A box is depicted at rest on the ground. Newton’s third law shows that there are four forces of equal magnitude. These forces are called P, Q, R and S. P and Q act on the box, whereas R and S act on the Earth. To make the diagram clearer, the forces are drawn a little apart. Which statement about the forces is correct?
- AP is the equal and opposite force to Q and both are forces of contact.
- BQ is the equal and opposite force to P and both are gravitational forces.
- CR is the equal and opposite force to S and both are forces of contact.
- DS is the equal and opposite force to Q and both are gravitational forces.