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Find velocity of boat as function of the time

  1. Jun 6, 2017 #1

    ays

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    1. The problem statement, all variables and given/known data
    a motorboat of mass m moves along a lake with velocity Vi. at the moment t=0 the engine of the boat is shut down, assuming the resistance of water to be proportional to the velocity of the boat f= -rv , find the velocity of the boat as a function of time

    2. Relevant equations
    ƩF = ma
    a = dv/dt

    3. The attempt at a solution
    ƩF = ma
    - mg - rv = ma
    dv/dt = (-mg - rv)/m
    am not sure if i am going the right way or not
     
  2. jcsd
  3. Jun 6, 2017 #2

    TSny

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    Homework Helper
    Gold Member

    Hello.

    Force and acceleration are vector quantities. You should work with components:

    ΣFx = max

    ΣFy = may
     
  4. Jun 6, 2017 #3
    I think that you should not consider mg as it is in 90° angle with rv
     
  5. Jun 7, 2017 #4

    jbriggs444

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    Science Advisor

    And it is in equilibrium with buoyancy.
     
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