1. The problem statement, all variables and given/known data A 1150 kg boat is traveling at 100 km/h when its engine is shut off. The magnitude of the frictional force k between boat and water is proportional to the speed v of the boat: f_k = 73v, where v is in meters per second and f_k is in newtons. Find the time required for the boat to slow to 41 km/h. 2. Relevant equations 3. The attempt at a solution Quite honestly, I don't even know where to begin with this problem. I started to write down: F_net,x = (1150)*(a) = F_app - f_k Since we are dealing with the force of friction f_k against the applied force of the boat's engin, F_app. So we would solve for 'a', but the applied force F_app is unknown, and the friction is dependent on the current velocity, so it's not exactly applicable unless we have the velocity at every given point.. Makes me think I have to take it's integral, but that would be it's position, not it's acceleration..