posted by Sarah .
A construction worker attempts to lift a uniform beam off the floor and raise it to a vertical position. The beam is 2.77 m long and weighs 472 N. At a certain instant the worker holds the beam momentarily at rest with one end a distance d = 1.44 m above the floor, as shown in Fig. 12-75, by exerting a force on the beam. (a) What is the magnitude of ? (b) What is the magnitude of the (net) force of the floor on the beam? (c) What is the minimum value the coefficient of static friction between beam and floor can have in order for the beam not to slip at this instant?