# In this Coursework, we were given the task of investigating some factors which affect the period of a simple pendulum.

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Introduction

PLAN INTRODUCTION: A pendulum is a device which consists of an object suspended from a fixed point that swings back and forth under the influence of gravity. This effect is known as gravitation. However simple it may seem, this structure is very beneficial in our everyday life for it is used in several kinds of mechanical devices such as the all popular grandfather clocks. In addition to this, a pendulum could determine the local acceleration of gravity. This is the case, as the strength of gravity varies at different latitudes and as gravity is one of the main forces acting on the pendulum, the acceleration of gravity could be noted. Further uses of the pendulum are found in the field of astronomy for some have been used to record the irregular rotation of the earth as well as to detect earthquakes and others are used to demonstrate the rotation of the earth. The pendulum and its applications were first discovered by Italian physicist and astronomer Galileo, who established that the period for the back-and-forth oscillation of a pendulum of a given length remains the same, no matter how large its arc, or amplitude. (If the amplitude is too large, however, the period of the pendulum is dependent on the amplitude.) This phenomenon is called isochronism. A pendulum can be seen as a device whose energy is continually changing. When the pendulum swings to & fro, its energy changes from gravitational potential energy to kinetic energy and so on. This diagram of a simple pendulum clarifies this: AIM: In this Coursework, we were given the task of investigating some factors which affect the period of a simple pendulum. A period, is one complete oscillation. Possible factors that effect the period of a pendulum are: 1- Mass of object suspended 2- Length of string 3- Angle. However, due to limitations of time, and the complexity of carrying out some of the factors mentioned above, I will only look at 2 of the factors to investigate. ...read more.

Middle

not drawn the line of best fit on any of my graphs, so I could compare my results to the linear results) 1- VARYING THE LENGTH It is evident from the results that I have achieved, and the graphs that I have drawn, that there is a very strong relationship between the period of one swing, and the length of the string. This relationship shows to be a positive one. i.e. As the length of the string increases, the period increases, for we find that at 0.1m (the smallest length of string used) the period is 0.65s and the period increases as the length increases, until the period reaches its maximum of 1.99s when the length is 1m (the longest length of string). This proves my first prediction right, which states that as the length increases, the period increase. This is justified in allot of detail on page x. Basically, the reason for the period to increase as the length increases, because an increase in length, leads to an increase in the arc (the distance the suspended object has to travel through). When the distance increases, the time taken for the bob will undoubtedly increase, leading to an increase in the period. My second hypotheses for this experiment, refers to a proportional relationship between period squared and length. So not only am I looking for a general relationship between period and length, I am looking for a proportional relationship between them. A proportional relationship means that in doubling or tripling one factor (such as period squared) the other factor triples as well. I will test if this proportionality is true for period squared and length: 0.1m = 0.42s The figures above show that when the length of string is 0.1m, the period is 0.42s. When I double 0.1m, my period should also double. My results show: 0.2m = 0.81s The above shows that when I doubled the length of string to 0.2m, the period increased to 0.81s. ...read more.

Conclusion

I calculated the average percentage error for this experiment to be 2.5%. The practical difficulties I experienced in this experiment, were the same as the one experienced for the former experiment. However, there were more practical difficculties that I encountered, and this is why my average % error for this experiment were larger than the former experiment. They were: 1- It was very difficult to line up the pendulum with the angle required. I found it difficcult to get it exactly at the angle I want. Therefore my angles were adjusted to the nearest degree or two. 2- Notice that my actual line on the graph was always less than the linear line. This is because the pendulum could not be kept constant at the angle I wanted, and instead decreased by the time 10 complete oscillations occurred. It decreased because of air resistance acting on it. Again, I was under constraints of time when I carried out this experiment and now that I have completed it, I can provide possible solutions to the two above mentioned problems: 1- For the first problem, I can produce an enlarged protractor. This will make it easier for me to line up my pendulum with the angle I require. 2- For the second problem, I suggest that this experiment be carried out in a vaccum, where air resistance will have no influence on this system. To further this experiment, I will like to investigate the effect of other factors on the period of the simple pendulum. The factors which I wil like to experiment on are: 1- Mass of bob 2- Surface area of bob. This is as far as the simple pendulum is cocerned. However, I will also like to learn more about other types of pendulums, and factors which affect their oscillation and period such as the Bifilar pendulum which is used to record the irregalar rotation of the earth and the Foucault pendulum which is used to demenstrate the rotation of the earth. ...read more.

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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