CAIE A-Level Physics 4.3.1 Density

Practise defining and calculating density from mass, volume and object dimensions, rearranging the relationship for composite or mixed materials.

Exam points

define density as mass per unit volume and use ρ = m/V with coherent units
calculate volume from object geometry or measurements before using ρ = m/V to determine density
rearrange ρ = m/V to find mass, volume or a missing dimension, including composite or mixed materials where the relevant masses and volumes must be combined

[Maximum number: 2]

A cylinder is suspended from the end of a string. The cylinder is stationary in water with the axis of the cylinder vertical, as shown in Fig. 2.1.

Fig. 2.1 (not to scale)

The cylinder has weight 0.84 N , height h and a circular cross-section of diameter 0.031 m . The density of the water is $1.0 \times 10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$ . The difference between the pressures on the top and bottom faces of the cylinder is 520 Pa .

Calculate the height h of the cylinder.

h =m [2

$\begin{aligned} (\Delta) p=\rho g(\Delta) h 520=1000 \times 9.81 \times h \end{aligned}$

C1

$h=0.053 \mathrm{~m}$

A1

All question bank results loaded

4.3.1—Density question 1