(a(i))[3]
Show that the SI base units of $D$ are $\text{kg m}^{-1}\,\text{s}^{-1}$.
(a(ii).1)[1]
A raindrop with radius $1.5\,\text{mm}$ is falling vertically through air at a speed of $3.7\,\text{m s}^{-1}$. For air, $D = 6.6 \times 10^{-4}\,\text{kg m}^{-1}\,\text{s}^{-1}$. Water has density $1000\,\text{kg m}^{-3}$. Calculate the magnitude of the frictional force $F$.
(a(ii).2)[3]
Calculate the acceleration of the raindrop.
(b(i))[3]
The speed $v$ of the raindrop in (a) changes with time $t$ as shown in Fig. 2.1. State how the raindrop’s acceleration varies with time.
(b(ii))[2]
A second raindrop has a radius smaller than the one in (a). On Fig. 2.1, sketch how the speed varies with time for this second raindrop.