Question

A hollow cylindrical iron pipe is $40$cm long.Its outer and inner diameters are $8$cm and $5$cm respectively.Find the volume of the material, and the weight of the pipe if $1$cc of iron weighs $7$gm.

Answer 1

Outer radius$=R=\frac{8}{2}=4$cm

Inner radius$=r=\frac{5}{2}=2.5$cm

Height of the pipe$=40$cm

Volume of the material$=\pi h(R+r)(R-r)$cu.units

$=\frac{22}{7}\times 40(4+2.5)(4-2.5)$cu.cm

$=\frac{22}{7}\times 40\times 6.5\times 1.5$cu.cm

Given: weight of the pipe if $1$cc of iron weighs $7$gm.

$\therefore$ Weight of the hollow cylindrical iron pipe$=\frac{22}{7}\times 40\times 6.5\times 1.5\times 7$cu.cm

$=8580$gms

$=8.58$kgs

Weight of the pipe$=8.58$kgs