(a)[1]
State the meaning of the term vector quantity.
(b)
A sphere descends vertically through a liquid of density $830\,\text{kg m}^{-3}$. The sphere has radius $r$ and constant velocity $v$, as shown in Fig. 1.1.
(b(i))[3]
The drag force $D$ on the sphere is described by $D = 6\pi r \eta v$, where $\eta$ is a property of the liquid. Determine the SI base units of $\eta$.
(b(ii))[1]
State an equation giving the relationship between the magnitudes of the weight $W$, drag force $D$ and upthrust $U$ on the sphere.
(b(iii))[2]
The sphere has a volume of $4.6\,\text{cm}^3$. The drag force $D$ is $0.32\,\text{N}$. Calculate the weight of the sphere.
(c(iii))[2]
A sphere has volume $4.6\,\text{cm}^3$. The drag force $D$ is $0.32\,\text{N}$. Calculate the weight of the sphere.