An autonomous underwater vehicle is cruising in a straight path at a constant depth. The net force acting on the vehicle is zero, and the net moment acting on it is also zero. Which statement about the vehicle is correct?
It must be stationary.
It is in a state of equilibrium.
Its velocity is continually changing.
Its rotational speed is increasing.
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.