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# Parachute Project

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by

## Chloe Shawah

on 25 February 2013

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#### Transcript of Parachute Project

Parachute Project! by Chloe Shawah and Alia Aguilar Scientific Question... Which material of parachute will decrease the speed of a falling object the most? Independent Variable... Material Dependent Variable... Average Speed... Meters/Second Control Group... No Parachute Controlled Variables... Drop Height
Mass and Size of Object Dropped
Size of Parachute
Length, Material, and Number of Strings Hypothesis... If parachutes are made out of different materials, then the parachute made out of plastic will have the lowest average speed when dropped. Hypothesis Explanation... We think the plastic bag will decrease the speed of the falling object the most. We read that Nylon and polyester are or were used in parachutes, but also that the materials used should be waterproof, light, and flexible. The plastic bag seems to fit more of those criteria than any of the other materials. Also, parachutes work by increasing the surface area of the object to increase its air resistance so it balances out with gravity at a lower speed and stops the acceleration. This is, put simply, lowering its terminal velocity. According to Newton’s First Law of Motion, the object that is falling will not slow down by itself, unless an unbalanced force acts upon it. The normal force of a person standing on land is removed and the person will not stop naturally until that force is returned once again on land. The parachute increases air resistance and the friction it causes, therefore unbalancing the forces and slowing the object and lowering its average speed. Procedure for Making Parachutes Procedure for Conducting Experiment Cut a circular canopy with a diameter of 24cm
from a plastic bag Cut a circular vent with a diameter of 2cm in the
center of the canopy Cut 6 slits at equal intervals around the edges of
the canopy Cut six 12cm strings and tie one through each of
the slits Repeat steps 1-5 with Nylon and Polyester Tape the parachute strings to the Lego man Measure and mark a 3 meter dropping
point Drop the Lego man from your dropping
point Record how long it took the Lego man to
reach the floor Repeat steps 2 & 3 for 4 more trials Repeat steps 2-4 for the Plastic, Nylon,
and Polyester parachutes. Find the average speed for each parachute No parachute had the
highest speed, showing
that the parachute did
have an effect. Plastic has the lowest speed,
which means it was the most
effective parachute. The plastic parachute is a circular parachute and has a
diameter of 24 cm, one circular vent with a diameter of
2cm in the middle, and six 12cm strings. The canopy was made
from a plastic Big Y shopping bag and the strings were made
from craft cord. Air resistance will push up on the parachute
and air will be forced through the vent or up the sides creating a drag as gravity pulls it down. Skin friction will further slow the parachute when air rushing along the canopy and strings creates additional friction. This parachute is not porous because the
plastic is airtight and will trap the air instead of
slowing it. The nylon parachute is a circular parachute and has a
diameter of 24cm, one circular vent with a diameter of
2 cm in the middle, and six 12cm strings. The canopy was made from a nylon slip and the strings were made from craft cord. Air resistance will push up on the parachute and air will be forced through the vent or up the sides creating a drag as gravity pulls
it down. Skin friction will further slow the parachute when air rushing along the canopy and strings creates additional friction.
The nylon is porous so air will slow down when it passes
through it and slow down the parachute even more. The polyester parachute is a circular parachute and has a diameter of 24cm, one circular vent with a diameter of 2cm in
the middle, and six 12cm strings. The canopy was made from a 100 percent polyester bandana and the strings were made from craft cord. Air resistance will push up on the parachute and air will be forced through the vent or up the sides creating a drag as gravity pulls it down. Skin friction will further slow the parachute when air rushing along the canopy and strings creates additional friction.
The polyester is porous so air will slow down when it passes
