Reducing unwanted energy transfers (Edexcel GCSE Physics Combined Science): Revision Notes
📚 Revision Notes
Reducing unwanted energy transfers
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No device is 100% efficient, but we can reduce the amount of energy wasted to make devices more efficient. Reducing wasted energy means more of the input energy is transferred to useful energy stores, increasing efficiency.
Two main ways to reduce unwanted energy transfers are lubrication and thermal insulation:
1. Lubrication:
What it does: Lubrication reduces friction between moving parts in a machine, so less energy is wasted as heat.
How it works:
- Friction causes energy to be transferred to the thermal energy store of the objects involved, and this energy is lost to the surroundings as heat.
- Lubricants, like oil, reduce this friction, allowing parts to move smoothly and reducing the heat energy lost.
- Lubricants are usually liquids, which allows them to flow between objects and coat them, further reducing friction.
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Example: In a car engine, oil is used to reduce the friction between moving parts, which keeps the engine cooler and more efficient.
2. Thermal Insulation:
What it does: Insulation reduces the rate of heat energy transfer from objects to their surroundings.
How it works:
- When one side of an object is heated, the particles vibrate more and collide with nearby particles, transferring energy. This process is called conduction.
- Insulation materials slow down this transfer of energy by using materials with low thermal conductivity. The lower the thermal conductivity, the slower the heat transfer.
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Examples in Homes:
Why is this important?
- Decreasing the amount of wasted energy increases efficiency. More energy is transferred to useful stores, meaning devices and systems can perform better while using less energy.