All planets are spherical, why are they not cubical or cylindrical?

N solid metalic spherical balls are melted and reast into a cylindrical rod whose radius is 3 times that of a spherical ball and height is 4 times the radius of a spherical ball. The value of N is

A water tank, open at the top, is hemispherical at the bottom and cylindrical above it. The radius is 12 m and the capacity is 3312 pi m^(3) . The ratio of the surface areas of the spherical and cylindrical portions is

The bulb of a thermometer is spherical and that of another is cylindrical Equal quantity of mercury is filled in them Then .

Two full tanks, one shaped like a cylinder and the other like a sphere, contain crude oil. The cylindrical tank holds 600 m3 more than the spherical tank. After 400 m3 of crude has been taken out from each tank the cylindrical tank contains twice the amount of oil than in the spherical tank. How many cubic meters of oil did the cylindrical tank have when it was full?

(True/False): Thermometers with spherical bulbs are more sensitive than the thermometers with cylindrical bulbs.

Statements: All planets are stars All stars are asteroids All asteroids are moons Some moons are rocks Conclusions: I. All asteroids are planets II. All asteroids are stars III. All moons are stars IV Some rocks are stars