# An Investigation of the Factors affecting the Period of a Pendulum.

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Introduction

Awais Chouhdary. 11P2. Physics Coursework. Mr Thomas. Page of

G.C.S.E PHYSICS INVESTIGATION

By Awais Chouhdary. 11P2.

An Investigation of the Factors affecting the Period of a Pendulum.

In this investigation I am trying to find out what affect does length (l) have on the period (T) of a pendulum.

Variables which have an affect on the period of a pendulum are,

i) Length (of string) = l

ii) Amplitude = θ

iii) Gravity = g

iv) Air resistance

I will change only the length (l) of the string (Independent Variable) since that is what I am investigating. Length of the pendulum is defined as the distance from the point of suspension to the centre of gravity of the bob. I will keep all other factors such as Gravity (g), Mass of the bob and the Amplitude (θ) etc. (Controlled Variables) the same, for a fair test.

In my experiment, I will attach a Plumb bob with a piece of string and suspend it from a clamp stand through a split cork. The time taken for one Oscillation is defined as Period (T). One complete Oscillation or Vibration is to-and-fro the movement of pendulum. I will measure how much time (T) (Dependent Variable)

Middle

I think that according to my equation, if I draw a graph of length (l) against period (T) it will not be straight line and the length (l) will not be proportional to the period (T) but If I square root the length (l) and then plot it against period (T), the √l will be proportional to the period (T) thus I will get a straight line graph OR if I simplify the equation by squaring both sides (as shown below) and plot a graph of period-squared (T ) against length (l) , it will be straight line graph and the length (l) will be proportional to the Period-squared (T ).

T = 2π √l/g

Simplified by squaring both sides:

T = 4π l/g |

I have used A level books and books from library to explain the formula I was using and to help me rearrange it. The information helped me to plan my experiment and was also useful when I was explaining my prediction.

Apparatus

i) Plumb bob

ii) Metre Ruler

iii) String

iv) Clamp Stand

v) Split Cork

vi) Stop Watch

vii) Angle Measurer

Method

·Attach the string to the Plumb bob.

·Place the string between the split cork and place the cork in the jaws of Clamp stand.

Conclusion

The counting could become more accurate if it is possible to have some sort of electronic detection system that could automatically count and time the swings. Something like a light gate as part of a computer based logging system might work. An alternative might be a very high speed digital video camera that could accurately record the position of the bob and the elapsed time.

Further work can be done on the factors, affecting the period of a pendulum. for example, changing bobs of different masses or trying out the experiment at different gravity levels to see if it affected the acceleration of the pendulum. There is an alternative way that a pendulum can swing. Instead of swinging backwards and forwards in a single plane it is possible to make the pendulum swing in a horizontal circular path. It would be interesting to investigate how the time for each revolution of this 'conical pendulum' changes with the length and to compare this with the ordinary simple pendulum.

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This student written piece of work is one of many that can be found in our GCSE Forces and Motion section.

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