i taught this to my ex tuition students before. 2 of them asked
the same question.
at surface:
pressure, P1 = 1atm (atmospheric pressure equivalent to 10m of
water), V1 = 6cm3
at bottom of lake:
pressure, P2 = 3 atm (atmospheric pressure + 20m of water), V2 =
unknown
Using Bolye's Law, P1V1 = P2V2
V2 = 2cm3
