State the meaning of the mass of a body.
Two blocks move straight towards each other on a horizontal, frictionless surface. Use Newton’s third law to explain why, during the collision, the change in momentum of block A is equal and opposite to the change in momentum of block B.
Determine the speed $v$ of block B after the collision.
Two blocks move straight towards each other on a horizontal, frictionless surface. The blocks collide, as shown in Fig. 3.1. Block A has mass $3M$ and block B has mass $M$. Before the collision, block A travels to the right at a speed of $0.40\,\text{m s}^{-1}$ and block B travels to the left at a speed of $0.25\,\text{m s}^{-1}$. After the collision, block A travels to the right at a speed of $0.20\,\text{m s}^{-1}$ and block B travels to the right at speed $v$.
Calculate, for the blocks, the relative speed of approach.
Calculate, for the blocks, the relative speed of separation.
Use your answers in (b)(iii) to state and explain whether the collision is elastic or inelastic.