A motorboat travels in still water at a constant speed of while the engine delivers a…
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A motorboat travels in still water at a constant speed of 5.0ms−1 while the engine delivers a steady power of 8.0kW. Over the range of speeds considered, the resistive drag force of the water on the hull is proportional to the square of the boat’s speed.
(a) Determine the magnitude of the resistive drag force acting on the boat when it is moving at 5.0ms−1.
(b) If the engine power is increased to 16kW, calculate the new constant speed at which the boat can travel, assuming the same drag–speed relationship.
(c) Explain why doubling the engine’s power does not result in the boat’s speed doubling.