 25, 2011 #3
    I don't see any mass unit that needs attention. The only thing I did with mass was convert m1 (4.0 g) to the SI unit kg.
     
  5. Oct 25, 2011 #4

    lewando

    User Avatar
    Gold Member

    4g is not 4000kg. :smile:
     
  6. Oct 25, 2011 #5
    Aww crap! Dang, I feel so ridiculous for reversing it up!
     
  7. Oct 25, 2011 #6

    lewando

    User Avatar
    Gold Member

    We all have our moments. That would be some big bullet. No wonder it didn't slow down.
     
  8. Oct 25, 2011 #7
    With the correct unit conversions and your same formula, I got 296.94
     
  9. Oct 25, 2011 #8
    I got 103.75. :confused:
     
  10. Oct 25, 2011 #9
    MV+MV = MV+MV
    .004kg*650m/s + .095kg*0 = .004kg*VF + .095kg*23
    2.6 = .004*VF + 2.185
    .0415 = .004VF
    Vf= 103.75

    0.0 my bad, man sorry about that
     
  11. Oct 25, 2011 #10
    No problem! Thanks for confirming!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Momentum of a Bullet Contacting a Block
Loading...