For the second test, where we increase the weight by using more than one paper case I predict that the heavier the object is the quicker it will drop to the floor. This is because the downward force will be much stronger at the start as the extra weight applied. Therefore even as the air resistance equals out the paper cases will be moving at a quicker terminal velocity than they previously were with less weight.
Measurements
In order to make sure that my results are reliable I will repeat each test 3 times. This is so that any anomalous results do not change my average results as much. I will drop the case/cases at 8 different height intervals. This is so that I get a range of answers and I can easily analyse my results. The eight different heights will have a gap of 20 cm between each. The lowest drop will be from 50cm whilst the highest will be from 190cm. I have chosen these measurements after completing my preliminary results. This is the conclusion that I came to after completing the testing:
- Beginning at 10, 20, 30 or 40cm did not give enough time for the person operating the stop clock to get a reliable time.
- When using 10 cm gaps between each drop there was not a large enough spread in the results.
- When increasing the weight of the paper cases there was not enough difference in timing of the results when only one case was added each turn.
Apparatus
I will use the same equipment for each test this is to make sure that it’s a fair test.
The apparatus needed is:
- Paper cases
- Clamp
- Stand
- Stopwatch
- Metre stick
Method
- Assemble the apparatus. (as shown above)
- Drop the required number of paper cases from the specific height.
- Start the stopwatch as soon as cases are released.
- Stop the stopwatch as soon as the cases hit the floor.
- Record the results in my table.
- Repeat the height so you have 3 results for each height.
- Work out the average results.
If I follow this method then I should end up with reliable answers.
- No secondary source information was used in this investigation
Safety
In order to run a successful investigation I must be sure that there are no risks or hazards evident. In order to do this I have devised a safety list to ensure the experiments pass with no accidents:
- Coats and bags must be out of the way, preferably under the table.
- At no time should students run in the lab.
- Take care when handling the equipment, especially metre sticks and stands.
This is a relatively safe test though so no extreme measures need to be used.
Obtaining Evidence
I have now completed all my tests and have results for 1 paper case dropped at 8 different heights and 3,5,7 and 9 dropped at the same heights. After putting the results in tables I managed to work out averages for the results. This will improve my graphs as I will be able to add a line of best fit to the graphs.
1paper case
3paper cases
5 paper cases
7 paper cases
9 paper cases
I have rounded the averages to 2 decimal places so that the averages are easier to plot on graphs.
Analysis
I have now used the data from the tables and converted them into graphs this is just another way of presenting the data. I have also added a line of best fit to each graph.
1 Paper case
3 paper cases
5 paper cases
7 paper cases
9 paper cases
I have now grouped all the average results together and put them in a table and also presented them in a graph. This shows that there is definite positive correlation between the weight dropped from and the time taken to reach the floor. Also the positive correlation between the height the paper cases are dropped from and the time it takes for them to reach the floor.
Conclusion
From analysing my results I can prove that the heavier the weight the less time it takes for the cases to hit the floor. Also the higher the height which the case is dropped from the longer it takes to reach the floor. This supports my predictions as I had thought that the time would increase when the height was raised and would decrease when the weight is increased.
Evaluation
After completing my investigation I conclude that my results are accurate and reliable. I can say this as I repeated each test 3 times so as I got reliable accurate, results. Some average results though may not be exactly correct due to anomalous results. For example the 1st drop at 70 cm with 5 cases is almost 0.3 seconds slower than 5 cases dropped at 90 cm. Another example of anomalous results comes when 7 cases are dropped at 150 cm on the 3rd drop where it took 0.93 seconds to reach the floor compared with 0.56 and 0.66 with drops 1 and 2 respectively. The result from drop 3 is almost double that of drop 1 which suggests that there may have been a problem during the drop. The equipment which I have used is very reliable. I know this as I used the same equipment for each test. This is to make sure that I avoid getting different results due to the different equipment. I have also stuck with the same method to make sure that the results I get are reliable. In order to improve this investigation I think that by repeating the exercise more times per drop would give me a more accurate average which anomalous results don’t effect as much. Another improvement which would help me gain more accurate and reliable results would be if I used light sensors to record the time between when the paper cases are dropped and when they reach the floor. This would be more accurate than having someone timing with a stopwatch as the sensors will be able to get the exact time whereas humans are not able to continuously do this.