1. Not finding help here? Sign up for a free 30min 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!

Help! Force and simple dynamics

  1. Jan 26, 2009 #1
    1. The problem statement, all variables and given/known data
    A bullet of mass 0.002 kg initially moving at 510 m/s embeds itself in a large fixed piece of wood and travels 0.78 m before coming to rest. Assume that the acceleration of the bullet is constant.


    2. Relevant equations
    What force is exerted by the wood on the bullet?


    3. The attempt at a solution
    In order to find the force, I had to solve for acceleration using the velocity vs function equation: v^2=V0^2 + 2a[tex]\Deltax[/tex]
    a=v^2-V0^2/2[tex]\Deltax[/tex]
    a=0-(510)^2/2(.78)
    I plugged in the numbers to the equation f=ma, but it doesnt work. Can anybody help me?
     
  2. jcsd
  3. Jan 26, 2009 #2

    nvn

    User Avatar
    Science Advisor
    Homework Helper

    It seems to work fine using the equations you posted, which seem correct. Can you show your work, and explain what you mean by the statement, "It doesn't work"?
     
  4. Jan 26, 2009 #3
    a=0-(510)^2/2(.78)
    a=-166730.76
    f=0.002kg * -166730 m/s^2
    f=-333.46

    I entered this answer into my homework online and it is incorrect
     
  5. Jan 27, 2009 #4

    nvn

    User Avatar
    Science Advisor
    Homework Helper

    Nice work; your answer is correct. Should you include units when you enter an answer into your homework on-line? If so, add capital N, for newtons. If that fails, try removing the negative sign (even though the negative sign is correct). If that fails, try entering your answer to only three significant digits, instead of five. If that fails, the on-line program might be wrong or malfunctioning.
     
    Last edited: Jan 27, 2009
  6. Jan 27, 2009 #5
    Thanks! the answer is 333 N
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Help! Force and simple dynamics
Loading...