A leak proof cylinder of length 1m, made of
a metal which has very low coefficient of
expansion is floating vertically in water at 0°C
such that its height above the water surface is
20 cm. When the temperature of water is
increased to 4°C, the height of the cylinder
above the water surface becomes 21 cm. The
density of water at T = 4°C, relative to the
density at T = 0°C is close to :