Enter your results in table C.
Results:
Table B
Length of pendulum = 20cm, mass of bob constant.
Table C
Amplitude = 6cm, Mass of bob constant.
Discussion and questions:
-
Plot a graph of period (T) against length (L) and period against the square root of L. What do these graphs indicate about the relationship between period and length?
Working out
- What other factors (not investigated in this practical) may influence the period of a pendulum?
- The reaction time of the person working the stopwatch
- The technique used to determine the amplitude of the pendulum
- Wind produced by the fans
- What are the main sources of error in this practical?
- The reaction time of the person working the stopwatch
(Human error)
- The technique used to determine the amplitude of the pendulum
(Systematic error)
- Wind produced by the fans
(Random error)
- How could you improve the accuracy of your results?
The accuracy of the results of this experiment could be improved by ensuring that the same person controls the stopwatch at all times, so that the reaction time is always the same. Also, if there were some other means of investigating the oscillation of the pendulum, such as more accurate measuring by use of lasers, the experimental results could definitely be more accurate than is possible with human interpretation.
The environment in which the experiment is carried out in should also always stay the same. For instance, if the results are taken from an experiment which was conducted in a room where fans were operating, the results could definitely be inaccurate. In saying this, to improve the accuracy of the results in future, experiments should always be carried out somewhere where no environmental effects can play part.
Conclusion and Evaluation of Practical
How does the period of a pendulum depend on the amplitude of the swing and the length of the string?
In summary, this experiment determined that increasing the length of the pendulum also increased the period of one oscillation. The percentage difference between the experimental value, which was 11.67ms-² and the Theoretical value (9.8ms-²) was approximately 19.08%.
In this experiment, sources of Systematic and Random error that led to a significant percentage difference include could have influenced our results. Such as the reaction time of the person operating the stopwatch. If there were some other way of determining the oscillation of the pendulum, such as more accurate measuring by use of lasers, the experimental results could definitely be more accurate than is possible with human interpretation. If a machine that could calculate one correct oscillation of the pendulum using more complex and accurate technology was used for this experiment, human error could be greatly reduced and would give more accuracy to the end result.
Determining the amplitude of the pendulum and the method used could have also played the part of systematic error. The amplitude of the pendulum can affect the time to complete one oscillation. To ensure more accuracy in future experiments, a protractor could be used so the pendulum would be aligned to the exact amplitude.
Random errors such as wind produced by the fans may also have affected the results. Making sure all variables in the environment are stable by closing windows and switching off fans, will also reduce the uncertainty of the experiment.
These sources of error all affect the amplitude of the string, the length of the string, the oscillation and, overall, the end result. If more accurate measures of determining the desired information were used, more accuracy could be accounted for and the result would benefit.
