Question

The diameter of a roller is $84cm$ and its length is $120cm$. It takes $500$ complete revolutions to move once over to level a playground. Find the area of the playground in $m^2$.

Answer 1

REF.Image.

Radius of roller $=42cm$

Length $=120cm$

Roller will move along its curved surface area.

$CSA=2\pi rh=2\times \frac{22}{7}\times 42\times 120=31680c{m}^2$

$\therefore$ Area covered by one revolution $=31680c{m}^2$

$\therefore$ Area covered by 500 revolutions $=500\times 31680$

$=15840000c{m}^2$

$\therefore$ Area of the playground in $m^2=\frac{15840000}{10000}{m}^2$

$=1584m^2$