Fair Test
I will make this experiment a fair test because the only variable I am controlling is the size of the paper. By using the same stopwatch throughout the experiment, I will be ensuring valid results every time. I will also use the same piece of paper because if I used a different piece of paper then it may have a slight difference such as mass or surface area, which would result in different results.
Results
Analysis
My prediction was right. From my graph, I can see that as the size of the paper decreases, the time taken for the paper to reach the ground also decreases. This is because, as I said in my prediction, when the size of the paper decreases, there is less surface area exposed to wind resistance and Upthrust, therefore the time taken for the paper to fall to the ground is decreased also.
Evaluation
Although in my experiment, I have no anomalous results, the results I recorded are not as accurate as possible. This is partly due to the stopwatch. It could have been more accurate because we recorded to 2 decimal places, but if we recorded to 3 decimal places, our results would have been more accurate. If I did the experiment again, I would make it better by using more accurate equipment such as a computer controlled stopwatch that would give precise results every time. I could extend this investigation by raising the height of where I release the paper from and see what effect this would have on the speed of an object.
Apparatus List
1000ml plastic tube
50 cm of thread
2g of plasticine
Scales
Stopwatch
Preliminary work
Before my main experiment, I decided to do some practices to determine how much plasticine to use and also how much water to use. I started by half filling the plastic tube with water and using 5g of plasticine. I found that the time it took for the plasticine to reach the bottom was far too quick for me too take a reading in. So, I increased the amount of water, by filling the tube to the top. I then dropped the plasticine again. I still found that the reading was too quick so I decreased the amount of plasticine I used. I now used 2g of plasticine and found that the reading I took was much easier and more accurate because I was not delaying. I had another problem which was that every time I dropped the plasticine in the water, I found it hard to get it out, so I attached a piece of string to it and solved this problem.
Plan
Experiment 2: Fill a 1000ml tube to 5cm from the top. Then measure from the bottom of the tube to the top of the water. Using accurate scales, measure 2g of plasticine. Attach a piece of string to the plasticine. Mould the plasticine into a torpedo shape and measure the diameter. Place the plasticine above the water and when released start the stopwatch. Stop when the plasticine reaches the bottom. Do not release the thread when dropping the plasticine. Hold the very end of the plasticine. Now repeat this three times. Record the results in a table and calculate the average. Then change the shape of the plasticine by making it into a flatter shape such as a cylinder. Repeat the above as many times as possible.
Prediction
I predict that as the shape of the plasticine becomes flatter, the time taken for the plasticine to reach the bottom will increase. I think this because when the plasticine is a torpedo shape, the water resistance will be smaller than if the plasticine was a cube shape. Therefore, if the water resistance is less, the time taken for the plasticine to reach the bottom will also be less. Also when the plasticine is a torpedo shape there is less Upthrust acting upon it if the plasticine was a cube shape. This will also result in a quicker time for the torpedo.
Fair Test
I will make this experiment a fair test because the only variable I am controlling is the shape of the plasticine. By using the same stopwatch throughout the experiment, I will be ensuring valid results every time. I will also use the same piece of plasticine because if I used a different piece of plasticine then it may have a slight difference such as density, which would result in void results.
Results
In my experiment, the height of water I used was 39.15cm.
39.15cm = 0.3915m
Analysis
My prediction was right. From my graph I can see that as the shape of the plasticine becomes flatter, the time taken for it to reach the bottom of the water also decreases. This is because, as I said in my prediction, when the plasticine is a torpedo shape, the water resistance will be smaller than if the plasticine was a cube shape. Therefore, if the water resistance is less, the time taken for the plasticine to reach the bottom will also be less. Also when the plasticine is a torpedo shape there is less Upthrust acting upon it if the plasticine was a cube shape. This will also result in a quicker time for the torpedo.
Evaluation
Although in my experiment, I have no anomalous results, the results I recorded are not as accurate as possible. This is partly due to the stopwatch. It could have been more accurate because we recorded to 2 decimal places, but if we recorded to 3 decimal places, our results would have been more accurate. If I did the experiment again, I would make it better by using more accurate equipment such as a computer controlled stopwatch that would give precise results every time. I could extend this investigation by raising the height from which I dropped the plasticine from and also by using a different liquid instead of water such as a soft drink.
