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Find velocity of boat as function of the time

  • #1
ays
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Homework Statement


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

Homework Equations


ƩF = ma
a = dv/dt

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
 

Answers and Replies

  • #2
TSny
Homework Helper
Gold Member
12,322
2,809
Hello.

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

ΣFx = max

ΣFy = may
 
  • #3
I think that you should not consider mg as it is in 90° angle with rv
 
  • #4
jbriggs444
Science Advisor
Homework Helper
2019 Award
8,110
2,940
I think that you should not consider mg as it is in 90° angle with rv
And it is in equilibrium with buoyancy.
 

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