# Homework Help: Rock climber elastic rope problem

1. Sep 30, 2008

### hewhoeatspie

SOLVED

1. The problem statement, all variables and given/known data
Two rock climbers, Bill and Karen, use safety ropes of similar length. Karen's rope is more elastic, called a dynamic rope by climbers. Bill has a static rope, not recommended for safety purposes in pro climbing. Karn falls freely about 2.0m and then the rope stops her over a distance of 1.0m. (a) Estimate, assuming that the force is constant, how large a force she will feel from the rope. (Express the result in multiples of her weight.) (b) In a similar fall, Bill's rope stretches by 30cm only. How many times his weight will the his weight will the rope pull on him? Which climber is more likely to be hurt?

2. Relevant equations
(Not entirely sure)
d=g(0.5)t^2
a=v/t

3. The attempt at a solution
d=g(0.5)t^2
1.0=9.8(0.5)t^2 = t=0.45
(I used a simulation to get that something that falls for 2m will be falling at a velocity of 6.2 m/s....I'm not the best at physics.)
v=6.2m/s
a=(-6.2m/s)/0.45 = a=-13m/s^2
F=Frope-Fg
ma=Frope-Fg
Frope=ma-Fg
Frope=m(-13m/s^2)-Fg
???

That that's where I got stumped. I'm sorry if I didn't provide enough information, or if it was jumbled, I'm new here.

I haven't even tried the second half.....

EDIT: Nevermind, I got some help and solved it.

Last edited: Sep 30, 2008