through it and slow the parachute even more. Plastic Parachute Nylon Parachute Polyester Parachute Side View of Parachute Layout of Parachute Fabric Close-ups of Fabrics Plastic Nylon Polyester These were not the exact fabrics we used to make our parachutes, but were of the same material and will still give you a good idea of the consistency of the fabrics. Summary of Results By conducting this experiment, we found that the plastic bag was the most effective material for slowing the parachute down. The plastic was about .5 meters per second slower than Nylon and Polyester, at 1.44 m/s and was slower that our control group (no parachute) by 4.5 meters per second. This shows that our hypothesis was accepted, and that the parachutes were the variable slowing the fall. Nylon and Polyester were both very close, with Nylon .3 m/s slower than Polyester at 2.03 m/s. We observed that plastic parachute often spiraled as it fell, which made it take a longer time to hit the ground, which might have been one reason for its effectiveness. We also observed when observing the materials that the molecules in the plastic were compact and close together, much more so than the Polyester, and slightly more than the Nylon, which proves that the material you make a parachute out of should be very airtight and compact. Diagram of Forces Air resistance is the air's mass pushing up against the parachute and will slow it down. Air resistance is also sometimes called drag. When you increase air resistance, you will balance out with gravity faster, and lower your terminal velocity. Gravity is the Earth pulling objects down and would pull both the parachute and the man down at an acceleration of 9.8 m/s squared in a vacuum, but not with air resistance and other variables acting on the parachute. Real Life Situation We now recommend that when parachutes are made, they use airtight, waterproof, and very light materials. Our results showed us that plastic, the material with all of these qualities was the most effective in slowing the parachutes down and allowed for the most air resistance to take place and further decelerate the descent. Therefore, when someone has jumped out of an airplane whether for recreation or to help someone, the parachutes should be made out of plastic or a thin, light piece of rubber which possesses the same qualities. We also however, observed that when the parachute makes gentle loping turns as it falls, the descent takes longer and is traveled at a lower speed. We think it would be beneficial to research this theory and design a parachute that would allow the turns because if they are kept controlled, they could make it safer for the jumpers. 0 m 20 m 15 m 10 m 5 m 6.99 m 6.09 m 4.32 m 18.15 m No Parachute Plastic Nylon Polyester After 3 seconds the parachutes will be … Diagram of Parachute Falls Pictures of Our Experiment Motion of the Parachute When the Lego is dropped, there is no normal force to hold it up and the Lego and parachute begin to fall as gravity pulls it down. This Lego would stay in motion and accelerate, and according to Newton’s law of inertia, an unbalanced force is needed to change the rapid acceleration, which is the parachute. The air around it pushing up creates air resistance on the increased surface area of the parachute, and slows its acceleration, and lowers it terminal velocity, which is when the air resistance balances out with gravity and the object can accelerate no further. Also, when the air is forced to rush up through the vent or around the sides, the friction increases and the air resistance as well. The Changes' Effects We changed the material of the parachute, which meant that for every one we used, we slightly changed mass, strength, and the way the air will flow. We chose nylon and polyester because they were both relatively strong, although kind of heavy, and are often used to make parachutes. We chose plastic because it is very, very light, and no air will get through it. Based on our results that the plastic was most effective, we can conclude that a light, airtight material would be ideal. Newton's First Law Newton's Second Law Newton's Third Law The falling Lego man demonstrates the law of inertia because it says that an object in motion tends to stay in motion, and an object at rest tends to stay at rest unless acted upon by an unbalanced force. We had to overcome the inertia of the Lego and get it to slow its fall (motion) by creating an unbalanced force (the parachute) to slow it down and lower its terminal velocity. The way we chose our materials was an example of Newton’s second law of motion, which says that force x mass = acceleration. In order to make sure that the acceleration of the parachute was the lowest we could make it, we realized that we couldn’t change the force of the drop, just the mass of the parachute to make it the most effective. This meant that we had to choose the lightest materials possible, which led us to plastic, and also the strongest, which led to polyester and nylon. Also, the result that the lightest material had the longest descent time proves that the lower the mass, the lower the acceleration. The way the air pushed up on the falling parachute was an example of Newton’s 3rd Law of Motion, which is that every action has an equal and opposite reaction. The parachute falling and pushing on the air was the action, and the reaction was the air pushing back on the parachute (air resistance or drag), and was the only reason that any of our parachutes were effective.
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