A tower crane ( Figure 1 ) must always be carefully balanced so that there is no

Question

A tower crane (Figure 1) 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 am = 3100-kg air-conditioning unit. The crane's dimensions are shown in (Figure 2) . The crane's counterweight has a mass of M = 9400kg . Ignore the mass of the beam.

Part A

Where must the crane's counterweight be placed when the load is lifted from the ground? (The counterweight is usually moved automatically via sensors and motors to precisely compensate for the load.)

Express your answer to two significant figures and include the appropriate units.

Part B

Determine the maximum load that can be lifted with this counterweight when it is placed at its full extent.

Express your answer to two significant figures and include the appropriate units.

Explanation / Answer

balance torque on any point on the vertical pillar,

m*7.7=M*x

3100*7.7=9400*x

x=2.54m

for maximum m,we can place M at extreme position

9400*3.4=m*7.7

maximum m=4150 kg

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