A boat has mass m=1000 kg and is moving at velocity v0=324 ms^-1. Friction force btw the boat and water is proportional to velocity v, Fd=70*v. How long it takes to slow down to 162ms^-1 ?
I'm not sure which function should I integrate, because acceleration is not constant.
The Attempt at a Solution
I understand Friction force and acceleration as functions of v, but I have no idea how to express these as functions of time, since acc is not constant. Then I would integrate a(t) with respect to time and substitute final velocity for v(t) and from that I'd get the answer.