A box is shown resting on the ground. Newton’s third law implies that four forces of equal magnitude are involved. These forces are labelled P, Q, R and S. Forces P and Q act on the box. Forces R and S act on the Earth. For clarity, the forces are shown slightly separated.
Which statement about the forces is correct?
P is the equal and opposite force to Q and both are forces of contact.
Q is the equal and opposite force to P and both are gravitational forces.
R is the equal and opposite force to S and both are forces of contact.
S is the equal and opposite force to Q and both are gravitational forces.
