Investigating what effect the period of oscillation in a simple pendulum has.

Investigating What Effect The Period Of Oscillation In An Simple Pendulum

My aim in this investigation is to find out the acceleration due to the force of gravity. So in this investigation to achieve my aim I am going to experimentally determine a factor which effect the period (T) of a simple pendulum. This pendulum will consist of a bob hanging from a length of string.

Factors which affect the period (T) of a pendulum:

Gravitational Field strength
Mass of bob
Length
Angle of amplitude

We will be concentrating of the length factor and what affect it has on the period (T) of one oscillation. My prediction in this investigation is that the length of the string, where the bob hangs from will differ the period (T) of one oscillation. I.e. so the increasing of the length of the string will result for the increasing of Period (T).

To start of the experiment we had to raise the bob at a larger angle, than the point that it is vertically suspended at rest. By raising the bob the pendulum gains gravitational potential energy (GPE). As it is help above the point of natural suspension and so therefore is acting as the natural gravitational force. Once the pendulum is released the Gravitational potential energy turns into kinetic energy, which is needed for the pendulum to swing. Once the bob returns to the original point of suspension, the GPE has totally converted into KE, causing the bob to continue moving past the pivot point and up to a height equidistant from its pivot as its starting point. The same factor affects the pendulum on its reverse swing. The pendulum never looses any energy, it is simply converted from one form to another and back again.

I am therefore going to experimentally determine the relationship between the length and the period (T) it take for the pendulum to do one whole oscillation.

Method

I will firstly set up a clamp stand with a string attached to it 1.4 m long.
The bob will be held to one side at the angle of 5 degrees (measured with a protractor), and then released.
The stop clock will be used to take time of one full oscillation.
This will be done many times each time reducing the string by ...

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I am therefore going to experimentally determine the relationship between the length and the period (T) it take for the pendulum to do one whole oscillation.

Method

I will firstly set up a clamp stand with a string attached to it 1.4 m long.
The bob will be held to one side at the angle of 5 degrees (measured with a protractor), and then released.
The stop clock will be used to take time of one full oscillation.
This will be done many times each time reducing the string by 20 cm.
The length of the pendulum will be plotted against the period on a graph.

Apparatus

Meter ruler
Protractor
Stop clock
String
Clamp stand
Bob

Diagram

To make my experiment as fair as possible I will be taking the following steps:

The mass of the bob will be constant.
Angle of amplitude shall be a constant of 45 degrees. This will ensure that there are no variations acting on the forces acting on the pendulum.
The value of the gravitational field will be constant this will help me a lot to provide a fair test.
The intervals between the string will increase by 0.2 m providing a clear pattern in my result.
To ensure that the velocity is not affected, I will make sure that there are no obstructions to the swing of the pendulum.
A stop clock will be used to measure the period of time taken for 25 oscillations.

To make it a safe test I will be doing the following:

Making sure that the bob does not come in any contact with any thing.
The clamp will be put into a secure position so that it does not fall (which will demolish the experiment).
Excessively large swings will not be done as there is an angle of 5 degrees.

These are the results from my investigation. I had done two experiments exactly the same which resulted in:

My investigation was successful. The results from my table show that my predication was right. My prediction was as the lengths of the pendulum increases so will the period of the oscillation.

Obtaining Evidence

As I said in the method that I took the time for 25 oscillation, and I done it for 1 as well. I observed that each oscillation for the same length of the string seemed to be equal. This showed that the pendulum did not slow down as the number or oscillation increased.

I was carefully following what I had said in the planning on what I must do:

- The string was measured with a meter ruler to the nearest mm to ensure the exact difference of 20 cm.

- The angle was to be exact at my intended angle of 5 degrees.

- I used the stop clock accurately. It was reading to 2 decimal places but I then rounded it to the nearest decimal place.

Analysing evidence and concluding

Using the results from my table I drew a graph to show what had been obtained from the experiment. The graph clearly shows a positive gradient. This indicates that as the length of the pendulum is increased the period (T) will also increase. As you can see I had done two tests done with exactly the same procedure. The results also came out to become extremely similar. The graphs are almost identical. So I consider my proposed method to be reliable for this experiment. My findings indicate that the time period various directly with the length of the string when all of the other factor are constant.

Evaluating

My evidence obtained from my experiment supported my theory of: as the length of the pendulum increases so does the period (T) of one oscillation. My graphs show that the results came out in a straight line showing it was a continues result and had a pattern.

Factors which may have affected the accuracy of my experiment:

There could have been an error in the measurement of the angle. This was hard to do as the protractor was not in the exact place in al the experiments. Next time I would attach the protractor to the clamp so no adjustment could me made to the protractor.
The bob which was hanging from the string was made different in both experiment but with the same weight. In the moulding of this bob there could have been the error of making one bob more aerodynamic than the other, which would result in making the pendulum faster.
Another major error could have been on the human reaction time. The measurement of the period could have been inaccurate due to slow reaction on the stop clock.

Excluding the possible error my result came out to be reliable. So I can now say that my evidence is sufficient to support a firm conclusion that:

The only factor that affects the period of a simple pendulum is the length of what the pendulum is. As the length increases so does the time.

To extend my investigation and to find out more on this topic I will first of all do a lot more background research. I will set up the equipment much better and stable for example putting a G-Lock on the clamp and stick the protractor to the clamp. Also the main aspect I would like to look at is if I were to change the angle that I let the pendulum go at and the changing of the mass of the bob. I would be interesting to look at what would happen if the gravitational force wasn’t the 9.81 Newton’s, but was some thing different.

Physics

Navit Kundi

12PL