Question

A team of engineers designs a small wind turbine to power lights in a park. During testing, they measure the mechanical energy from the spinning blades and the electrical energy produced for the lights. They discover that the electrical energy output is less than the mechanical energy input from the blades.

Which explanation best applies the Law of Conservation of Energy to this situation?
Responses

A Some mechanical energy was destroyed during the transformation.Some mechanical energy was destroyed during the transformation.

B Mechanical energy transformed into electrical energy, and some converted into sound and heat due to friction in the turbine system.Mechanical energy transformed into electrical energy, and some converted into sound and heat due to friction in the turbine system.

C The electrical energy came entirely from the wind without using mechanical energy.The electrical energy came entirely from the wind without using mechanical energy.

D The Law of Conservation of Energy only applies to closed laboratory experiments.

Answer 1

B

Mechanical energy from the blades is converted to electrical energy, but not all of it becomes electricity. Some is dissipated as heat (friction in bearings and the generator windings), sound, and turbulent air losses. The total energy is conserved — it’s just distributed among electrical energy and other forms.