Well, whatever we do we will be wrong because when you have a ship in water there is an effect called usually "added mass" due to having to accelerate water around the ship when you accelerate the ship. However your book did not know that so:
F = m a
-8*10^4 = 3.6*10^7 a
so
a = - (8/3.6)10^-3 m/s^2
v = 1.5 m/s + a t
when v = 0
t = (1.5*3.6*10^3)/8 s
that is the time to stop
d = 1.5 t -(1/2)(8/3.6)10^-3 t^2
that is the distance to stop
) An oil tanker’s engines have broken down, and the wind is blowing the tanker straight toward a reef at a constant
speed of 1.5 m/s (Fig.1). When the tanker is 500 m from the reef, the wind dies down just as the engineer gets the engines
going again. The rudder is stuck, so the only choice is to try to accelerate straight backward away from the reef. The mass of the tanker and cargo is 3.6 * 107 kg, and the engines produce a net horizontal force of 8.0 * 104 N on the tanker. Will the ship hit the reef? If it does, will the oil be safe? The hull can withstand an impact at a speed of 0.2 m/s or less. Ignore the retarding force of the water on the tanker’s hull.
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