A motorboat starts from rest on a calm lake. Its engine exerts a constant forward thrust. The water exerts a resistive drag force on the boat that is proportional to its speed.
Why does the boat eventually reach a constant maximum speed?
The resistive force decreases until the acceleration of the boat becomes negative.
The resistive force decreases until the acceleration of the boat becomes zero.
The resistive force increases until the acceleration of the boat becomes negative.
The resistive force increases until the acceleration of the boat becomes zero.
245 exam-style questions on CIE IGCSE Physics 1.5 Forces, covering 1.5.1a Forces, resultant force and motion, 1.5.1b Load–extension graphs and the spring constant, 1.5.1c Friction and drag, 1.5.1d Force, mass and acceleration, 1.5.1e Motion in a circular path, 1.5.2a Moment of a force, 1.5.2b Principle of moments and equilibrium, and 1.5.3 Centre of gravity and stability. Each one has a worked solution and a mark scheme showing where the marks go.