The sketch shows a painter’s scaffold in mechanical equilibrium. The person in the middle weighs 500 N, and the tensions in each rope are 400 N. What is the weight of the scaffold?

Solution: The below figure shows the middle the person standing weights is 500 N, The tension in the each rope is 400 N, We need to find the weight of the scaffold We see there is a total tension of each rope is 400 N + 400 N = 800 N 800 N pulling up and the total of 500 N + W pulling down. The net force is ero, because the system is in equilibrium. This means that the force down must equal the force UP, 500 N + W = 800 N We need to find the weight so rearrange the above equation as, W = 800 N - 500 N W = 300 N. Therefore, the weight of the scaffold W is 300 N.