Year 9 Science · Unit 3 · Lesson 7
Challenge Worksheet
Learning Goals
1. In one line each, define temperature, thermal energy and heat.
Find the error: four statements from a group chat
(a) “A teaspoon of tea at 90 °C has more thermal energy than a full teapot of the same tea at 85 °C, because it is hotter.”
(b) “Put a wool blanket over the ice-cream tub to keep the cold in.”
(c) “Once the milk and the tea are at the same temperature, heat keeps flowing from the tea into the milk.”
(d) “The Sun heats Earth by convection through space.”
2. Each statement contains one error. Say what is wrong, and rewrite the statement correctly.
| Part | What is wrong | Correct statement |
|---|---|---|
| (a) | ||
| (b) | ||
| (c) | ||
| (d) |
3. A spark at 1,000 °C lands on the surface of Sydney Harbour, where the water is at 22 °C. (a) Which has more thermal energy, the spark or the harbour? (b) Which way does heat flow? (c) Does the harbour’s temperature change noticeably? Justify each answer using particle number, mass and average kinetic energy.
Data: does a foam can holder stop heat getting in?
A class took two cans of drink from a fridge at 4 °C. One can was put in a foam can holder; the other was left bare. Both stood on a bench in a room at 24 °C.
| Time (min) | Bare can (°C) | Can in foam holder (°C) |
|---|---|---|
| 0 | 4 | 4 |
| 10 | 11 | 7 |
| 20 | 16 | 10 |
| 30 | 19 | 12 |
| 40 | 21 | 14 |
| 60 | 23 | 17 |
Source: sample class results.
4. Calculate how much each drink warmed up in the first 60 minutes, and how many degrees less the drink in the holder warmed.
Bare can °C
Can in holder °C
Difference °C
5. Name two ways heat gets into the bare can. For each one, explain how the foam holder reduces it.
6. A student claims: “The foam holder stops heat getting into the drink.” Use the data to evaluate this claim. Predict the temperature of both drinks after 4 hours, and explain.
7. “A thermometer measures temperature, not heat or thermal energy.” Evaluate this statement. Explain what a thermometer’s reading tells you about the particles, and why it cannot tell you how much thermal energy an object has without more information.