An iron spherical ball of radius 21 cm is melted and it is re-cast into small hemispheres radius 7 cm each. The number of hemispheres formed will be
Radius of the spherical ball,R=21 cm
Radius of each hemispherical ball,r=7 cm
The volume will remain constant as same volume of iron metal is used to re-cast the hemispherical balls.
Let's assume x such hemispherical balls will be formed.
So, Volume of spherical ball = x × Volume of each hemispheical ball
∴ After re-casting 54 small hemispherical balls are formed.