Question

A motor boat moves at a steady speed of 8ms^-1. If the water resistance to the motion of the boat is 2k N, calculate the power of the engine

Answer 1

The boat moves with constant velocity hence the acceleration of the boat is zero hence net external forces should add up to zero. But since there is a resistance of 2kN by water hence the engine must be applying 2kN on boat to maintain equilibrium.
Force applied by engine= 2kN
Power = force applied* velocity of point of application of force(that is boat in the case)
Power= 2kN*8m/s
Power = 16kW by the engine
Hope it helps