Investigation of a simple pendulum and what effects it the time period?

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Investigation of a simple pendulum and what effects it the time period?

Simple pendulum

A simple pendulum consists of a mass suspended on a length of string, which is allowed to ‘freely’ swing. To complete one oscillation the mass must swing from one side to the other and back again. The time of each oscillation will be recorded.

Diagram

There are several possible variables, which could affect the results of the time period.

  • Weight of the mass
  • Length of string
  • Point of displacement
  • Differing the shape of the mass
  • Thickness of string

 

Chosen variable

I have chosen to vary the length of the string as the variable. This is because it appears in the formula for the time period of one oscillation therefore it must affect the time period. Also there are no practical problems as there would be with varying the shape of the mass. This would be almost impossible to come to any clear conclusion as the way different shapes affect the time period, as there would be no clear mathematical formula that could be used. There is an infinite number of ways in which a shape can be changed, and coming to a clear conclusion about the way in which the time period would be impossible.

Furthermore, varying the length of string and timing the oscillations only requires simple equipment (a ruler and a stop watch) which minimises the margin of error, bringing the investigation to a clear conclusion.

Aims

I aim to find out how the length of string will affect the time period.

Prediction

As I increase the length of string I expect the time period to increase in a disproportional way as the formula contains powers and due to this fact I would expect the range between each result to be getting smaller.

Fair test

        To make this experiment a fair test I have made sure that no changes to any of the equipment will be made while conducting this investigation. I will only change the chosen variable (length of string). I will measure the length of string from the same point when altering each time I alter its length. There will be equal intervals in the result table. To reduce error I will record the time taken for ten oscillations to occur strung together as one complete time. I will repeat each different length three times to see if there are any extreme results which may affect the accuracy. From the three results I will find the average for one oscillation (by adding the three results together and then dividing by 30)

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Preliminary results

 

According to scientific theory, the relationship between varying the length of string and the time period should be:

Using the formula I can predict that (results are recorded in seconds):

  • 20cm of string will be = 0.88
  • 40cm of string will be = 1.26
  • 60cm of string will be = 1.54
  • 80cm of string will be = 1.78
  • 100cm of string will be = 1.99

These results do not correlate with my practical preliminary results. I believe that gravity was not given to an ...

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