Chapter 12, Problem 4P

(I) A tower crane (Fig. 12–48a) must always be carefully balanced so that there is no net torque tending to tip it. A particular crane at a building site is about to lift a 2800-kg air-conditioning unit. The crane’s dimensions are shown in Fig. 12–48b. (a) Where must the crane’s 9500-kg counterweight be placed when the load is lifted from the ground? (Note that the counter-weight is usually moved automatically via sensors and motors to precisely compensate for the load.) (b) Determine the maximum load that can be lifted with this counterweight when it is placed at its full extent. Ignore the mass of the beam.