The speed of the wave is directly proportional to the wavelength.
Aim
To find out whether drop height, depth or both affect the speed of a wave.
Method
The first thing I will do is to collect my equipment. The equipment I will be using is:
- Tray 4. Ruler
- Water 5. Clamp stand
- Stop clock
Stacey Owen
Candidate no: 0126
Hampton Community College
I will set my equipment up like this:
I will fill the tray with 0.5cm of water, then I will lift it 0.5cm above the tray height. Then I will drop it and let the water go up and down tray twice. At the point it stops at the second time, I will stop the clock and record the time. I will then drop it at 1cm, 1.5cm, 2cm and 2.5cm. I will then refill the tray to 1cm and drop the tray at each height, I will refill it 0.5 cm higher after dropping it at each height until it reaches 2.5cm. I will then repeat the experiment again and get an average.
I predict that the drop height will not affect the speed of a wave that much. Whereas I think that the greater the depth of water the faster the waves will travel. The reason for this is that when the water is shallow the container bottom begins to interfere with the 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 the greater the force of the wave, which creates more momentum and speed.
Stacey Owen
Candidate no: 0126
Hampton Community College
Science Coursework
Waves
Results
I repeated my results; I will then obtain an average. I have also worked out the speeds.
I recorded the results and then put them into a table.
1st set of results
2nd set of results
If you look at these two sets of results, you can see that that drop height results goes across and the depths go down. If you look at the differences of the result that go across there is not much difference whereas if you look at the results which go down there is a lot more difference.
Stacey Owen
Candidate no: 0126
Hampton Community College
These are my average results.
Now I will work out my speeds. I can do this using the formula, speed=distance ÷ time taken. I let the wave go up and down twice. The tray is 38cm, 38*4=152. e.g. 152 ÷ 72 = 21.1.
These are the average speeds.
Stacey Owen
Candidate no: 0126
Hampton Community College
Science Coursework
Waves
Conclusion
I’ve found out my prediction was correct. I have drawn a graph which is average speeds plotted against depth.
There is a definite relationship between the two sets of data that I used to plot the graph. To conclude this, I can say that the depth of water affects the speed of a wave but the drop height does not. This is because when the depth and drop height is 0.5, the speed is 21.1 but when the drop height is 2.5 and the depth is 0.5, the speed is 24.5 which is not much difference. But when the drop height is 0.5 and the depth is 2.5, the speed is 52.4 and there is a lot more difference between 21.1 and 52.4 then there is between 21.1 and 24.5. So the more water, the quicker the wave is.
Stacey Owen
Candidate no: 0126
Hampton Community College
Science Coursework
Waves
Evaluation
The evidence, I obtained has helped me to come to my conclusion on the previous page. My results show quite definitely that as the depth increases, the speed increases. I’m happy with the accuracy of my results for two reasons:
- The results follow my prediction.
- All the points for each drop height line are close to the lines of best fit.
I could have made my experiment more accurate if I had taken more sets of readings, I would have obtained a better average.
I’m pretty pleased with the suitability of my experiment for the following reasons:
- I was able to get two good and valid sets of readings using the equipment and time allowed.
- I made sure that the test was as fair as possible by putting the water in then measuring one end, the middle and the other end of the tray when the water was put in there. Also if there was any spillage I would measure it and then fill it back to the right depth.
There was not any anomalous result; they were all very close together. Therefore I’m happy that my evidence is accurate and reliable enough to support my conclusion.
To improve and extend this investigation I could use the same method to investigate a greater range of input variables e.g.
- Temperature
- Liquids
- Distances
Stacey Owen
Candidate no: 0126
Hampton Community College