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Homework Help: Power problem, need some advice/help

  1. Jan 8, 2007 #1
    1. The problem statement, all variables and given/known data

    Tom's boat is sinking. Water is comming in at a rate of 14.0 liters per minute. He has a pump with a power of 5.0W that pumps water over the high side of the boat. Does the boat sink or stay afloat?

    2. Relevant equations

    Not sure, sorry.

    3. The attempt at a solution

    I belive you need the denisty of water to figure out the mass, and then figure out the Potential gravitational energy, but there is no volume for the boat given so I am clueless to finding the mass.
  2. jcsd
  3. Jan 9, 2007 #2


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    Staff: Mentor

    You are on the right track. It takes some energy to pick up the water and lift it over the side of the boat. You need the height of the water lift (is that given to you, or are you just supposed to assume some height?), and then figure out how much water per second the 5W lets you lift over that height.
  4. Jan 9, 2007 #3
    I actually got the problem.

    I had changed the problem because it was a homework problem and I didn't want to feel like I cheeted, and in the process of changing number I forgot to readd the height of the boat.

    Basically what I did was changed the the 14L/M into Kg/S and used the equation

    P = M * G * H (Gravitational potential) / T

    Got the right answer, with out help! I guess doing physics at night is a bad thing, because my creative thinking is non existant, so figuring out a word problem, obviously, is not going to go so well. Thanks.
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