If a spherical metal bob of radius 3cm is fully immersed in a cylinder containing water and the water level rises by 1cm, what is the radius of the cylinder?
I. The earth is not spherical but elliptical in shape
II. Variation in latitude and longitude
III. Rotation of the earth on its axis
IV. Variation in the density of the earth
On which combination of the above does the weight of an object vary on the earth's surface?
