Physics 9702 · AS & A Level · Linear momentum and its conservation

Linear momentum and its conservation — practice question

(a(i))[2]

State the law of conservation of momentum.

(a(ii))[1]

State how an elastic collision differs from an inelastic collision.

(b(i))[3]

Object A of mass $4.2\text{ kg}$ and horizontal velocity $3.6\text{ m s}^{-1}$ moves towards object B. Object B of mass $1.5\text{ kg}$ has a horizontal velocity of $1.2\text{ m s}^{-1}$ towards object A. The objects collide and afterwards both move to the right. Object A has velocity $v$ and object B has velocity $3.0\text{ m s}^{-1}$. Calculate the velocity $v$ of object A after the collision.

(b(ii))[3]

Determine whether the collision is elastic or inelastic.

(b)

Object A, of mass $4.2\,\text{kg}$ and horizontal velocity $3.6\,\text{m s}^{-1}$, moves towards object B as shown in Fig. 3.1. Object B, of mass $1.5\,\text{kg}$, is travelling with a horizontal velocity of $1.2\,\text{m s}^{-1}$ towards object A. After they collide, both objects move to the right, as shown in Fig. 3.2. Object A has velocity $v$ and object B has velocity $3.0\,\text{m s}^{-1}.$

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: the total momentum of a system stays constant if there is no resultant external force (isolated system)

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