Physics 5054 · O Level · Momentum

Momentum — practice question

A car is stationary on a straight horizontal road. At time t = 0, the car starts to accelerate. Figure 1.1 illustrates how the car’s momentum changes with time.
(a)[3]

From Fig. 1.1, determine the resultant force on the car over the initial 1.5 s of its motion.

(b(i))[2]

The car has mass m. If the car’s momentum is p, its kinetic energy is $E_k$. Show that $\frac{p^2}{2m}=E_k$.

(b(ii))[3]

At $t=6.0\,\text{s}$, the car’s kinetic energy is $5.4\times10^5\,\text{J}$. From Fig. 1.1, determine the momentum p of the car at $t=6.0\,\text{s}$, then use the equation in (b)(i) to determine the mass m of the car. Show your working.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Change in momentum is 18 000 kg m/s

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