Skydiving!!

By Molly McKone and Sarah Crist
Question: What physics are involved in skydiving?


Answer: What goes up must come down. There are two initial forces acting on you when you jump out of the plane: the Earth's gravity pulling you straight down, and friction with the air. While you are falling and going through the air some other forces are free-fall and terminal velocity.


Skydibing Animation
Skydibing Animation

-Gravity: When you jump out of the plane, all objects are all pulled by gravity in the same exact way, making air resistance and surface area the forces that make things fall slower. This is why a skydiver uses the all important parachute. Newton said that the gravity that makes all objects that go up come down on Earth and the gravity that keeps the planets together is the same. Gravity is what pulls a skydiver to Earth. When the skydiver begins to fall gravity pulls acts upon them, pulling them all the way to Earth and accelerating at an even velocity. The skydiver falls at the speed of 9.8 m/s/s. Gravity acts on the skydivers mass creating a force which pulls the jumper closer to Earth, and causes them to accelerate. The equation for this is: weight= mass of the skydiver times gravity.

external image SunsetTandem.jpg

-Air Resistance: As a skydiver is falling through the air the gravity is pulling them down and at the same time air resistance is opposing gravity. Air resistance is the air molecules falling into a falling object creating drag and friction. The amount of air resistance created depends mostly on surface area and the speed of the falling object. The air resistance creates friction between the skydiver and the air. This slows the speed of the skydiver falling down. Air resistance slows the falling process down making it easier to land. In order to increase air resistance a large parachute is used to increase surface area and increase air resistance.



-As an object falls in air:



  • its speed increases.



  • the air resistance force on it increases.



  • the net force on it decreases.



  • its acceleration decreases.



until it reaches terminal velocity, where the net force on it and its acceleration are zero.



-Gravity and Air Resistance eventually equal each other and acceleration stops. To slow down the upward force needs to be greater than the downward force. When you open a parachute the air resistance becomes greater than gravity. The forces aren't equal any more so the skydivers speed slow downs. The air resistance becomes equal with gravity because the speed is slower. The constant speed is much slower. Falling to the ground is much easier slower than when you first jump out of the plane. When the skydiver hits the ground there is a strong force from the Earth.

Physics of Skydiving animation:
http://www.waowen.screaming.net/revision/force&motion/skydiver.htm


Summary:

Bibliography:

-http://www.physlink.com/education/askexperts/ae536.cfm

-http://www.physicsclassroom.com/mmedia/newtlaws/sd.cfm

-http://hypertextbook.com/facts/JianHuang.shtml

-http://thephysicsofskydiving.homestead.com/index~ns4.html-

-http://www.skydive-dc.com/SunsetTandem.jpg -http://www.lancs.ac.uk/ug/shrine/

-http://www.waowen.screaming.net/revision/force&motion/skydiver.htm