A uniform wooden plank is balanced horizontally on a pivot at its centre of mass. A heavy crate is placed on one side of the pivot, and a lighter box is placed on the other side. The system remains balanced and in static equilibrium.
Which statement must be true?
The distance of the crate from the pivot is equal to the distance of the box from the pivot.
The weight of the crate is equal to the weight of the box.
The resultant force on the plank is zero and the resultant moment about the pivot is zero.
The downward force of the crate is equal to the upward force exerted by the pivot.
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.