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YEAR 8 MYP SCIENCE
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YEAR 8 MYP SCIENCE
Parachute Investigation
Research Question:
How does varying the mass of sand in a bag ([weight]e.g.10g,20g,30g,40g,50g )which is attached to a parachute
with canopy area of 10000cm2 and a string length of 10cm attached to the 4 corners of the canopy which has a hole
in the center(to maintain a straight course) and in total weighs 7.9g without the sand, affect the time the parachute
takes to drop from the fourth floor to the LG floor, outside the science room which is measured by a stopwatch?
This test will only work if the:canopy size,length of string, wind speed and direction,height of drop,
climate( temperature and air pressure), release point, location of central hole are the same and there are no
unwanted punctures in the canopy. This is being studied because it can help solve dilemmas like the one at
Queenstown Skydiving Center where a 160 kg man broke his leg because he fell too fast, this is due to an
unconfirmed reason. One of the probability is that the canopy was too small and that there wasn't enough air
resistance to slow him down. Does increasing the mass of a weight connected to the parachute effect the time it
takes to land.
Hypothesis:
The higher the mass of a weight that is attached to the parachute with 10cm of string attached to the 4 corners of
the canopy with an area of 10000cm2 and a hole in the center(to maintain a straight course)and weighs 7.9g
without the sand, and is dropped from the fourth floor to the LG floor, the shorter the time(measured by a
stopwatch) it would take to land in the LG floor.
This is because when released each weight will initially cause the whole parachute to accelerate and as it gains
speed it encounters an escalating amount of air resistance. The parachute will persist to gain speed(unbalanced
forces) in the air until the air resistance is large enough to balance the force of gravity. At this point the parachute
stops accelerating, this is the terminal velocity. It will continue falling at a persistent speed until touching the
ground.Hence weights with a larger mass experience a greater force of gravity. They will have to accelerate for
longer time before there is sufficient air resistance to balance the force of gravity to reach the terminal
velocity.They will have a higher gravitational force acting on them but will have the same amount of air resistance
compared to a parachute with a lower mass. Hence it accelerates for a longer period of time before reaching a
terminal velocity as a result increasing its net speed of travel.
The fact that a higher mass will fall faster than a lower mass is shown in the formula (Gravity*Mass(KG)= Force
In Newtons) because the force in newtons for a parachute that weighs 17.9g will have a gravitational force of
0.175599 Newtons(9.81m/s*0.0179kg) exerted on it but a parachute that weighs 27.9g will have a gravitational
force of 0.273699 Newtons (9.81m/s*0.0279kg) exerted on it. This clearly shows that heavier objects will have
more gravitational force exerted on it compared to a lighter object. In conclusion the heavier weights will fall
faster than the lighter weights because they take longer to reach a terminal velocity due to a larger force of gravity
acting on them.
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Variables:
Independent Variable
Mass of the parachute
YEAR 8 MYP SCIENCE
The independent variable will be changed by the mass of the sand bag in
intervals of 10g,20g,30g,40g,50g. This will be measured on a scale and to
increase the mass of sand put more sand in the bag.
Dependent Variable
Measure the time the parachute takes to drop 5 stories using a stopwatch.
Time the parachute takes to To increase the reliability of the time of the drop use two stop watches
drop 5 floors
and find the mean time of both.
Controlled Variables
Canopy Size
Keep the canopy size the same (10,000cm2) by using the same
parachute which would be measured to the exact millimeter to make
sure an exact fair test.
Length of String
Keep the length of string the same (10 cm) by using the same string
which would be measured to the exact millimeter to make sure an exact
fair test.
Wind speed and direction
Keep the wind speed and direction(no wind interference) the same by
dropping a test parachute to see if it blows of cores if it doesn't then
drop the real experiment parachute this is to make sure an exact fair
test.
Height of drop
Keep the height of drop the same by dropping the parachute from the
fourth floor every time this is to make sure an exact fair test.
Climate( temperature and
air pressure)
Keep the climate( temperature and air pressure) the same by dropping
the parachutes on the same day (usually the air pressure and
temperature stay close to the same trough out the day) this is to make
sure an exact fair test.
Release point
Keep the release point the same by marking the spot on the parachute
where to drop it from this is to make sure an exact fair test.
Location of central hole
Keep the location of central hole the same by using the same parachute
which would be measured to the exact millimeter to find the absolute
center for the whole this will make sure an exact fair test.
Unwanted punctures in the
canopy.
Keep out the unwanted punctures in the canopy by inspecting the
canopy for holes after each drop, if there are any seal them up with
scotch tape. This will insure a fair test.
