A car travelling at 20 m s⁻¹ collides with a stationary truck and comes to rest. Explain the difference between the car’s total momentum before the collision and the change in its momentum during the collision.

The car’s total momentum before the collision is the product of its mass and its initial velocity (p = mv). The change in momentum (Δp) is the difference between the final and initial momentum, which in this case is the negative of the initial momentum because the final momentum is zero. Thus, total momentum refers to the momentum at a specific instant, while change in momentum refers to how much the momentum has altered as a result of the collision.

This answer correctly identifies that total momentum is a snapshot value (mv) and that change in momentum is the difference between final and initial values, demonstrating understanding of the vector nature of momentum and the concept of impulse.