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What is the speed of the boat after time 2.00 hr has passed?

  1. Sep 20, 2007 #1
    Can you please help me out with the second part of this question? I got the first two parts. Its PART C that I am not getting. Thanks!

    A boat of mass 250 kg is coasting, with its engine in neutral, through the water at speed 3.00 m/s when it starts to rain. The rain is falling vertically, and it accumulates in the boat at the rate of 10.0 kg/hr.

    Part A
    What is the speed of the boat after time 2.00 hr has passed? Assume that the water resistance is negligible.

    Part B
    Now assume that the boat is subject to a drag force F_d due to water resistance. Is the component of the total momentum of the system parallel to the direction of motion still conserved?

    Part C
    The drag is proportional to the square of the speed of the boat, in the form F_{\rm d}= 0.5 v^2. What is the acceleration of the boat just after the rain starts? Take the positive x axis along the direction of motion.
    Express your answer in meters per second per second.


    Its Part C that I am not getting. Please help. Thanks!!


    Thank-you very much for all your time and effort!!
     
    Last edited by a moderator: Jan 7, 2014
  2. jcsd
  3. Sep 20, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Use Newton's 2nd law.
     
  4. Oct 1, 2008 #3
    Re: Conservation of Momentum

    Is the component of the total momentum of the system parallel to the direction of motion still conserved?

    I do not get part B, the part where the system is parallel to the direction of motion. can anyone explain??

    do i think of the boat and the drag force as a collision? therefore, total momentum is conserved?
     
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