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Physics Project Conservation of momentum,energy, and projectile motion

  1. Nov 11, 2009 #1
    For my AP Physics Class we were given spring loaded nerf guns and asked to find a spring constant and the acceleration of the bullet before it hit the block. We had to hit a target that was on the edge of our desk and record the distance when the bullet stuck to the target. I have worked more than halfway through the problem, but have trouble when it comes to the conservation of energy and can't seem to find the acceleration.

    Mb=.0136 kg
    Mt=.2392 kg
    X(Desk to landing place)=.3825 m
    Y(Top of target to floor)=.82

    To find time it takes for the bullet/target combo to reach the floor I used the y-component
    Xy=XoY+Vo(t)+1/2(a)(t)2
    0=.82+1/2(-9.81)(t)2
    T=-.82/-4.905=.409

    To find velocity of the bullet/target combo I substituted time into the x-component
    X=Xo+Vo(t)+1/2(a)(t)2
    .3852= Vo(.409)
    Vo=.935

    To find the velocity of the bullet before it hit the target I used the conservation of momentum
    MbVb+ MtVt=( Mb+ Mt)Vo
    .0136Vb+.2392(0)=(.0136+.2392).935
    Vb=17.38
     
    Last edited: Nov 11, 2009
  2. jcsd
  3. Nov 12, 2009 #2
    Ohh I forgot the spring is compressed 0.06 meters and the distance from the tip of the gun to the block is 1.77 meters.
     
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