posted by Bella on .
A man of mass 64.8 kg stands on a scaffold supported by a vertical rope at each end. The scaffold has a mass of 16.8 kg and is 3.9 m long. Suppose the man stands to the right from the middle of the scaffold that is a distance one sixth of the length of the scaffold. What is the tension in the right rope?
The man stands 3.9/6=0.65m to the right of the centre of the scaffold.
Let the tensions be L and R respective for the left and right ropes.
Sum moments about the left end:
16.8*1.95+64.8*(1.95+0.65) - R*3.9 = 0
Solve for R.
where is the 1.95 coming from?
1.95=3.9/2 (half of the length, at the centre of gravity of the plank).