Year 9 Science · Unit 3 · Lesson 10
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word from the word bank. Each word is used once. Two words will not be used.
When steel railway tracks are heated by the sun, the energy makes the particles in the metal more vigorously. The average between neighbouring particles increases, so the whole track undergoes : it gets slightly longer. In cold weather the particles vibrate less and the track will , becoming shorter. Engineers leave a small gap at each expansion so that the track can expand in summer without buckling. A strip, which bends when heated, is used in thermostats to control temperature automatically.
1. Use particle theory to explain why a steel railway track gets longer on a hot summer day. Say what the particles do, and what does NOT happen to them.
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
Liquids expand more than gases when heated by the same temperature rise.
Correct it:
All materials expand by the same amount when heated by 1 °C.
Correct it:
Expansion joints in bridges let the structure expand and contract safely without cracking.
Correct it:
Thermal expansion happens because particles get physically larger when they are heated.
Correct it:
When a material cools, its particles vibrate less and move closer together, so it contracts.
Correct it:
2. A 10 m steel rail warms from 10 °C at dawn to 40 °C in the afternoon. Steel grows by 0.012 mm for each metre of length, for each 1 °C it warms (the lesson’s value). Calculate (a) the temperature rise and (b) how much longer the rail gets, in millimetres.
(a) Temperature rise °C
(b) The rail grows by mm
3. A steel lid is stuck tight on a glass jar. Running hot water over the lid helps to open it. Steel expands more than glass. Explain why the hot water helps.
Investigation: heating a copper tube
A class passed hot water through a copper tube 1.000 m long. A dial gauge measured how much longer the tube became for different temperature rises.
| Temperature rise (°C) | Increase in length (mm) | Increase for each 1 °C (mm) |
|---|---|---|
| 20 | 0.34 | 0.017 |
| 40 | 0.69 | |
| 60 | 1.01 | |
| 80 | 1.37 |
Source: sample class results.
4. Complete the last column of Table 1. Round to 3 decimal places. Describe the pattern: what happens to the expansion when the temperature rise doubles?
5. A steel tube of the same length is tested with a 50 °C rise. Use the steel value in Question 2 to calculate its expansion, and say whether it expands more or less than the copper tube would.
Steel tube mm
6. The concrete slabs of a school basketball court have narrow gaps between them, filled with soft rubber. Explain what happens to the slabs and the gaps in summer and in winter, and what could happen if the slabs were laid with no gaps. Use particle theory.