Wednesday, November 07, 2007
The phsyics of Skydiving
So many of you know I went skydiving some weeks ago, today I was thinking of it again and decided to crunch some numbers on the physics of skydiving. The plane has a land speed velocity of roughly 500 mph (223.5 m/s) at t=0 I fall out of the plane cruzing at 13,000 feet. After 5.7 seconds I am traveling 125 mph (55.88m/s) In those 5 seconds I have dropped 316 m and seen the plane cover a distance of just under half a mile. For the next 43.4 seconds I am weightless but experiencing a 2,000 pascal wind pushing on me. 1728 pounds of pressure are exerted over my body every inch though it doesn't seem like much is pushed with 2 ounces of thrust. In one second I will displace approximately 62 cubic meters of air.After nearly a minute of falling the 'chute opens and in a span of 3 seconds or so an additional 1,600 newtons kick you back up. In 3 seconds you decelerate from 125 miles per hour to just over 7. The decceleration is -1.78 times the acceleration due to gravity. Given that the parachuting pilot has a sadistic sense of glea, the next 10 s are spent in a madhouse stomach churning spin pulling 21,600 degrees per minute 2Pi rad/s 560 newtons a spin. Soon after your stomach returns to its initial position and the remaining 320 s are spent wondering how on Earth are you going to relieve an 890 newton harness wedgie. With 20 or so seconds left you begin to see the ground, it looks so nice and welcoming, you think to yourself that solid ground never looked quite so beautiful natural instinct kicks in your feet extend you are ready to walk home, but what you fail to realize after trying so hard to avoid that powerpole and radio antenna, is that when you set out to walk on lovely terrafied firma you will collide with her with a force of nearly 200 newtons. This hurts and is not strongly recomended. My personal suggestion is to increase your impulse time to something on the order of 5 or so seconds reducing the bone jaring impact to a mere lollup from a kitty cat on steroids. Resuming landing on the ground it then takes approximately 5.8 weeks to realize the extent of what just happened and how amaziningly cool that was!
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4 comments:
Only you. Here's a question for you though: When you leave the plane, you're still doing the roughly 500mph that the plane was doing. Do you accelerate, decelerate from there? Or is it just a change in direction?
cough...CRAZY...cough
You are doing 500mph from the plane, but only horizontally, so its very easy to end up really far from where you started--which is why the chute has controls so as to guide you back. The 500mph is slowed by the drag created by the wind, but is relatively constant through out the free fall. The major acceleration you experience is due to gravity and is directed downward. It results in a total velocity of 1312m/s e.g. roughly 515 mph along the hypoteneuse broken into 316.3 m/s down and 1274 m/s horizontally.
Science. It works, [people].
Gotta love physics!
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