Question

The diameter of a roller is 84 cm and it’s length is 120 cm . it takes 500 revolutions moving once over a level playground . what is area of playground ?

Answer 1

Here's your answer mate!

Diameter=84cm..

So Radius =84/2 cm
=42cm

Length = 120cm

So the curved surface area will be...

Length × circumference

= 120 ×(2π r)
= 240× 3.14× 42
$= 31651.2 \: \: {cm}^{2}$
Now,

if it revolves once
It will cover an area= 31651 cm^2


If it rolls 500 times then it will cover an area =
$500 \times 31651.2 \: \: {cm}^{2}$

=
$15825600 \: {cm}^{2} \\ \\ = 1582.56 \: {m}^{2}$
Hope i answered well.

Answer 2

Answer:

Height of roller = Length of roller = 120 cm

Radius = $\dfrac{84}{2}$ = 42 cm

$\\ \large{ \boxed{ \sf { \green{ \: curved \: \: surface \: \: area \: \: of \: \: a \: \: cylinder = 2\pi \: rh}}}} \\ \\ \\ \implies \sf \bigg(2 \times \frac{22}{7} \times 42 \times 120) \: \: {cm}^{2} \\ \\ \\ \implies \sf \: 31680 \: \: {cm}^{2}$

Area of field = 500 × C.S.A of radius

$\\ \implies \sf \: (500 \times 31680) \: \: {cm}^{2} \\ \\ \\ \implies \sf \: 15840000 \: \: {cm}^{2} = \frac{1584000}{10000} \\ \\ \ \ \implies \sf \: 1584 \: \: {m}^{2}$