2) I will hold the end of the container firmly and lift it to a height of 5cm, which will be measured using the ruler.
3) I will drop the container.
4) Using the stopwatch, I will measure the time taken for the wave to
complete three laps of the container.
5) I will repeat this experiment with depths of 0.2cm, 0.5cm, 1cm, 2cm,
3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm and 10cm.
6) I will repeat the complete experiment ten times to verify my results.
To make the experiment fair I will only change the depth of water, all other variables such as the size of container used, which would corrupt my results, will stay the same. I shall also make my results fair by doing accurate time keeping and making sure that the container is dropped from the same height each time. For each drop I shall make sure that I stop the stopwatch when wave has. For safety reasons I will make sure that the container does not fall on my hands. I will repeat the experiment ten times to make sure that my results are conclusive and any anomalous results are noticed easily. It will also allow me to find an average for my results.
Conclusion
As I predicted, the greater the depth of water, the faster the waves travel. This is can be seen clearly in my results as the depths of 2cm, 3cm and 4cm which recorded times of 3.45s, 2.95s and 2.67s respectively. It can also be seen when looking at the difference between the times recorded by the lowest and highest depths, which is 5.98 seconds. The reason for this is that when the water is shallow, the container bottom begins to interfere with water motion. The bottom constrains the water motion and results in a dragging affect on the waves. Also, the deeper the water the greater the mass and therefore force of the wave, which creates more momentum and speed. My results support this explanation totally.
Evaluation
The experiment itself was successful, I know this because the results found were what I would have expected and followed a strong pattern. For the same reason I think that if I repeated the experiment I would find the results would follow the same pattern, and the times would be extremely similar. The experiment was relatively accurate, however it was impossible to say exactly when the wave had reached the edge of the container. It was also hard to measure precisely 5cm from the table to the container when dropping, as my hand was prone to moving before the container was released. I was very careful to make sure that the depth of water was as accurate as the apparatus allowed and stopped the stopwatch, as close to the moment when the wave competed it’s final lap as I could.
I did observe one anomalous result, attempt 9 at a depth of 8cm when the wave was timed taking 1.80 seconds. This was not consistent with the other results taken for that depth and so was re-timed, giving a more likely time of 1.69 seconds. The anomalous result was most likely due to either the stopwatch being started before the container had been dropped, or the container being dropped at the wrong height.
Yet I did observe the results I expected, had only one anomalous result and followed the rules of my plan making it as fair a test as possible. My investigation was conducted safely and without any setbacks. I therefore, considering the above, believe my experiment was fairly accurate but could be improved upon by considering the previous points.
To expand and improve upon my investigation I could: -
· Wedge a level object under the container and remove it from underneath to drop the container. This would determine that the dropping height remained constant.
· Use a wider range of depths.
· Use more accurate apparatus for measuring time and distance.
All of these would enable me to make more detailed and accurate conclusions.
Ultimately I think my initial plan was suitable, giving the time and apparatus available to me, but could be improved or expanded upon by considering all of the above.
Planning
Aim:
The aim of this experiment is to gain results by dropping a water container from different heights (amplitude) to see which height can get the fastest wave.
Method:
As the container is dropped I will start the stopwatch. Then as the waves in rebounding back onto the side it started on I will stop it and record this time. I am going to do these three times to gain an average of the results. To calculate the speed I am going to do this equation:
Speed = distance/time taken
That is how I am going to be able to calculate the speed of the wave.
Variables
There are many other things that can make the speed of the wave differ. I will explain them all. First there is the depth of the water; this will change the speed because it will affect how much water the wave is going to have to carry as it travels the distance across the container. Less water will increase the speed and the more water will slow the wave.
Amplitude is another factor, which might change the speed of the wave, if the container is dropped from another height for example a very high drop obviously the wave is going to have much more momentum.
Prediction
My prediction is that if I change the amplitude I wont get much of a change in the speed of the wave. I predict this because I have thought about it and have worked out that it can’t change. So I predict that by changing the depth of the water in 10-ml intervals I will get more accurate, helpful, results. I will find out if I am right after I have concluded my preliminary work.
Apparatus
Water container
Ruler
Water
Pencil
Paper
Measuring cylinder
Results
The results I’ve gained I’ve put into a table, which I show below.
ANALYSIS
When my graph is looked at its clear to see that the gradient of the line doesn’t show any particular increase in gradient. This is because the results I got were similar and so it couldn’t change much.
If I was needed to have to talk about how my results faired at the end of the experiment I think that they are very good. I managed to find out after the practical that when the variable changed is the amplitude, it doesn’t change the speed of the wave at all. So by understanding that I can conclude that my results are very accurate. The only problem I had was the anomalous result. I was worried about this result, so I did it again, and I got 2.3 this seemed to be a reasonable value in comparison with the other results.
I personally think that the results I gained where correct and I am very happy with the way that the experiment went. The graph shows a smooth curve, which suggest to me, and anyone reading it, that my prediction was very incorrect. I predicted that if I changed the height at which I dropped the container it would change the speed considerably but it didn’t so I was wrong.
My conclusion to this experiment would be that the experiment I did didn’t really help us to find out the difference in the speeds of waves. So to help us gather better results for this purpose I would suggest another different experiment. I would suggest changing the height of the water. Instead I believe that this would gain much better results. If I had done this experiment I expect that I would have gathered a lot more about the differences in the speed of waves.
