September 20, 2011
A pendulum is a device which consists of a mass attached to a string from a frictionless pivot which allows it to swing back and forth. In this experiment, the time it takes for a pendulum to go through a period is going to be measured. The time it takes for a pendulum to go through one period can depend on factors such as the length of the string, mass, or the degree in which the pendulum is released from (amplitude). In this experiment, only different masses will be used in order to prove that mass does not have an effect on the time it takes for a pendulum to go through a period.
The purpose of this experiment is to determine the effect of mass on the period of a pendulum.
If the mass of the pendulum increases then the time for the swing will neither increase nor decrease because the mass does not have an effect on the period of a pendulum.
Materials and Methods
The materials used in this experiment are:
3 Different Masses (20g, 50g, 100g)
With these materials, the experiment was conducted in the following procedure:
1) Place the clamp to a flat surface with a string attached to it 2) Attach a 20g mass to the end of the string opposite from the pivot 3) Pull the mass to the side with an amplitude of 70º
4) Release the mass and allow it to swing 10 periods while timing it 5) Divide the total time by 10 in order to get the time it takes for 1 period of the pendulum 6) Repeat steps 2-5 with different masses (50g, 100g, 120g)
The results between the different masses were not all the same number however, they were close. The 20g mass period took 1.5 seconds and the 50g took 1.6 seconds. The 100g and 120g masses both took 1.7 seconds to complete a period.
Discussion and Conclusion
What was expected at the end of the experiment was for all of the times between the different masses to be the same however, this was not the case. The slight differences in time were most likely due to random and human error. During the experiment, a clock was used to time the periods in seconds. Using the clock falls under the random error category since the timing wasn’t precise as it would be if a stopwatch was used instead. The other error in this experiment would be a human error because the experiment had one person release the pendulum after the person timing gives the signal. The time between the signals are given and when the pendulum starts swinging could be off so in order to avoid this error in subsequent trials, the person timing the period should be the same person releasing the pendulum. Although the results between the 4 masses were different, they were only off by less than .3 seconds. The results showed that difference in mass does not have a significant effect on the pendulum period thus, making the hypothesis for this experiment true.
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