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YEAR 8 MYP SCIENCE
Materials:
Sand(150grams[10g, 20g, 30g, 40g, 50g])
meter ruler X 1
Scissors X 1
Stopwatch X 2
Weighing Scale X 1
String (40 cm[4pcs of 10cm each])
Measuring Spoon X 1
Grocery Plastic Bags X 1 roll (1m2 area minimum)
Zip Lock Bag X 5
Compas X 1
Marker X 1
Tape X 1 roll
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YEAR 8 MYP SCIENCE
I.
Measure the canopy area (length* width) of the parachute, by measuring out a 1m*1m square of the grocery
plastic bag using a meter ruler and double check the dimensions.
II. Find the exact center of the canopy and draw a 0.5 mm circle around it.
III. Carefully cut out a hole in the center following the line that was just drawn
IV. Mark a dot on all the four corners
V. With the tip of the scissors poke a small hole on each of the corners for the string to go through
VI. Cut out 4pcs of 10cms string, measure it using the ruler and cut it with the scissors
VII.Thread the string through the hole and tie a knot to secure
VIII. Label each of the zip lock bags with each of the different masses of sand going in to them (e.g.10g, 20g,30g,
40g,50g)
IX. Weigh out the sand using the spoon, to the exact milligram and pour it into it’s respective zip lock bag
X. Using the tape stick all the 4 strings (10cms each) to the sand bag that needs to be used for that respective drop
in the experiment
XI. Double check for any holes in the parachute other than the one in the center
XII.If any unwanted holes are found seal them up with scotch tape
XIII. When ready drop the parachute from the fourth floor and make sure there are a minimum of two people on the
land site to record the time the parachute takes to drop from the fourth floor to the LG floor
XIV.Record the time (seconds) the parachute takes to fall using two stopwatches(make sure to round to two
decimal places)
XV.Important Point to Note: Keep all the controlled variables controlled .
XVI.find the average of the two times
XVII.record the average time on the table of results in the correct cell
XVIII. If all repeats(3 for each mass) of that change of the independent variable is completed then remove the tape
from the zip lock bag, if not then ignore this step.
XIX. Repeat steps from 9 through to 16 for all the repeats(3) of each change of the independent variable(5
changes)
XX.In the table add one column for the average time of all repeats of the same drop and fill in the column
XXI.Make an appropriate graph of the averages column which should include a trend line
XXII.X axis = mass of sand
Y axis= average time taken to fall for each mass
Safety Precautions:
This experiment is one without any major safety risks but since it involves dropping things from a
height it is important to be informed about the very few safety risks that come with this
experiment. Since this experiment involves dropping parachutes with sand bags which is detach
from the parachute could injure anyone if it falls on them, that is why it is highly important to
check that the connection between the string and the sand bag is strong and that no one is near the
landing site other than the timers. One more safety risk is that when filling up the sand bag one has
to do it extremely slowly or else the sand might fly into someone’s eye.
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YEAR 8 MYP SCIENCE
Results:
Sample Calculation for Average:
(31.18+37.00+35.83)/3 = 34.67
Mass of sand
bag in Grams
Time taken to
reach the LG
Floor from the
4th floor. R1
(in seconds)
Time taken to
reach the LG
Floor from the
4th floor. R2
(in seconds)
Time taken to
reach the LG
Floor from the
4th floor. R3
(in seconds)
Average Time
taken to reach
the LG Floor
from the 4th
floor. (in
seconds)
10.00
31.18
37.00
35.83
34.67
20.00
30.18
32.37
30.04
30.86
30.00
23.63
20.56
26.12
23.43
40.00
21.38
23.49
22.24
22.37
50.00
15.58
19.86
17.09
17.51
Graph:
Time Taken To Fall From The 4th Floor To The LG Floor In
Seconds
How does varying the mass of sand in a bag ([weight]e.g.10g,20g,30g,40g,50g )which is
attached to a parachute with canopy area of 10000cm2 and a string length of 10cm attached to
the 4 corners of the canopy which has a hole in the center(to maintain a straight course), affect
the time the parachute takes to drop from the fourth floor to the LG floor, outside the science
room which is measured by a stopwatch?
Mass of sand in a bag(grams) that is attached to a parachute which weighs 7.9g.
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Conclusion & Evaluation:
YEAR 8 MYP SCIENCE
The Final results were what I expected and supports my hypothesis that a larger mass of sand attached to
a canopy will fall faster than a smaller mass this is because larger masses for the weight cause the
parachute to accelerate for a longer period of time and reach its terminal velocity(even balance between
the gravitational force and the air resistance) later than a parachute with a lower mass. This is due to the
fact that the gravitational force on earth causes all object to free fall at a rate of 9.81m/s and to calculate
the gravitational force exerted the parachute use the formula Force in Newtons = Gravitational
Acceleration * Mass in Kg, this is the gravitational force exerted on the parachute throughout the drop.
