Efficiency (Edexcel GCSE Physics): Flashcards

How well a device converts input energy to useful energy

Wastes little energy

Wastes most of its input energy

Dissipated as heat in the surroundings

$\frac{\text{Useful energy}}{\text{Total energy}} \times 100\%$

Joules (J)

Less than 100%

Law of conservation of energy - energy cannot be created

Reduces friction between moving parts, preventing heat loss

Reduces dissipation of thermal energy to surroundings

Friction from moving parts and air resistance

$\text{Total} = \text{Useful Output} + \text{Wasted Energy}$

Streamline shapes