A student wants to find the useful power output of a small electric motor as it lifts a load.

The student has a motor, a power supply, string, a 100 g mass hanger with slotted masses, a balance, a metre rule, a stopwatch and a clamp stand.

Describe how the student could find the useful power output of the motor.

Your answer should include the measurements the student should make and how the student should use them.