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?

1 answer

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