An engineering firm is testing different prototype DC electric motors to be used in a vertical hoist system.

Plan an investigation to determine and compare the average mechanical power output and the overall energy efficiency of each motor when lifting a load.

In your answer, you should:

• State the physical measurements that must be taken and the equipment used to measure them.
• Explain how these measurements are used to calculate the average mechanical power output and the efficiency of each motor, writing down the relevant equations.
• Identify how to make the investigation a fair and reliable comparison.