Question:

Where is the bird’s centre of gravity?

Answer:

There are weights cleverly planted in the tips of the wings. This brings the centre of gravity of the bird to be just BELOW its beak.

Two things to note:

(1)

The C.G. of a body can lie OUTSIDE the body.

(2)

It is important for the C.G. to be BELOW the beak in order for this toy to work. With the CG below the pivot, the weight of this bird always provides a restoring torque when the bird is displaced from its equilibrium position. If the C.G. was exactly at the beak, the bird would be having an unstable equilibrium.

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