A Student Performs an experiment in which an electric motor is used to lift a 200g weight through 2m, thus increasing its potential energy by 4j. From measurements of the rate at which the weight is lifted the efficiency of the motor is to be determined. Two different voltages were used an the current was measured.
In the first experiment at 6V, a current of 0.25A was measured and the weight took 5 seconds to rise the 2 metres. What was the efficiency of the motor?
In the Next experiment the voltage was increased to 8V, the current was found to be 0.30A and the efficiency worked out to be 60%. How long did the motor take to lift the weight the 2m this time?
The Attempt at a Solution
I have no idea even how to work out efficiency yet so my attempts were quite pathetic
Answers for reference
b) 2.8 seconds