Chuck (mass = 70 kg) and Dan (mass = 80 kg) are working as window washers at Walter
Library. Chuck gets the bright idea of tying each of them to either end of a rope and hanging
it over a pulley to wash the windows. Chuck stands on the flat roof while Dan hangs from
the other end of the rope, ten meters off the ground. (See illustration below.) However,
it begins to rain, reducing the frictional force between Chuck’s shoes and the roof, and he
If the value of the coefficient of kinetic friction between Chuck’s shoes and the wet roof
μk = 0.25, (a) what is the acceleration of Chuck and Dan?
(b) What is the tension in the rope while they are accelerating?
(c) With what speed does Dan land on the ground below?
Neglect the mass of the rope and the pulley.