Two window washers, Bob and Joe, are on a 3.00 m long, 310 N scaffold supported by two cables attached to its ends. Bob weighs 890 N and stands 1.00 m from the left end, as shown in the figure below. Two meters from the left end is the 500 N washing equipment. Joe is 0.500 m from the right end and weighs 990 N. Given that the scaffold is in rotational and translational equilibrium, what are the forces on each cable?Left cable?____kNRight cable?____kN
Both support 1/2 the scaffold weight, = 155N. Bob's weight spread ratio is 3:1, so divide his 890 by 4. That puts 222.5N. on the right cable, and 667.5N. on the left. Joe's weight spread is (2.5/0.5) = 5:1, so divide his weight by 6. That puts 165N. on the left cable, and 825N. on the right. The washing gear weight ratio is 2:1, so divide its weight by 3. that puts 166.67N. on the left cable, and 333.33N. on the right. Total left cable force = (155 + 667.5 + 165 + 166.67) = 1154.17N. Total right cable force = (155 + 222.5 + 825 + 333.33) = 1535.83N.
