Question

A cylinderical rod whose height is 8 times of its radius is melted and recast into spherical balls of same radius. The number of balls will be

• A. 4
• B. 3
• C. 6
• D. 8

Answer 1

The correct option is C

6

Let r be th radius of a cylindrical rod = r

then its height $\left(h\right)=8r$

$\therefore Volume=\pi r^{2}h=\pi r^2\times 8r=8\pi r^3$

Radius of spherical ball = r

$\therefore$ Volume $=\frac{4}{3}\pi r^3$

Number of balls$=\frac{Totalvolume}{Volumeofoneball}$

$=\frac{8\pi r^3}{\frac{4}{3}\pi r^3}$

$=\frac{8\times 3}{4}$ = 6