A cable weighing 0.6 pounds per foot is attached to a small 70-pound robot, and then the robot is lowered into a 50-foot deep well to retrieve a 7 pound wrench. The robot gets out of the well (carrying the wrench) by climbing up the cable with one end of the cable still attached to the robot. How much work does the robot do in climbing to the top of the well?

4600 ft.Ibs

Explanation:

Work done by the robot in climbing to the top of the well = work done in carrying the cable and itself + work done in carrying about average half the mass of the cable attached to the robot

Now work done = Force × distance = (( 70 +7 ) × 50 ft) + (( 0.6 × 50 ft) × 25 ) = 3850 + 750 = 4600 ft.Ibs

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