This blog post shares an IB physics lab report example about the period of a simple pendulum. Students can use this physics lab report example in order to figure out the format of a physics lab report. This physics lab report example includes all the steps that you should follow in order to come up with a well-structured ib physics lab report.
Oscillation of a pendulum is a result of acceleration due to the gravity. It is an example of simple harmonic motion and it occurs as a result of swing a bob of the pendulum; the bob goes forth and back. When the bob comes back to its starting point, it completes one oscillation. Time taken to complete 1 oscillation is called as period and it depends on some factors which are length of the pendulum, mass of the bob that is hanged from the pendulum, and material of the bob.
How does the length of pendulum which is ranged between 10cm and 50cm affect the period of a simple pendulum that is detected by taking time for 10 oscillations and calculating 1 oscillation time?
The aim of this investigation is to find the relation between the length of the pendulum and period of a simple pendulum
In this experiment, the effect of change in length of the pendulum on period of a simple pendulum is investigated. Therefore, the length of the pendulum is changed and it is arranged as 10cm, 20cm, 30cm, 40cm and 50cm and the lengths are measured by using a ruler with the length of 100cm.
In this investigation, the dependent variable is the period of 10 oscillations. It is measured by using stop watch. Average of the 5 trials for each length is measured and time for 1 oscillation is calculated by dividing the average result into 10.
There are some other factors that affect the period of simple pendulum. In order to investigate effect of only length of the pendulum on the period of simple pendulum, all the other factors are kept constant throughout the experiment. The mass that is hanged from the pendulum is constant and 250g for each trial. Also, the material of the masses that are hanged from the pendulum is iron for each.
As the length of pendulum increases, it is expected for the bob to take more time to complete its one oscillation, thus the period of one simple oscillation is expected to increase as well. Apparatus
- Stand and clamp
- Masses of 50g, 20g, 10g
- Ruler with the graduation of 1mm and length of 100cm
- Stop watch
- Board marker
- Clamp is hold on the top of the stand.
- The rope is fold in two. The side of the rope which the rope is fold from is tied in a way that the hook can be hanged from it. The ends of the rope are joined together on the clamp.
- The pendulous section of the rope is measured and regulated from the top to 10 cm. In that arrangement, ends are tied on the clamp.
- With the help of the ruler, 15cm from the bottom of the stand to right side is measured.
- That point is marked with a board marker.
- The mass of the hook is measured as 20g. By using the masses of 10g, 20g, 50g, 230g is added on to the hook to make the total mass hanged from the rope as 250g.
- The hook is hanged from the rope.
- The ruler is put on the marked point vertically to standardize the starting point of the oscillation, so to standardize the angle of release to omit its effect on period of oscillation.
- The oscillation of the hook is started from the ruler and when the oscillation is started stop watch is also started.
- When the hook completes 10 oscillations, the stop watch is stopped; time on the stop watch is recorded.
- 5 trials are taken.
- By following the same steps, the experiment is repeated with 20cm, 30cm, 40cm and 50cm of rope that is hanged from the clamp.
- For each length, 5 trials are taken and data is recorded.
DATA COLLECTION & PROCESSING
|Time Taken to Complete 10 Periods/ s /± 0.19 s|
|Length of the rope/cm/ ±0.05cm||Trial 1||Trial 2||Trial 3||Trial 4||Trial 5|
Table 1: Length of the rope and time taken to complete 10 periods
Uncertanity in time is calculated by the addition of reaction time to uncertainty of stop watch. (0.18+0.01= 0.19)
Here are the averages of time of the trials for each length; averages of the trials are calculated by the formula;
Investigation carried out with 10cm rope: = 9.44 + 0.03
Investigation carried out with 20cm rope: = 11.37s
Investigation carried out with 30cm rope: = 12.96s
Investigation carried out with 40cm rope: = 14.38s
Investigation carried out with 50cm rope: = 15.76s
The period for one oscillation is calculated by the division of average of trials of 10 periods into 10. Here are the time periods for one simple pendulum for each rope length;
Period of one simple pendulum with 10cm rope: 9.44 / 10 = 0.94s
Period of one simple pendulum with 20cm rope: 11.37 / 10 = 1.14s
Period of one simple pendulum with 30cm rope: 12.96 / 10 = 1.30s
Period of one simple pendulum with 40cm rope: 14.38 / 10 = 1.44s
Period of one simple pendulum with 50cm rope: 15.76 / 10 = 1.58s
CONCLUSION & EVALUATION:
The periods of one simple oscillation are found as 0.94, 1.14, 1.30, 1.44, and 1.58 for the rope lengths of 10cm, 20cm, 30cm, 40cm and 50cm respectively. The trend in results found in this experiment supports my hypothesis.
Scientifically, period of one simple pendulum is calculated with the formula;
In the formula; “L” represents the length of the rope in meters, and “g” represents the acceleration due to gravity.
By using this formula, the expected results for period of one simple pendulum with the lengths of 10cm, 20cm, 30cm, 40cm and 50cm can be calculated. Here are the real results;
T1= 2π= 0.63s
Scientifically, as the length of the pendulum increases, the period of one simple pendulum is expected to increase, too. Therefore, besides supporting the hypothesis, trend in results is scientifically true as well. However, the results found in the investigation are not exactly the same with the results found with the calculations by using scientific formula. For finding slightly different results, errors stated below that might appear in the experiment might be some of the factors. To overcome those errors, some precautions, which are stated below as well, should be taken to minimize the difference between the results.
Firstly, even the hook with iron masses is released to oscillate by the same person, the force applied to it for its first motion could have been different, and thus it leads to difference in results with the expected ones. In order to overcome this problem, the hook would be immobilized into a system with spring, and it would be released by the same force applied by the spring.
Secondly, the wind inside the experiment environment could have affected the time for completing one oscillation. In order to minimize the effect of wind blowing in different rates, two high wooden blocks can be put nearside the stand approximately 20 cm away from each side of the stand.
Also, the random error in measuring time by stop watch could have occurred. In order to minimize it, the investigation can be carried out by using “photogate”, which is much accurate in measuring time, instead of stop watch to measure the time.
Besides, another reason for difference in results could have been because of the mistakes made in timing 10 oscillations. The timing could have been ended when 10 oscillations are not over yet. Usage of photogate to measure the period of one pendulum would overcome this problem as well.
Lastly, to minimize the effect of errors in the experiment, the investigation should be repeated more and average of the trials should be taken.