Maryam AL-Naemi
10C
Mr. Hennard
Lab Report: The impact a parachutes surface area has
on its fall time.
Research Question: How does the surface area of a parachute effect the time it takes
to fall a distance of 580cm?
Hypothesis: I think that the smaller the surface are of the parachute is the less time it
would to reach the ground. Also the larger the surface area the more time it would take
to reach the ground. This is due to there being a larger air resistance meaning more air
particles collide wit the parachute. Meaning that when the surface area is smaller the
time taken for it to get to the ground is less because there are less air particles colliding
with the parachute; there will be less air resistance. ("GCSE Physics")
Background Information:
Air resistance is a force. It acts in the opposite direction to the direction you are
traveling. It is caused by molecules of air colliding with an object making it slow down or
eventually stop. It is also known as drag.("What Is Air Resistance?") The air resistance
force on an object depends on a few factors; one of which is the shape of the object.
The larger the object the more air (fluids) it needs to move out of the way meaning it has
more air resistance. Thats why race cars and jet planes are made streamlined.("Air
Resistance") Air resistance acts against gravity for an object falling down. If an object
moves left and right while falling then air resistance would be opposite, while as when it
is moving straight down gravity will pull it down and air resistance will push it up. Also
gravity is a stronger force than air resistance, that is why everything that falls eventually
hits the floor. Even when the object is at terminal velocity. ("Click Here To Play: Air
Resistance: It's All Around You!") Terminal velocity is when an object gets to a point where
it does not accelerate anymore and for a short period of time air resistance is stronger
than gravity. (Univesity today, "Air Resistance")
("9-13 Physics - Physics Workbook")
Maryam AL-Naemi
10C
Mr. Hennard
("GCSE Physics")
Apparatus:
• 4 garbage bags (100cmx100cm)
• Scissors
• Hole Puncher
• 32 pieces of 30cm string
• 4 10g Weights
• Stopwatch
• Weigh hook
• 30cm Ruler
Maryam AL-Naemi
10C
Mr. Hennard
Variables:
Type of Variable
Variable
How is it manipulated or
controlled?
Independent
Surface Area
This can be changed by
changing the size of the
parachute.
Dependent
Fall time
This is dependent on the
surface area of the
parachute.
Control
Falling distance
If this is changed then the
time would be altered for
each parachute, thus to
make it a fair lab and to
have reliable results we
need to use the same
falling distance. In order to
control this variable we
should use the same
space for each surface
area/trial.
Control
Material of parachute
The type of the material
effects the rate in which it
falls and in order to ensure
this not happening we use
the same material/brand of
garbage bags
Control
Environmental Impacts
Conditions such as wind
may impact the parachute
and the time in which it
takes to reach the ground
thus when dropping the
parachute we should use
the same place.
Maryam AL-Naemi
10C
Mr. Hennard
Method:
1. Lay out the apparatus as listed.
2. Cut the garbage bags into size 10cmx10cm. Make sure to have the garbage bag
spread out into a single sheet first.
3. Punch 8 holes into the “parachute” using the hole puncher one on each corner and
one between each corner. As such:
4. Tie strings to each one of the holes and then tie the strings together from the other
side.
5. Place 40g on the weight hook and attach it to the strings on the parachute.
6. Drop the parachute from a height of 580cm and use a stop watch to see how much
time it takes to hit the floor.
7. Repeat steps 3-6 for size 30x30, 50x50 and 70x70 to test different surface areas
and do 3 trials for each to make it a fair test.
Maryam AL-Naemi
10C
Mr. Hennard
Fair Testing
To ensure all the control
variable are controlled
well.
Keep any factors that
might impact the
parachutes fall, close the
windows and air vents.
Make sure to use the
same exact sizes for each
trial.
Data Table:
Time (in seconds)
Surface
Area(cm^2)
Trial 1
Trial 2
Trial 3
100
1.9
1
1.21
900
2.25
2.03
2.1
2500
3.53
3.75
3.54
4900
4.28
4.19
4.17
Maryam AL-Naemi
10C
Mr. Hennard
Diagram:
Graph:
Graph showing the impact of a parachutes surface area on its fall time. At surface areas
of 100cm^2, 900cm^2, 2500cm^2, 4900cm^2.
Regression Correction = 0.94
Maryam AL-Naemi
10C
Mr. Hennard
Conclusion:
In my hypothesis I stated that “I think that the smaller the surface are of the parachute is
the less time it would to reach the ground...” Looking at my results I can say with
confidence that my hypothesis was correct. The smallest surface area we used was
100cm^2 and it had the fastest time, at 1 second. The largest surface area we used was
4500cm^2 at the slowest fall time with 4.28 seconds. Both results support my
hypothesis. The graph has a positive correlation of 0.94. This means the graph is
moving along the x axis and up the y axis, meaning as x increases, so does y. So as the
surface area increases so does the fall time. The points seem to be evenly disturbed
above and below the line of best fit. This shows that there is a random error in the data,
in order to avoid this I suggest having more trials and more precise measurements (of
the time, the surface area, the strings length)
Evaluation:
!
Reliability of data:
The regression correlation of the points to the line of best fit is 0.94. In calculus anything
between 0.9-1 is considered reliable and accurate. Also when looking at the graph you
can the points are more or less all close to the line of best fit making it reliable. I
conclude by saying the data was reliable
!
Reliability of method:
A stopwatch was used to measure the fall time of the parachute, a few mistakes might
have happened here. The person with the stopwatch might have been a second late or
a second fast. Effecting the reliability of the method, but since in this case all three trial
for each surface area were fairly close these errors are very unlikely.
Another thing that might tamper with the reliability of the method is how well we
controlled the variables. Factors like wind and other environmental factors might effect
the fall time, since we did the lab and all the trial in a short time span all of these factors
didn’t change. They were the same for all trials and surface areas. We did 3 trials and
we had someone different do it each time so that if there was a random error it might be
taken out of the equation. Overall the method was reliable.
!
!
Validity:
Air resistance is one a huge factor of this lab, in the process of doing and making this
lab a few measuring instruments weren’t used correctly. For one, when punching holes
into the parachutes, the holes might very in size. If thats the case then more air
molecules will be let in tampering with the data. Also when cutting the garbage bags, the
sizes where measured using a 30cm ruler meaning the ruler will have to be reused for
sizes like 70cmx70cm or 50cmx50cm. The likely hood of the areas being wrong by 1 or
2 cm is very likely, a 1meter ruler would have given us more valid data. The control
variables were controlled well and measured well using the appropriate instruments.
The method gave us valid data.
Maryam AL-Naemi
10C
Mr. Hennard
Weakness or Problem with method
Suggested improvements
It didn't mention how big the holes for the Use more detailed references to the
string had to be or how thick the string
apparatus
was.
It didn’t explain the type of knot use for
the ropes
If a loose knot was made it would make
the parachute snap, mentioning or
explaining how to tie the knot would help
avoid this.
It didn’t say that you should record your
findings
To mention to recording findings,
preferably in a well labeled table.