Year 9 Science · Unit 3 · Lesson 9
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word or words from the word bank. Each one is used once. Two will not be used.
In the equation Q = mcΔT, Q is the transferred, measured in . m is the in kilograms, c is the in J/kg·°C, and ΔT is the in °C.
True or false? Fix the false ones
Circle T or F. If a statement is false, correct it on the line.
Water heats up faster than sand because water has a very high specific heat capacity.
Correct it:
Coastal cities like Sydney have milder temperatures than inland towns partly because the ocean has a high specific heat capacity.
Correct it:
A material with a low specific heat capacity needs only a little energy to warm 1 kg of it by 1 °C.
Correct it:
A cast-iron frypan heats up slowly because iron has a very high specific heat capacity.
Correct it:
1. Water has a specific heat capacity of 4,200 J/kg·°C. What does this number tell you?
2. A saucepan holds 1.5 kg of water at 20 °C. Calculate the energy needed to bring it to the boil at 100 °C. Use c = 4,200 J/kg·°C for water (the lesson’s value). First find ΔT, then use Q = m × c × ΔT.
ΔT °C
Energy J
3. A 1 kg aluminium pan (c = 900 J/kg·°C) and a 1 kg iron pan (c = 450 J/kg·°C) each take in 9,000 J of energy. Use ΔT = Q ÷ (m × c) to calculate the temperature rise of each pan.
Aluminium pan °C
Iron pan °C
Data: the same energy, four materials
Each material below, 1 kg of it, takes in 16,800 J of energy.
| Material | c (J/kg·°C) | Temperature rise (°C) |
|---|---|---|
| Water | 4,200 | 4.0 |
| Iron | 450 | |
| Sand | 800 | |
| Glass | 840 |
Source: specific heat capacities used in Lesson 9.
4. Complete Table 1. Round to one decimal place. Water is done for you: 16,800 ÷ (1 × 4,200) = 4.0 °C.
5. At the beach, dry sand and the sea receive the same sunshine all day. Use Table 1 to explain why the sand gets much hotter than the water.
6. Explain why a hot-water bottle is filled with water rather than iron beads. Calculate the energy given out by 1 kg of water, and by 1 kg of iron, as each cools from 60 °C to 30 °C, and use your answers. Use c = 4,200 J/kg·°C for water (the lesson’s value). For iron, c = 450 J/kg·°C.
Energy from 1 kg of water J
Energy from 1 kg of iron J