I chose these figures because I am not experienced in how to control lengths and weights, which is why some of the lengths are inconsistent.
Here are the preliminary results
Mass (g) Time Period of twenty swings (s)
1. 74.52 28.53
2. 69.32 28.47
3. 63.31 28.63
4. 57.7 28.53
5. 50.05 28.53
6. 45.01 28.23
7. 43.02 28.13
8. 41.5 28.13
9. 40.02 28.35
10. 36.5 28.43
Length Of String (cm) Time Period of twenty swings (s)
1. 103 39.13
2. 93 37.93
3. 84 36.63
4. 73 33.63
5. 63 30.73
6. 54 28.63
7. 44 26.63
8. 34 22.83
9. 24 19.05
10. 13 15.01
In my preliminary experiment, I forgot to vary the amplitude to find out if it affects the time period but I know from my own scientific knowledge that it does not. However, I also know from our own scientific knowledge that an only amplitude angle of 10 degrees or less will make the equation to find the time period work. This made me decide to set the angle at a constant 10 degrees. In the preliminary results I also did not realise to divide the time period of 20 swings by 20 for one time period, I also now know how to control the intervals and length of the string, so it is not so erratic.
From looking at the preliminary results, one can state the displacement and mass of the pendulum will have no effect on the final experiment results. This can also help to predict the final results:
“The longer the piece of string, the longer the time period of the pendulum”
This will happen because if the string is longer, it will have a longer distance to travel, so the time period will be longer. The longer the piece of strings the more potential energy, which will increase the velocity. From my own scientific knowledge I understand that the time period of a pendulum (T) equals two pi (2∏) times length in metres (L) over gravity (G).
If gravity is at a constant 9.81 N/Kg and the lengths our known, I should be able to do a prediction graph and table. If our experiment colludes with the graph, I will know it is accurate and was a valuable test, information I can use in my analysis and evaluation.
In our final experiment we will use 11 lengths from 110cm to 10 cm, using intervals of 10 cm. I will use a constant mass as the pendulum, and the displacement length will be 10 degrees. I chose these values because the lengths are spread out, to create a fair test. I will time 20 time periods to make it a fair test.
To help make it even fairer, I will repeat the experiment three times and take an average of the results.
For the prediction table, but not graph, it is helpful to note that as the equation works only in metres, the values, which would be in centimetres in my experiment, have been changed to metres.
Prediction table:
Length (m) Gravity (N/kg) Time period (seconds to 2 d.p.)
1. 1.10 9.81 0.71
2. 1.00 9.81 0.64
3. 0.9 9.81 0.58
4. 0.8 9.81 0.51
5. 0.7 9.81 0.45
6. 0.6 9.81 0.38
7. 0.5 9.81 0.32
8. 0.4 9.81 0.26
9. 0.3 9.81 0.19
10. 0.2 9.81 0.13
11. 0.1 9.81 0.06
