Name:         Akash Dubey                                        Date:        3/9/21        SIA Class Period: ½ B

Parachutes and Air Resistance Experiment

1. List Materials:

(suggested materials include a plastic bag, paper, string/floss, tape, ruler, coins/masses/plastic figures, timer/video)

        Plastic bag

        Yarn

        Packaging Tape

        Ruler

        Green figure with a loop on his head

        Video

2. What variable will you change?  What is your hypothesis?

I will change the size of the parachute. I hypothesize that the larger parachute will slow the figure down more if it can open properly.

3. How will you make 3 levels or versions of the parachute in order to test how this variable affects parachute descent?

I will create 3 different versions by changing the bag’s area. I will get 3 similar plastic bags and then cut them into a suitable size. Ideally, I want the areas of the parachutes to increase at a set interval like 5 cm^2

4. What dependent variables will you measure/observe?  Explain how you will accomplish each.

I will measure the amount of time that it takes for the parachute to reach the ground from a set height. I will probably try to hold it up as high as I can and then drop it. I will record it using a camera and then look at the video after the camera is done recording to see when it fell.

5. Describe your process to design each model parachute:

(The basic plan should be a parachute with a mass attached to string or tape.)

1. First I will gather all my above-mentioned materials and cut the bag into the size I want. (It will be shaped like a square) Then I will cut 4 strings of around a foot-long yarn.
2. With my bag laid out on the ground, I will attach all four strings using tape around an inch from the corner.
3. With all of the strings attached, I will pull them together and grab my figure. Then I will tie a knot through the figure’s loop and then I am done!
4. This will be a quality test to make sure the parachute is strong: Finally, I will grab the figure and do a test drop to see if everything works.

6. Describe your experimental procedure:

Create one parachute

Start the video camera

Hold the parachute as high as I can

Then gesture to the camera that I am about to drop the parachute

Then drop it

And then repeat these steps for as many trials as I need

For the next version, I will cut a different bag to the size I want and simply remove the bag on the original parachute and attach it to the new one

Repeat the trial steps

And then run the last step again for the last version

Finally, I will look at the recordings and record on the table how much time it took for each trial to fall.

STOP - have your design and procedure approved by Mrs. Edery before carrying it out.

REMEMBER - at all times, think safety first!

7. Build your parachutes.  Take photos or video and add them here.

If your plan in #5 changes, make notes.  Include measurements once you build.

        The Photos app video player is not exact enough for this so Iḿ going to take a slomo and count how many seconds it takes to reach the bottom (It only displays seconds)

        Instead of changing the area by 5 cm²

A video of me dropping the parachute 

8. Data Table:  record your observations.

        The rope size is 45 cm

        The height it was dropped at was 6ft or 183 cm

The Photos app video player is not exact enough for this so Iḿ going to take a slomo and count how many seconds it takes to reach the bottom (It only displays seconds)

9. Analyze data/Form conclusions.

Make notes here.

In general, it looks like the smaller the parachute is the faster it falls

Some more analysis and the graphs https://colab.research.google.com/drive/1zE2WqFvR8lSrVgtLwHUqg5xy1oHQPHYf?usp=sharing 

10. Conclusion paragraphs.  

Restate your hypothesis.  Use evidence to support your conclusion.  Use scientific reasoning (research about air resistance, parachutes).  Discuss how this experiment could be improved and possible sources of error.  

If the area of the parachute decreases, then the time it takes for the parachute to fall will also decrease. An experiment was conducted by dropping a parachute from six feet up and measuring the time it took for a figure to reach the ground. In the three trials of the experiment, the parachute’s area was changed by lessening the width of the parachute by 5 cm. The parachute was made using a square plastic bag with a set width. The plastic was attached to a string that was one foot long on each of its corners. The four strings were tied on to a green figure. To save time, the parachute was reused for every trial, only the bag was changed at the beginning of every trial. The width of the square plastic was decreased by 5 cm starting at 35 cm every trial. During each trial, the parachute was dropped three times and the drop was recorded in slow motion. After the drop, the amount of seconds it took for the parachute to reach the ground in slow motion was recorded. The average distribution of the data matched the hypothesis before the experiment. The average time for the first ground which had a parachute area of 1225 cm² (parachute width of 35 cm) was 8.33 slomo seconds. For reference, each slomo second is around ⅛ of an actual second, so the approximate time in seconds was 1.04 seconds. The average time for the second trial which had a parachute area of 900 cm² (width of 30 cm) was 6.67 slomo seconds (0.83 seconds). The last trial had the smallest parachute by area at 625 cm² (width of 25 cm) which had an average time of 6.33 slomo seconds (0.79 seconds). The graphs of this data show a clear grouping from smallest to highest at 6,7, and 8. The time grouping for this experiment was fairly close together with every data point remaining within 1 slomo second of its group. The graph of the average time for each parachute shows a positive correlation between the area of the parachute and the time it took for it to reach the ground. There seems to be a higher difference in time between the 1225 cm² area and the 925 cm². This may be caused by the unequal distribution of the areas of the parachutes. Although the widths increased linearly throughout the experiment, the areas increased quadratically, so the rate of change of the graph in this interval would be higher. This data is enough to give a general idea of the phenomena that is occurring, but more data should be collected to validate this hypothesis.

This experiment clearly shows an upward trend between parachute area and air time, so it supports the hypothesis. This can be explained by the four forces of flight:  lift, thrust, drag, and weight. Since the parachute is supposed to slow the figure down, drag is the most important force to slow the figure down. The interaction with the air is able to do this by applying a force to the figure in the form of air resistance. The figure is already falling due to the force of gravity so it needs an outside force to slow it down. Drag is the force in the opposite direction of motion. Since the figure is falling, the parachute is a force of drag against the motion of the figure. This can be seen with the drag equation¹ . This equation shows that area is directly proportional to drag. So by decreasing the area, the drag also decreases. The higher the drag is the slower it will fall and the lower the drag is the faster it will fall. The drag equation can be rewritten by replacing the area with w² where w is the width of the parachute. Since quadratic functions increase faster and faster towards infinity, the longer the width is the more drag it will produce. This explains why smaller width parachutes are relatively ineffective, the larger the width gets and how closely sized parachutes can be able to hold a wide range of weights. Using the drag equation, it is shown that the drag will increase with a higher parachute area, and thus the time it takes the parachute to land will decrease with more drag.

This experiment was controlled fairly well except for some problems with the setting and execution of the experiment. One problem with this experiment is the drifting involved in most of the drops. Sometimes the weight of the figure would be unevenly distributed or the parachute would have a wrinkle. Also, the parachute opened on different heights with the different parachute sizes. This may be caused by the fact that there was an air vent below where the parachute was dropped. The vent would randomly turn on and disrupt the experiment. The time was not recorded exactly after the experiment, it was limited by the time displayed in the video player. This could be solved by running the experiment in a more controlled environment and by creating a standardized way of producing the parachutes.

1.

Sources

https://www.grc.nasa.gov/www/k-12/airplane/drag1.html

https://www.grc.nasa.gov/www/k-12/airplane/drageq.html

Nasa is a really good source! (very trustworthy)