A Grade GCSE Physics Experiment— Investigation Into the Effect of Parachute Surface Area in Relation to Its Fall Time
I am going to investigate the effect of a parachutes surface area in relation to its fall time.
I predict that the larger the surface area of the parachute the greater amount of time it will take to reach the ground. This is because a larger surface area will have a bigger air resistance meaning that more air particles collide with the parachute as opposed to a smaller surface area. Similarly, when the surface area is reduced, the time taken for it to reach the ground decreases because fewer air particles collide with the parachute, i.e. there will be less air resistance. Also, although a parachute with a larger surface area would weigh more and therefore experience a greater downward force of gravity, it would still have much more air resistance and so, would still not fall faster than a smaller parachute.
Firstly I will cut out eight different sized parachutes from paper. The parachutes will be of radius 12cm, 11cm, 10cm, 9cm, 8cm, 7cm, 6cm and 5 cm. The sizes are evenly spaced because when I come to plot my results they will be easier to read and hopefully a pattern will appear.
I will then measure a height of 2 meters and make a mark on the wall on which I will drop each parachute from. I will drop each of the parachutes four times in total and with a stopwatch I will record the time taken for the parachute to reach the ground from the time when is dropped to the point when it hits the ground. I will take the average fall time from each parachute and record the results on a graph.
How a Parachute Is Made
A circle is cut out with the relevant radius. A solid line is drawn horizontally from the centre to the edge. A dotted line is then drawn 60o away from the solid line. The solid line is cut and rotated round to meet the dotted line where it is glued in place. A parachute shape is made. (See diagram 1)
The apparatus I will use in this investigation are as follows:
- Paper A5 – that can be cut into different sized circles
- Measuring tape
There is not much safety to consider in this experiment however, I will make sure this experiment is as safe as possible.
There are different variables which can be changed in this experiment. I am however, due to my line of inquiry, going to change the surface area of the parachutes. The variables I will control will be the height I drop the parachute from, the type of material I use for the parachute and the conditions of the environment, also the mass (i.e. I will not put any paper clips or clay on the parachutes.)
Below is a table showing the effect of changing variables. (Table 1)
To ensure the investigation is fair I will keep all the variables the same apart from the one I am changing. I will also try to carry out the investigation to the greatest degree of accuracy I can manage. This means that I will drop the parachute from the same height each time but the surface area will be altered each time. I will keep the air vents and windows closed as this will affect the rate at which the parachute falls. Although air resistance and gravity will affect the fall of the parachute, I cannot control these factors; however, it will be the same for each experiment so the results should be unbiased.
Below is a sample graph (graph 1) to show the kind of results I expect to obtain.
Below are the results I have obtained.
I can see, by observing the table that the larger the surface area of the parachute the greater amount of time it took to reach the ground. This means that the larger the surface area the more air particles (air resistance) hit the parachute. Similarly, the smaller the surface area of the parachute the less air resistance there was.
On the next two pages is a Bar Chart and scatters graph showing the results of the experiment—(draw a bar chart from the results you have obtained).
In conclusion, there is very strong evidence to show that the larger the surface area (radius) of the parachute the longer it will take to fall to the ground. This is because more air particles collide with the parachute when there is more surface area as opposed to a smaller surface area. Even though there is more gravity acting on the larger parachutes the smaller ones are more streamlined and also have less air resistance. These two factors, therefore, meant that they fell to the ground in a shorter time.
Diagram 1 illustrates that there was less air resistance because the surface area of the parachute is smaller than that the parachute in diagram 2 i.e. the parachute in diagram 1 is more streamlined and so fell more quickly as opposed to the other less streamlined parachute.
The evidence I have obtained shows that my prediction “the larger the surface area of the parachute the greater amount of time it will take to reach the ground” was correct. Also the graph I drew showing the results I expected matched the pattern of the actual results.
All of my results fitted my pattern of results. I did not have any problems when I was carrying out the experiment apart from with timing. There were a few times when I got extremely “bogus” times that were more than a 2 seconds out from the repeat times. I overcame this by timing the fall of the parachute again.
The quality of my evidence is good, there were no points on my scatter graph that were not on, or close to the line of best fit, There were also enough results to show that my prediction was correct. I only circled two anomalous results that were close to the line, but not as close as the other results.
All of the methods worked well apart from the timing. The timing was too difficult to make as accurate as possible as this would have cost money. I had to rely on my reactions as to when the parachute was dropped and when it landed. However, my reactions would have been similar on each of the parachutes.
I could have got a friend to time but the results would have turned out relatively similar. Another way I could have timed would be if I used some sort of machine that could have timed the fall of the parachute, but as afore mentioned it would have cost money and would not be readily available.
By comparing the repeated times on each of the parachutes I can see that they were similar and each one was within a tenth of a second of each respect. From this evidence, I think my results were pretty reliable.
Regarding the two anomalous results I circled on the scatter graph, they might not have been accurate because of the method of timing.
In order to provide additional evidence and extend my investigation to find out more and back up my conclusion, I could perhaps get a machine that would drop and time the fall of each parachute. I could also change the material and see if I get a similar pattern of results. I might consider changing the radius of the parachutes I already have and record the results. Another thing I could change is the height I drop the parachutes from and see if this effects the conclusion I have made, also the weight could affect my idea about air resistance.
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