posted by Talia on .
A 170 pound man has to slide down a rope that can only support 150 pounds. How long will it take him to reach the ground 35 feet below if he keeps the rope from breaking?
To barely avoid breaking the rope, he needs to apply a force of 150 lb to the rope. There will be a net 20 lb downward force on him and he will accelerate downward at a rate
a = Fnet/m = 20/(170/g)= 0.1176 g
= 3.79 ft/s^2
The time to slide L = 35 ft down the rope will be
t = sqrt(2L/a)= 4.3 seconds