A heavy wooden crate rests on a rough, horizontal floor. A student pushes the crate with a constant horizontal force FFF, but the crate remains stationary due to a frictional force fff. Which of the following pairs of forces constitutes a Newton’s third law action-reaction pair?
The upward normal reaction force exerted by the floor on the crate and the downward gravitational force exerted by the Earth on the crate.
The horizontal force FFF exerted by the student on the crate and the frictional force fff exerted by the floor on the crate.
The downward gravitational force exerted by the Earth on the crate and the upward gravitational force exerted by the crate on the Earth.
The upward normal reaction force exerted by the floor on the crate and the downward normal force exerted by the floor on the ground.
16 exam-style questions on OCR GCSE Physics Newton’s laws. Each one has a worked solution and a mark scheme showing where the marks go.