PHYSICS · Stage 9 · Chapter 12: Energy Transfer
Physics 12.1 Hot and cold — Temperature (°C) vs Thermal Energy (J)
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Lesson summary
Physics 12.1 Hot and cold — Temperature (°C) vs Thermal Energy (J) — Alhussan International Academy — Physics (Stages 7–9) notes: Describe the difference between temperature and thermal energy, how particles behave on heating and how energy is dissipated.Temperature = a measure o…
- Liquid-in-glass thermometer
- Digital thermometer
- Thermal image
- Typical values
- Pool and cup
- Liquids and gases
Section 1 of 5Temperature
- Temperature = a measure of how hot or cold something is, measured in degrees Celsius (°C).
- Liquid-in-glass thermometer
- A liquid in a very narrow glass tube expands when heated and rises up the scale.
- Thermometers used to contain mercury, which is poisonous, so alcohol is now used.
- Digital thermometer
- It uses a sensor to measure temperature directly.
- Thermal image
- A special camera shows differences in temperature, such as a cold scorpion held by a warm person.
- Typical values
- Human body temperature is 37 °C.
- The coldest recorded temperature on Earth was −89.2 °C in Antarctica in 1983.
- The hottest was 56.7 °C in Death Valley, USA in 1913.
Section 2 of 5Temperature and thermal energy
| Temperature | Thermal energy |
|---|---|
| How hot or cold something is | Total energy in the thermal store |
| Unit: °C | Unit: joule (J) |
| Measured with a thermometer | Depends on the amount of material |
| Does not depend on the amount of material | Larger for more particles |
- Pool and cup
- A cup of warm water and a swimming pool can have the same temperature, but the pool's thermal store holds much more energy.
Section 3 of 5Heating and particles
- Solid
- Heating makes particles vibrate more.
- Liquids and gases
- Heating makes particles move faster.
- Temperature
- It is related to the average speed of the particles.
- Individual particles
- You cannot say that an individual particle gets hotter; each can only move or vibrate faster, and temperature is a property of the whole substance.
Section 4 of 5Energy needed to raise the temperature
- Mass
- A greater mass has more particles, so more energy is needed.
- Type of material
- If the particles are more massive, more energy is needed.
- Temperature rise
- A bigger temperature rise needs more energy.
- Heating water
- Energy from burning fuel is transferred to the water, raising its temperature.
Section 5 of 5Cooling and dissipation
- Direction
- Energy is always transferred from a hot object to a cold object.
- Hot pan in cold water
- The water gets hotter and the pan cools as energy passes from the pan to the water.
- A hot object with ice in it transfers energy to the ice, which melts while the water cools.
- Thermal equilibrium
- Transfer stops when both objects are at the same temperature.
- Dissipation = energy moving from a hot region to a cold region and spreading out.
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