A multimeter is used to measure the efficiency of using a low speed electric motor to pull up an object. The motor was purchased from Scientifics Direct Inc. for about $25. Below is a sample calculation based on an 80 gram mass lifted 74 centimeters using 13 volts and 0.005 amps over a period of 33 seconds.
Work = (0.080 kilograms) x (9.8 meters per second squared) x (0.74 meters) = 0.58 Joules
Energy Consumed = (13 volts) x (0.005 amps) x (33 seconds) = 2.1 Joules
Efficiency = 0.58 / 2.1 = 0.28 = 30%
If you want to avoid using the acceleration due to gravity constant, you may choose to simply calculate the Joules per gram:
2.1 Joules / 80 grams = 0.03 Joules per gram
For more like this you can visit my blog at entropyrider.comThe write-up for this activity is provided in this lab manual for environmental science: