posted by Physics on .
A scaffold of mass 50kg and length 5m is supported in a horizontal position by a vertical cable at each end. A window cleaner of mass 70kg stands at a point 2m from one end. Determine the tension in the nearer cable and also the farther cable.
The sum of the two cable tensions is
T1 + T2 = (M1 + M2)g = 1176 Newtons
M1 = board mass (50 kg)
M2 = cleaner's mass (70 kg)
For the tension T1,set the moment about the other end equal to zero. Let the cleaner be 2 m from cable 1. Take moments about cable 2, 3m from the man
T1*5 = M1*g*2.5 + M2*g*3
T1 = (1/5)*(1225 + 2058) = 657 N
T2 = 1176 - 657 = 519 N