Mechanical Energy and Energy Efficiency Theory

Jamie Z 2024-06-10

Learning Goals

• Recognise that energy transfer and transformations are not 100% efficient
• Calculate the energy efficiency for energy transfers and transformations\
• Solve problems using conservation of mechanical energy

Mechanical Energy

Mechanical energy (ME) is the energy that is possessed by an object due to its motion/position

\[ ME = GPE+KE \]

• A ball rolling on the ground has energy in the form of KE and no GPE
• Holding a ball in the air has ME in the form of GPE

Conservation of Energy

• Not all transformations transform one type of energy to another a completely, and in most cases multiple transformations occur
• The law of conservation of energy still applies, so energy input equals total amount of energies transformed
• Input energy = Useful energy + Wasted Energy

Energy Efficiency

The efficiency of an energy transformed is the percentage of INPUT energy that is transformed into useful energy

\[ Energy\ Efficiency = \frac{useful \ energy}{total \ input \ energy} *100 \]