An 8.0 m long uniform ladder of mass 20 kg is placed against a smooth (frictionless)…
PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
An 8.0 m long uniform ladder of mass 20 kg is placed against a smooth (frictionless) vertical wall. The bottom of the ladder rests on level ground that has a coefficient of static friction μs with the ladder. The ladder makes an angle of 60° with the ground. A firefighter of mass 70 kg climbs the ladder.
Assume the ladder remains in a single vertical plane and the firefighter’s weight acts at the point he occupies along the ladder’s length.
(a) When the firefighter is halfway up the ladder, determine the minimum coefficient of static friction μs,min required between the ladder and the ground to keep the ladder from slipping.
(b) If μs=0.45, calculate the maximum distance the firefighter can climb along the ladder (measured from the bottom) before the ladder begins to slip.
(c) Describe how the required coefficient of static friction would change if the angle the ladder makes with the ground were decreased, and support your explanation with physical reasoning.