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Homework Help: Net power H E L P ! ! !

  1. Oct 6, 2004 #1
    A car (m = 760 kg accelerates uniformly from rest up an inclined road which rises uniformly, to a height, h = 44 m. Find the net power the engine must deliver to reach a speed of 20.7 m/s at the top of the hill in 22.5s (NEGLECT frictional losses: air and rolling, ...)

    I know that W_n=Triangle_K (change in K) which is 1/2*m*(V_f^2-V_i^2) where V_i = 0
    and I also have that W_g+W_f=1/2 m

    I tried solving with that , but I dont get it right

    What am I doing wrong?; Also what do I use Velocity and Time for?( I know what for , but where in the equations do I use it if it is to be used).
     
  2. jcsd
  3. Oct 6, 2004 #2

    NateTG

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    You're missing some of the terms in your work-energy equation since the car is going uphill.

    The equation should be:
    [tex]\Delta E = W_{net}[/tex]
     
  4. Oct 6, 2004 #3
    I still dont get it after that...
     
  5. Oct 6, 2004 #4

    NateTG

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    Can you set up the energy equation? You should get about [tex]4.9 \times 10^5[/tex] joules.
     
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