Mechanics: Efficiency

Energy Transfers and Efficiency

Understand that an energy transfer occurs when energy is passed from one type of energy to another.
Familiarise yourself with the principle of conservation of energy. It states that energy cannot be created or destroyed, only transferred or stored.
Recognise that whenever an energy transfer occurs, there will always be some energy wasted, often in the form of heat energy.
Appreciate the concept of efficiency. Efficiency is the ratio of useful energy output to the total energy input, and it can never be more than 100% due to the energy wasted.
The formula for efficiency is useful power output / total power input.

Identify that mechanical efficiency refers specifically to the efficiency of a machine or system to convert the input energy into output work.
Understand that there may be losses in mechanical systems due to friction, air resistance, or other factors.
Make a note that the efficiency of a mechanical system can be improved by reducing losses. This often involves reducing friction by using lubricants or making components more streamlined to reduce air resistance.

Be aware of the practical implications of efficiency. High efficiency can result in cost savings, while low efficiency can lead to wastage of resources.
Practice efficiency calculations. These are a common exam question and it’s important you can confidently solve them. Remember that efficiency is often expressed as a percentage.
Understand that for some systems like car engines, the efficiency can be very low. This is due to energy losses in different parts of the system, which results in a considerable waste of fuel.

Realise the importance of efficiency in terms of sustainability. More efficient systems use less energy, reducing the demand on resource consumption and lowering environmental impact.
Note that a key part of many gadgets and systems is continually improving their efficiency. This is part of a global push towards more sustainable and green technology and practices.