Unit 3: Forces and energy
Heat And Temperature — HIA International - Grade 8 Revision Notes & Topical Questions
5 min read 8 parts Lesson 10 of 16 2 quizzes
Lesson summary
Heat and temperature — HIA INTERNATIONAL notes: Distinguish heat from temperature and explain the direction of thermal energy transfer.Thermal energy — it can be transferred between objects and stored, but eventually dissipates into the surroundings; it is measured in joules.Part…
- More particles
- Comparison
- Bath vs cup
- Little heat
- Fast transfer
- Slower particles
Part 1 of 6Heat
Heat
Thermal energy
- Thermal energy it can be transferred between objects and stored, but eventually dissipates into the surroundings;
- it is measured in joules.
Particles
- Particles when thermal energy increases, the particles vibrate faster.
Heat
Heat the total thermal energy of the vibrating particles in an object.
More particles
- More particles a larger volume of water at the same temperature has more heat than a smaller volume.
Hotter
- Hotter for the same number of particles, the hotter water has more heat.
Part 2 of 6Temperature
Temperature
Temperature the average energy of the particles in an object.
Direction
- Direction it tells you which way thermal energy will be transferred, from high to low temperature.
Rate
- Rate the bigger the temperature difference, the faster the thermal energy transfer.
Comparison
- Comparison temperature compares particle energy between objects of different size or material.
Unit
- °C, measured with a thermometer.
Part 3 of 6Heat compared with temperature
| Quantity | Measures | Unit |
|---|---|---|
| Heat | Total energy of all the particles | Joules (J) |
| Temperature | Average energy of the particles | Degrees Celsius (°C) |
- Bath vs cup
- a bath of warm water at 40 °C has more heat than a cup of boiling water at 100 °C because it has many more particles.
Part 4 of 6Sparkler
Temperature
- Temperature a sparkler spark is about 1000 °C.
Little heat
- Little heat a spark has a very small mass, so very few particles and a very small total energy.
Fast transfer
- Fast transfer the large temperature difference with the air means the spark cools quickly, so it does not cause serious burns.
Part 5 of 6Absolute zero
Absolute zero
Slower particles
- Slower particles as temperature decreases, the particles move more slowly.
Kelvin
- Kelvin predicted that particles would stop moving at the lowest possible temperature.
Absolute zero
−273 °C.
Reality
- Reality scientists have reached within billionths of a degree of it but cannot make particles stop completely.
Part 6 of 6Measuring heat and temperature
1
Put a known mass of water in a polystyrene cup.
2
Record the starting temperature and set the joulemeter to zero.
3
Switch on the immersion heater and start the timer.
4
Stir and record the temperature and joulemeter reading every minute.
5
Continue until the temperature has risen by 10 °C, then switch off.
6
Plot temperature against energy.
Safety
- Safety do not touch the immersion heater while it is switched on.
Losses
- Losses some thermal energy heats the cup, stirrer and air.
Key terms
| Term | Meaning |
|---|---|
| Heat | The total thermal energy of the vibrating particles in an object. |
| Temperature | The average energy of the particles in an object. |
| Thermal energy | Energy stored in hot objects, measured in joules. |
| Absolute zero | The lowest possible temperature, −273 °C. |
| Temperature difference | How much hotter one object is than another. |
| Joule | The unit of energy. |
Avoid these mistakes
1
Heat and temperature are the same — heat is total energy; temperature is average energy.
2
A higher temperature always means more heat — a larger mass at a lower temperature can have more heat.
3
Cold flows into things — cold means less thermal energy; energy flows from hot to cold.
4
Temperature is measured in joules — temperature is in °C and heat in joules.
Marked practiceQuizzes for this lesson
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