A workshop is sorting unlabelled metal blocks for use as counterweights. A technician measures the mass of each block with a balance. The blocks are rectang...
Question 1 Report
A workshop is sorting unlabelled metal blocks for use as counterweights. A technician measures the mass of each block with a balance. The blocks are rectangular, so their volume is calculated from length × width × height. Table 1 gives the measurements. The density of aluminium is 2.7 g/cm3, and the density of brass is 8.5 g/cm3.
| block | mass / g | length / cm | width / cm | height / cm |
|---|---|---|---|---|
| P | 54 | 5.0 | 2.0 | 2.0 |
| Q | 170 | 5.0 | 2.0 | 2.0 |
| R | 81 | 6.0 | 2.5 | 2.0 |
(a) Calculate the volume of block Q. [2]
(b) Calculate the density of block Q. [2]
(c) Which block, P, Q or R, is made of brass? Use data from Table 1. [2]
(d) Explain why blocks with the same volume can have different masses. [2]
(e) State the SI unit of density. [1]
Answer Details
(a) The volume of a rectangular block is \(l\times w\times h\):
\[V=5.0\text{ cm}\times2.0\text{ cm}\times2.0\text{ cm}=20\text{ cm}^3\]
[2]
(b)
\[\rho=\frac{m}{V}=\frac{170\text{ g}}{20\text{ cm}^3}=8.5\text{ g/cm}^3\]
[2]
(c) Block Q is brass. Its calculated density is \(8.5\text{ g/cm}^3\), equal to the given density of brass. [2]
(d) Blocks of equal volume can be made from different materials. Different materials have different densities, so the same volume can contain different masses. [2]
(e) The SI unit of density is \(\text{kg/m}^3\). [1]
Download The App On Google Playstore
Everything you need to excel in your exams
