Air resistance
Weight
Prediction: I predict that during the investigation the more the weight that is loaded onto the parachute the faster it will go. I support this with my last statement up above describing the theory. The parachute will have to fall faster to compensate for the extra weight.
Fair Test: To ensure that the testing that is carried out is fair I will only change ONE variable. All the other variables that are possible to change will remain the same. I will use the same parachute throughout the whole investigation to ensure that in each different test that is made the parachute is always the same otherwise errors can occur with one parachute and not the other or on may be slightly bigger than the other giving untrue results. The following part of the investigation will explain the different variables and how they can affect the parachute and its terminal velocity.
Variables:
Mass: The more mass that is put under the parachute the faster it will fall. Weight=Mass*Gravity. This tells me that the more mass that is put on the more weight will be applied to the parachute, and thus having more weight the parachute will fall faster.
Height of deployment: The farther up the parachute is dropped from the more there is that may disturb the parachute although the ratio of the acceleration time from the parachute and the terminal velocity will be greater.
Area of the Parachute: Obviously the larger the surface is, the slower the parachute will fall, you may want to refer back to my theory to find out why.
Number of Strings: The number of strings would affect the shape of the parachute, the more the strings the more of a curve the parachute would have, making it more like a dome allowing it to trap more molecules.
Surrounding Environment: The environment is a very important part of this experiment. If the experiment took place outside the obvious concern would be the wind, the parachute would be blowing around and there may be an updraft preventing the parachute from falling down at the precise time.
Hole at the top of the parachute: Without the hole at the top of the parachute the parachute would not travel directly vertical leaving more time for it to fall in a more diagonal fashion. Although if the hole is too big air can easily escape from the top leaving the terminal velocity to increase due to the escaping air.
The only variable that I am going to change and investigate is the weight. I will keep all the others the same to allow my test to be fair and come up with accurate results to base my investigation on. Changing the weight is not a hard task, all I need to do is add a fixed mass every try. I will carry out each mass 4 times to ensure thoroughness throughout the investigation.
Surface area of parachute:50cmx50cm
Length of string:2 x60 although the string is divided into ½
Number of strings: 2 but they are joined at both ends and meet in the middle
Height dropped from:2.64m
Trial Testing
Equipment
- 1 Bin liner
- String
- Tape
- 6 2g Plastacine pieces
- Scissors
- Tape measure
- Stop watch
Method
- First I will cut out a 50x50 parachute out of a garbage bag.
- Puncture holes in each of the corners.
- Tie equal amounts of string to the parachute.
- Make sure that the parachute weights 100g.
- Choose a site to drop the parachute and measure the height of the fall.
- Using a stopwatch, calculate the time taken.
- Repeat step 3 twice.
- Repeat steps 5-7 for the masses of 200g, 300g, 400g, 500g and 600g.
- Record all results into a table and calculate the averages.
Results
Correctable Errors: By looking at the results there was no real relationship between the different weights, this may be because the initial weights were to heavy and fell to fast to time the correct times.
During the test run I realized that the parachute took time to open so perhaps when while I am holding the parachute of for deployment I should hold the parachute open to minimize the time that the parachute has with the parachute un-opened.
We took the test run inside a classroom with a controlled climate, this was very effective although there was some disturbance from the air-conditioner, when carrying out further tests the air conditioner should be switched off.
Final Method
- Review the preparations from 1-4 in the previous method before starting these next tasks.
- Raise the parachute to a fixed height of 264cm, this height is not too high nor too short for the measuring of speed. Make sure that you are holding the parachute open before dropping it. Be sure that the timer is ready. At the same time drop the parachute and start timing. Stop timing once the parachute hits the floor. Repeat this 3 times to ensure accuracy and record the results.
- After the first testing try the second one (with a different weight) eg 10 grams, 15 grams, 20 grams etc.
Results
