Question

A 0.75 kg board of length 2.60 m initially rests on two supports as shown. What maximum distance, x, from the right-hand support can a 1.20 kg bird walk before the board begins to leave the left-hand support

Answer 1

By equilibrium of torques:

$$mgx=Mgl→x=Ml/m=0.75·0.5/0.31\text{ m}.$$