A man raises a load of 360 kgf using a block and tackle system of 3 pulleys. If the efficiency of the pulley system is 60%, what effort is applied by the man?
Given : L = 360 kgf, E = ?, Efficiency = 60% = 0.6,
Velocity ratio = No of pulleys in the system = 3.
Mechanical advantage (M.A.) = V.R. x Efficiency = 3 x 0.6 = 1.8
But, M.A. = Load(L)/Effort(E)
∴ Effort(E) = Load(L)/M.A.
= 200 kgf.