# Investigating Factors Which Affect The Period Time Of A Simple Pendulum

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Introduction

Investigating Factors Which Affect The Period Time Of A Simple Pendulum Planning Definitions: Oscillation: Repeated motion of pendulum (to and for) Period (T): Time taken for one full oscillation In this investigation, I am going to experimentally determine a factor which will affect the period of a simple pendulum and the mathematical relationship of this factor. This type of pendulum will consist of a mass hanging on a length of string. Factors, which affect the period (T) of a pendulum: - Length (L) of pendulum - Angle of amplitude - Gravitational field strength (g) - Mass of bob I predict that the period will be affected by the length of the pendulum. An increase in length will produce an increase in time. I based by prediction on the scientific theory I found in a physics textbook: The pendulum is able to work when the bob is raised to an angle larger than the point at which it is vertically suspended at rest. By raising the bob, the pendulum gains Gravitation Potential Energy or GPE, as in being raised, it is held above this point of natural suspension and so therefore is acting against the natural gravitational force. Once the bob is released, this gravitational force is able to act on it, thus moving it downwards towards its original hanging point. We can say therefore, that as it is released, the GPE is converted into Kinetic Energy (KE) needed for the pendulum to swing. Once the bob returns to its original point of suspension, the GPE has been totally converted into KE, causing the bob to continue moving past its pivot point and up to a height equidistant from its pivot as its starting point.

Middle

* The clamp stand will be firmly secured to the bench with a G-clamp so that the clamp stand will not move, affecting the results. Excessively large swings will be avoided (angle of amplitude will be 45 degrees Results of preliminary investigation My preliminary investigation was successful. I learned from my preliminary investigation that my proposed method might not give me sufficiently accurate results. These results may be inaccurate dueto a slight error of measurement in time, height or length.. I will take three readings of each value during my final experiment and take an average. I will also measure the time taken for 5 oscillations rather that 1 and then divide the result by 5. These two changes will hopefully help me to identify and eliminate anomalies, sshould they occur. They should also add to the accuracy of my results. Obtaining Evidence I used the method proposed in my plan, taking three readings of each value and measuring the time taken for 5 oscillations rather than for 1. During the experiment, I observed that each oscillation for the same length of string seemed to be equal. This showed that the pendulum did not slow down as the number of oscillations increased. I took the safety measures described in my original plan. During the experiment I was careful to use accurate measurements in order to obtain sufficiently accurate results, for example: - The string was measured with a meter ruler, to the nearest mm, to ensure that each measurement had a difference of exactly 10cm.

Conclusion

However, the majority of my results were no more than a decimal place away from the formula results and, therefore, quite reliable. Had there been any anomalous results, I would have repeated my readings. Factors which may have affected the accuracy of my results include: - Error in measurement of angle of altitude. This angle proved difficult to measure and it was hard to get the exact same angle for each result. To improve the accuracy of this measurement, I could have attached the protractor to the clamp stand so that it was in a fixed position. - Error in measurement of string. To improve the accuracy of this, I could have marked off the points with a pen to ensure they were as accurately measured as possible. - Human reaction time. Depending on human reaction time, the measurement period time could have been measured inaccurately, due to slow reactions when setting the stopwatch etc. This could have been improved by involving another person to aid me with my experiment, for a quicker reaction time. The procedure was relatively reliable, excluding human error, and so I can conclude that my evidence is sufficient to support a firm conclusion that: The only factor which affects the period of a simple pendulum is its length. As the length increases, so does the period. If I were to extend my investigation, I would investigate to provide additional evidence to back up my conclusion, for example, changing the mass or angle of altitude. The results gained would hopefully aid me further in supporting my Scientific Theory. It would also be interesting to investigate how the factors are affected when the Gravitational Field Strength is different, i.e.. not 9.8 Newton's.

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