PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
Consider two bodies, A and B, interacting only with each other in an isolated system.
(i) Write the mathematical form of Newton’s Third Law for the forces between A and B.
(ii) Express each of these forces in terms of the time rate of change of momentum of the corresponding body.
(iii) Combine the results of part (ii) to derive a relation showing that the total momentum of the system remains constant during the interaction.
(iv) State the condition under which the derivation in part (iii) is valid.