motor efficiency

The aim of this experiment is to compare the electrical energy used to operate a motor with the potential energy gained by a mass raised by the motor.

Materials:
1. 1 motor
2. String
3. 1 spool
4. Ammeter
5. Voltmeter
6. 7 insulated cables
7. Stand to hold the motor
8. 1 switch
9. 1 rheostat
10. 1 power pack
11. 3 x 10 gram weights

Procedures:
1. Set up a circuit as shown in figure 50-1.
2. Tie the cotton to the spool and attach the spool to the motor
3. Tie a ten gram weight onto the end of the cotton string
4. Dangle the weight over the side so it is just touching the ground
5. Turn the motor on and adjust the resistance using the rheostat to get the weight to a point where it is being lifted at a constant rate.
6. Measure the time it takes for the weight to reach the very top
7. Record the amps, volts and time it takes for each turn twice.
8. Repeat step 1 to 7 for the 20 and 30 gra...