But the air resistance varies throughout the drop but is equal to the gravitational force once the parachute
reaches its terminal velocity. This is not always the case, if this test was to happen on earth but an area
with no air(a vacuum) then there would be no air resistance hence all objects no matter the mass will fall
at the same speed (the gravitational acceleration). This is shown in the SUVAT equation, S=UT+1/2AT2 ,
when this equation is worked out then the time any object would take to fall five stories is revealed,
which would be 1.75 seconds.T
The result of the experiment proves that my hypothesis is correct, that the mass of the weight attached to
the parachute affects the speed at which it falls and also the falling time. The weights with a higher mass
experiences a greater force of gravity which in turn takes less time to fall, this is shown in the graph’s
solid downward trend line where the x axis represents the mass of the sand and the y axis represents the
time it takes to fall. The average time the parachute takes to fall with a sand weight of 10g is 34.67
seconds but the average time the parachute takes to fall with a sand weight of 50g is 17.51 seconds.
This test was unreliable because there was not enough of a difference between each of the intervals of the
independent variable hence I could not find the max speed that a parachute with a canopy area of 1m2 and
the expected gentle downward curving slope. Next time I should have a greater range of the independent
variable. Plus the results were not reliable because the parachute swayed and spun in mid air which in
turn increase the time it takes to fall.
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YEAR 8 MYP SCIENCE
The strengths of my method are: easy to follow, materials are easily available, economical materials and
there is no major safety risk. Plus its an appropriate method in order to understand the gravitational force
and the air resistance acting on the parachute.
Problem
Suggested solution
Sudden wind gusts came in while the parachute
was in mid flight and many times blew it off
course, hence we could not use that data.
This problem can be solved by doing this
experiment in an indoor area where there will be
no sudden gusts of wind and the weather is
controlled. This will allow fair testing to be done
because the parachute wont fly any where
unexpectedly.
Many times while the parachute was in mid air
some unwanted punctures form due to the plastic
not being able to withstand that kind of stress.
This problem can be solved by using a stronger
material for the parachute canopy because a
stronger material can handle more stress than a
simple grocery plastic bag hence it will not form
unwanted holes.
Occasionally the parachute was released from a
different point which then affected the parachute
because it doesn't open up the same way if
released from a different point. This caused the
parachute to fold in an inconsistent way,which
varied the air resistance on the parachute.
This problem can be resolved by spraying the
inside of the parachute with nonstick coating to
reduce the friction between the plastic canopy
which will reduce the chances of the canopy
folding. This will insure a fair test.
The parachute was dropped on different days and
there was a temperature difference of 5oc which
on the hotter day caused to parachute canopy to
expand and on the cooler day it contracted.
This problem can be solved by doing this
experiment in an indoor area where the weather is
controlled. This will allow fair testing to be done
because the parachute canopy wont expand or
contract unexpectedly.
When unwanted holes form on the canopy they
were sealed by scotch tape which increased the
weight of the parachute canopy.
This problem can be solved by sealing the holes
using an electric sealer which wont increase the
weight or the canopy size of the canopy.
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YEAR 8 MYP SCIENCE
An extension to this experiment could be:
1. To vary different controlled variables in order to find the reason the parachute spins in mid air and
why the strings get tangled up.
2. To do this in an indoor vacuum tunnel to find the exact time the parachute will take to drop from a
14m height with no air resistance. How much does the results differ from the results recorded in this
experiment ?
3. To do this experiment with a much wider range of masses as the weights. Does this affect the trend
line space of the graph? Can the max terminal velocity be determined by changing the independent
variable in variations of 10g, 30g, 50g, 70g, 90g ?
This experiment does prove that heavier the mass of the weight connected to the parachute the faster it
will drop. Hence it stated that to stop accidents like the one in Queenstown Skydiving Center the world
needs to have a standard tested size of parachute canopy for each weight category for 30kg-150kg.
Theoretically the heavier one is the larger parachute canopy one will need.
References
Agarwal, N. (2014, December 11). Homework Time. Speech presented at Science Class in Hong Kong, Tung Chung.
Equations of motion. (2014, November 12). Retrieved December 11, 2014, from http://en.wikipedia.org/wiki/
Equations_of_motion
Forster, A. (2014, December 09). SUVAT EQUATIONS. Speech presented at Science Class in Hong Kong, Discovery Bay.
How to Calculate the Force of Gravity on the Earth’s Surface. (n.d.). Retrieved December 11, 2014, from http://
www.dummies.com/how-to/content/how-to-calculate-the-force-of-gravity-on-the-earth.html
PHYSICS - equations list. (n.d.). Retrieved December 11, 2014, from https://sentynel.com/media/old/equations.html