Question

A medicine capsule is in the shape of a cylinder with two hemisphere stuck to each of its ends as shown in figure. The length of the entire capsule is $14mm$ and the diameter of the capsule is $5mm$. Find its surface area.

Answer 1

For cylindrical part, we have

Radius $=r=\frac{5}{2}mm=2.5mm$

Height $=h=2.5mm$
Length $=(14-(2.5+2.5\left)\right)mm=9mm$

$S_1$ curved surface area of the cylindrical part
$\Rightarrow S_1=2\pi rh=2\times \frac{22}{7}\times 2.5\times 9{mm}^2$

For two hemispheral parts we have
Radius $=r=2.5mm$

Curved surface area of two hemispherical parts $=2\times 2\pi r^2=2\pi r^2=4\times \frac{22}{7}\times {\left(2.5\right)}^2{mm}^2$

Hence surface area of the capsule $=2\times \frac{22}{7}\times 2.5(9+2.5){mm}^2=220{mm}^2$