# centre of mass

Two children Tony and Chris of same mass $$M$$ (including their caps) are sitting on either end of a see saw. Initially, the beam is horizontal. At once, Chris throws away his cap (of mass $$M/25$$) which falls at point $$Q$$, midpoint of the left half of the beam, due to this the balance of beam is disturbed. To balance it again we must put a mass $$m$$ at point $$P$$, which is located halfway from the balance point to the right end of the beam.

What is $$m/M$$?

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