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Homework Help: Momentum Poblem Need help

  1. Nov 9, 2004 #1
    Momentum Poblem.. Need help!!

    A 1.5 kg cart is propelled forward by a series of 85g balls being ejected from the rear of the cart with a speed of 3.5 m/s relative to the cart. Calculate the speed of the cart after three balls have been ejected. Compare this to the speed of the cart if it had ejected a signle 255g ball at 3.5 m/s relative to the cart. Assume negligible friction, calculate the final velocity for each cart?

    i have got an answer but the relationship is wrong the first cart should have the faster velocity... anyone help i need to understand this!!!
     
  2. jcsd
  3. Nov 9, 2004 #2
    mv=mv
    First Ball:
    1.415kg(v)=(0.085kg)(3.5m/s)
    solve for v then just do the same for second+third

    mv=mv
    1.245kg(v)=(0.255kg)(3.5m/s)
    solve for v
     
  4. Nov 9, 2004 #3
    umm... that's not it... it's suppose to be relative to the cart.. i know this cause i did something similar to urs and i got it wrong..
    and by the way the mass of balls are seperate...
     
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