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Analysis:
The efficiency of an electric motor was shown to change significantly as its load is varied. The load used in the lab on the motor varied from 50.0g to 150g, increasing by increments of 25g. As the mass was increased, the efficiency of the motor decreased. The average efficiency of the motor at 50g was 18.48%, at 75g it was 9.44%, at 100g it was 7.5g, and at 150g it was 3.76%. Thus there was a 200% increase in the mass of the load, and a 79.7% decrease in efficiency, proving that increasing the load of the motor will result in a decrease of efficiency.
The loss of energy can be attributed to several factors. The force of friction acts as one factor. As the load increased more friction was placed upon the moving parts of the motor. This increase in friction required more energy be used to overcome friction than to turn the armature of the motor. The friction also creates heat, which releases energy into the environment and away from the motor. The loss of energy can also be due to an increase in the current flow sent through the wire. As the load increased, the motor required more power to lift the masses, and the increase in power is another source of error. To supply more power to lift the heavier load more current is needed to flow through the wire thus causing the voltage to decrease. This increased current caused the wires to heat up. This energy creating heat is lost to the environment. As the load continued to be increased, more heat was created, and thus less energy was used to power the motor. This caused the decrease in efficiency and the loss of energy in the motor.
Kinetic energy should be considered in this lab because for some of the trials it had a significant impact. The total work output was determined by adding the potential as well as the kinetic energy. In the 50g mass trials the kinetic energy was equivalent to over 5.0% of the potential energy. Kinetic energy was included in all of the calculations to eliminate this 5.0% error and to keep the lab consistent. Kinetic energy showed to have much less an impact in the other trials, as in the 150g trial where it accounted for less than a tenth of one percent of the potential energy.
The sources of error in this lab did not affect its outcome significantly, but are still important in discussing the validity of the lab. The first source of error was the 5.0g masses needed in 75g, and 125g mass trials. 5.0g masses were not available, forcing the group to estimate 5.0g with paperclips, which may not have been accurate. Another source of error was involved with the timing. Many of the trials happened so quickly that it was impossible to expect a human to obtain a precious measurement. To account for this error, three trials were taken for each mass, but the error could not be completely eradicated. Another source of error was due to the changing values of the voltage and amperage. The values fluctuated as the load was being lifted and the average value, based upon the reader’s discretion, was taken. Overall, the lab was valid as the sources of error had only small consequences on the total outcome of the results.
Conclusion: Our experiment proved our hypothesis which stated that the efficiency of the motor would increase as the load grew heavier incorrect. We observed the opposite, as the efficiency of the motor decreased as the load increased.
The efficiency of an electric motor was shown to change significantly as its load is varied. The load used in the lab on the motor varied from 50.0g to 150g, increasing by increments of 25g. As the mass was increased, the efficiency of the motor decreased. The average efficiency of the motor at 50g was 18.48%, at 75g it was 9.44%, at 100g it was 7.5g, and at 150g it was 3.76%. Thus there was a 200% increase in the mass of the load, and a 79.7% decrease in efficiency, proving that increasing the load of the motor will result in a decrease of efficiency.
The loss of energy can be attributed to several factors. The force of friction acts as one factor. As the load increased more friction was placed upon the moving parts of the motor. This increase in friction required more energy be used to overcome friction than to turn the armature of the motor. The friction also creates heat, which releases energy into the environment and away from the motor. The loss of energy can also be due to an increase in the current flow sent through the wire. As the load increased, the motor required more power to lift the masses, and the increase in power is another source of error. To supply more power to lift the heavier load more current is needed to flow through the wire thus causing the voltage to decrease. This increased current caused the wires to heat up. This energy creating heat is lost to the environment. As the load continued to be increased, more heat was created, and thus less energy was used to power the motor. This caused the decrease in efficiency and the loss of energy in the motor.
Kinetic energy should be considered in this lab because for some of the trials it had a significant impact. The total work output was determined by adding the potential as well as the kinetic energy. In the 50g mass trials the kinetic energy was equivalent to over 5.0% of the potential energy. Kinetic energy was included in all of the calculations to eliminate this 5.0% error and to keep the lab consistent. Kinetic energy showed to have much less an impact in the other trials, as in the 150g trial where it accounted for less than a tenth of one percent of the potential energy.
The sources of error in this lab did not affect its outcome significantly, but are still important in discussing the validity of the lab. The first source of error was the 5.0g masses needed in 75g, and 125g mass trials. 5.0g masses were not available, forcing the group to estimate 5.0g with paperclips, which may not have been accurate. Another source of error was involved with the timing. Many of the trials happened so quickly that it was impossible to expect a human to obtain a precious measurement. To account for this error, three trials were taken for each mass, but the error could not be completely eradicated. Another source of error was due to the changing values of the voltage and amperage. The values fluctuated as the load was being lifted and the average value, based upon the reader’s discretion, was taken. Overall, the lab was valid as the sources of error had only small consequences on the total outcome of the results.
Conclusion: Our experiment proved our hypothesis which stated that the efficiency of the motor would increase as the load grew heavier incorrect. We observed the opposite, as the efficiency of the motor decreased as the load increased.