Safety precautions
There are no obvious safety precautions to take in this experiment but care has to be taken when using the weights.
The reading I will be taking
The reading I will be taking is the weight attached to the string and the time it takes for 10 oscillations. I will be taking only one measurement and that is of the length of the string that will not be changed throughout the experiment, but because I am repeating the test I will be calculating the average from the two tests and finally from the averages I will be calculating how long it takes for one oscillation in seconds and recording that as well. The reason why I’m finding10 oscillations first is because it is hard to time 1 oscillation with an ordinary timer.
The test will be done twice for two reasons; one is to confirm that the experiment didn’t have any major errors and the second reason is that a rough average can be calculated from the two results.
With the results of this test I will be making a graph. This graph will be comparing the weight attached to the pendulum to the average time it has taken to do one oscillation.
The table I will be using for this experiment is shown below
The results should show according to my prediction that as the weight attached the period of oscillation should stay the same. So in theory all the results should be around the same time.
The complete range of results
Bellow is the graph I made showing the weight attached when compared to the average time taken for one oscillation
What the graph shows and what I can conclude from it.
Now as you can see the line of best fit is spoiled in this graph. This is because really this graph is looking too closely so the graph seem like there is no real correlation to the graph. When you look at the graph the range is only from 1.13 to 1.16 that is pretty small margin of error and also you have to consider that we were using a manual stopwatch so we have to account for human error.
I can conclude from this that the graph is looking too closely which only makes it look like there is no correlation to the bob and the time it takes for one oscillation. While really there is a strong relation
So when I look back at my prediction I can honestly say that my prediction was correct which was that the all the results would be similar and as the graph show the results are.
Evaluation of the experiment
On the whole the experiment was a success and it does show that the weight attached to the string has no effect on the period of oscillation. The method was fairly accurate but I would have preferred if I could have had a more accurate way of measuring the string and timing the pendulum. My prediction was correct thanks to the work of Galileo, which has proven to be quite helpful. Unfortunately the graph makes it look like the whole table is wrong but this is only because as previously stated was due to the fact that the graph was looking to closely at the results and if we were to do more tests and used a graph to larger scale you would see that there is a correlation in my results.
Improvement of the method
If I could I could redo the experiment and had more time and any equipment at my disposable I would have like to have an electronic timer of some sort that didn’t require a human to stop or start for 10 oscillations or even eradicate the need of doing 10 oscillations and jut do one. Also I would have like if we had used weights that were the same volume each time because in our experiment we were adding weights that increased in volume that decreased the length of string in the experiment. I think might have made some error to the result but probably not by much. Another thing I would like to do is to get more results with a more detailed range like for example rather than going up in 100 grams like I did this experiment I could go up in 50 grams instead.
THE SECOND EXPERIMENT
Method
In the second experiment we are looking at on how the length of string will affect the speed of oscillation. To conduct this experiment I will be tying a piece of string on top of a stand with help from a clamp at a certain length and at the bottom of the rope is a metal ball. The pendulum is released at a 45-degree angle and is timed for 10 oscillations then recorded and then the same test is repeated to check for errors and also from the two results an average can be taken. Once the experiment is done the string is extended and then the process starts again.
Equipment
The equipment we will need for this experiment will include…
1 bob
1 stand
1 clamp
1 Meter ruler
1 timer
1 80cm of string approximately
1 protractor
The same safety precautions will be maintained which was implied with the first, which was just to be careful with the weights.
Prediction
My perdition is that as the string is extended the period of oscillation. This is because of the longer string further the pendulum will have to travel further to make one oscillation. I believe this to be true because the as Galileo pointed out that the pendulum is not dependent on the weight attached or size of the pendulum’s ark, but on the length of the rod or string.
Fair Test
To make his a fair test I will be using the same bob through out the test and I will be releasing the pendulum at the same angle each time. Now I know that doing so is useless but also to make it a fair test I will be not changing the surrounding of where the pendulum experiment is done. Now this may seem a bit extreme but I might as well write it in because the place were the pendulum is does effect how the results come out. For example, this period will be greater on a mountain than at sea level.
Number of readings
Now all the reading will be the same as the first experiment in that I will be calculating how long it takes for 10 oscillations in sec for test 1 and test 2, the average time for 10 oscillations in sec and finally the period for 1 oscillation based on the average in seconds. The only difference is that in place the weigh attached in each experiment I will be showing in its place the length of the string in centimetres
This is the table I will be filling for the experiment.
In this table the experiment should show that the increases of the length of string should lead to the decreases in the period in oscillation.
As I predicted the period of oscillation increases the longer the string is this can be shown on a graph
Explanation of results and what I can conclude from it.
The experiment in general was very successful it because it shows that there is a relation to the length of string to the period of oscillation and that it shows that my theory was correct. The method that I use was fairly accurate but, the accuracy of the result is flawed because we have to account for that the stop watch was done manually and so we have to factor in human reaction time and that we couldn’t measure the string that well because we had to tie it from the top of the clamp which made it hard to measure when it was hanging freely from the clamp with a meter ruler.
Any unusual results
In this experiment there is not any really unusual results at all. None results that really sway off the line of best fit. The only reason I can give for the results that slightly sway off the line of best fit is because of human error.
What improvement would I have liked to make to the method if given the chance.
To get more reliable result I would like to have an electronic stopwatch that could stop and start automatically to reduce human error. Also I would have preferred if I could find a better way of increasing the string length and also a more accurate way of measuring the string because it was hard to make the string accurately. Also I would prefer if I could increase the string length in 5cm or less rather than in 10cm to get a more wider range of results also repeating the test a couple of more time would have helped as well because that way I could have made more accurate averages.
Bibliography
Original information that I previously know about pendulums I read from the book called Fatal Forces from the series called Horrible Science, which was written by Nick Arnold. The animation was found on Microsoft Encarta Standard edition 2002.