# Calculate moments and forces using 3 conditions of Equilibrium

1. Oct 25, 2011

### Mattmiles

1. The problem statement, all variables and given/known data

A firefighter needs to rescue a person from a blazing mansion. His ladder is 12 m long and because of the design of the house he cannot place it closer than 6 m from the wall. But this is not high enough to reach the window where the victim of this fire is waiting to be rescued. So, he climbs to the top of the ladder and throws a (fireproof) rope into the window. He ties the end of the rope to the top of the ladder and our victim ties her off end to something convenient inside the room. The firefighter (which includes his equipment, breathing apparatus etc.) has a mass of 192 kg, the victim a mass of 48 kg and the ladder also has a mass of 48 kg. The limiting coefficient of friction at both ends of the ladder is μ = 0.51.

Calculate the minimum strength of the rope.

2. Relevant equations

Equilibrium = Ʃhorizontal = ƩVerticval=ƩMoments

3. The attempt at a solution

I have no idea where to begin or even how to attempt this question. If anyone could help I would be very appreciative?