m = 1200 kg, the mass of the boat and its occupants
v = 1.8 m/s, the speed of the boat
The KE (kinetic energy) of the boat is
KE = (1/2)*m*v²
= 0.5*(1200 kg)*(1.8 m/s)²
= 1944 J
To stop the boat, the work done should be equal to the KE of the boat.
Therefore the work done is 1944 J.
Answer: 1944 J