(a) Show that the beam of Problem 8.41 cannot be moved if the top surface of the dolly is slightly lower than the platform.

(b) Show that the beam can be moved if two 175-lb workers stand on the beam at B and determine how far to the left the beam can be moved.

PROBLEM 8.41

A 10-ft beam, weighing 1200 lb, is to be moved to the left onto the platform. A horizontal force P is applied to the dolly, which is mounted on frictionless wheels. The coefficients of friction between all surfaces are μs = 0.30 and μk = 0.25, and initially x = 2 ft. Knowing that the top surface of the dolly is slightly higher than the platform, determine the force P required to start moving the beam.

10 ft 2 ft