On a see saw, two chlidren of masses of 30kg and 50kg are sitting on one side of at distances 2m and 2.5m respectively from its middle. Where should a man of mass 74 kg sit to balance it?

On a see saw, two chlidren of masses of 30kg and 50kg are sitting on o

1.	On a see saw, two chlidren of masses of 30kg and 50kg are sitting on one side of at distances 2m and 2.5m respectively from its middle. Where should a man of mass 74 kg sit to balance it?
Answer» Solution :Let two children be sitting on the LEFT ARM. They will produce anticlockwise moment due to their weights about the middle point of SEE saw. total anticlockwise moment `=30Kgf TIMES 2m+ 50Kgf times 2.5m` `=60Kgf times m+125 kgf times m=185 kgf times m` To balance, it the man should sit on the right arm so as to produce a clockwise moment about the middle point. Let his distance from the middle be x m. THen Clockwise moment =`74 kgf times xm=74x kgf times m` By the principle of m= moments, in equilibrium Anticlockwise moment= Clockwise moment `185=74x` or `x= 185/74 m=2.5 m` (on the other SIDE)