Which of the following moving objects has a non-zero resultant force acting on it?
A lift moving vertically upwards at a constant speed
A skater gliding in a straight line at a constant speed
A satellite orbiting the Earth in a circular orbit at a constant speed
A hot-air balloon descending vertically at terminal velocity
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.