thanks again corey. i did mean 77mph and not meters per hour. i think the formulas you are talking about are on the site that yasmeen linked. (go to home, then topic index, then force, then 'force of a bat on a baseball' and scroll down)
oh yeah, you won't have to worry about the chalk either, dude is not in to that kind of thing. he may leave some fecal stains on the rock, but no chalk.
Falling down
-
Horatio Felacio
- Posts: 3338
- Joined: Tue Sep 24, 2002 7:26 pm
If your rope stretches 10%, take 1/10th of the length that is out, and since you know the velocity, use Legion's equation above to solve for the deceleration. Then use F=ma (how much does dude weigh?) to solve for force on the anchors. We're assuming constant decel and neglecting the spring constant for the rope, but this simplifies the math and gets you in the ball park.
BTW, a 400 ft. fall should be no problem as far as the rope is concerned. Remember that guy that was trying to score a 1000' ft. jump? I can't remember his name, but he died from a different law of physics when he set up his ropes the last time he jumped. (Oh, yeah, Dan Osman)
BTW, a 400 ft. fall should be no problem as far as the rope is concerned. Remember that guy that was trying to score a 1000' ft. jump? I can't remember his name, but he died from a different law of physics when he set up his ropes the last time he jumped. (Oh, yeah, Dan Osman)
I assumed zero loss during the fall. The man and the rope must absorb nearly 120,000 Joules of energy developed from the fall. I don't like the Petzl site's incorporation of friction during the fall, because, with no obstructions the rope would do nothing but rest on the bolt/biner and fall with, not slow down, Dude. Figuring 64m of rope to stretch over (belayer about 4m below bolt) and 7% elongation, the guy and rope will have about 14 feet (4.2m) of negative acceleration to reach 0 velocity. By my calculations (again, assuming correct formula), that's 17g's...-169.55 m/s^2 (that value was higher when I ignore air friction as used 109 mph, not 85). Bottom line, I guess, don't climb 60 meters above your closest protection.
"I never saw a wild thing sorry for itself. A small bird will drop frozen dead from a bough without ever having felt sorry for itself."
D. H. Lawrence
D. H. Lawrence
So, what's the final terminal velocity (taking into account air resistance, friction, etc.) and what is the impact force?
I feel alot worse for the belayer than Dude, I am reminded of the story of Hidetaka Suzuki who was belaying Dan Osman when Dan had cut some of the wires on his stoppers and webbing to take a long whipper while his pieces failed. This fall was shown on one of the Masters of Stone videos, I don't rememeber which one though. Apparently Hidetaka got pulled up from his belay ledge and into a roof above, he had lots of injuries while Dan was none the worse for the wear.
I feel alot worse for the belayer than Dude, I am reminded of the story of Hidetaka Suzuki who was belaying Dan Osman when Dan had cut some of the wires on his stoppers and webbing to take a long whipper while his pieces failed. This fall was shown on one of the Masters of Stone videos, I don't rememeber which one though. Apparently Hidetaka got pulled up from his belay ledge and into a roof above, he had lots of injuries while Dan was none the worse for the wear.
"But what is happiness except the simple harmony between a man and the life he leads?" – Lord Byron
