posted by JP .
A 74 kg adult sits at one end of a 8.5 m long board. His 35 kg child sits on the other end.Where should the pivot be placed so that the board is balanced, ignoring the board's mass?
Just take the torque from where the adult sits. So it will be: 0 = (Force of the pivot)*(x) - (25)*(g)*(9). The force of the pivot can be calculated by taking the total force on the board. Which is (the force of the pivot) - (The adult's weight) - (The child's weight).