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

Linear momentum and its conservation — practice question

A block $X$ moves along a horizontal frictionless surface towards a block $Y$ that is initially at rest, as shown in Fig. 2.1. No resistive forces act on block $X$ while it travels towards block $Y$. At time $t = 0$, block $X$ has momentum $0.40\,\text{kg m s}^{-1}$. A short time later, the blocks collide and then move apart. Fig. 2.2 shows how the momentum of block $Y$ varies with time $t$.
(a)[1]

Define the term linear momentum.

(b(i))[1]

Use Fig. 2.2 to determine how long the blocks are in contact with each other.

(b(ii)-1)[1]

Describe, without calculation, how the magnitude of the acceleration of block $Y$ behaves from time $t = 80\,\text{ms}$ to $t = 100\,\text{ms}$.

(b(ii)-2)[1]

Describe, without calculation, how the magnitude of the acceleration of block $Y$ behaves from time $t = 100\,\text{ms}$ to $t = 120\,\text{ms}$.

(c)[2]

Use Fig. 2.2 to determine the magnitude of the force exerted by block $X$ on block $Y$.

(d)[3]

On Fig. 2.2, sketch how the momentum of block $X$ varies with time $t$ from $t = 0$ to $t = 160\,\text{ms}$.

(b(ii)1)[1]

Describe, without calculation, how the magnitude of the acceleration of block $Y$ varies from time $t = 80\ \text{ms}$ to $t = 100\ \text{ms}$.

(b(ii)2)[1]

Describe, without calculation, how the magnitude of the acceleration of block $Y$ changes from time $t = 100\ \text{ms}$ to $t = 120\ \text{ms}$.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: Momentum is given by mass multiplied by velocity

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