Question

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

Answer 1

Diameter=84cm
Radius=42cm
Length=120cm
Area of cylinder =2×22/7×42×120cm^2
=44×6×120cm^2
44×270cm^2
=31680cm^2
For 500round=31680×500cm^2
=15840cm^2

Answer 2

Answer:

${\huge{\underline{\underline{\sf{\blue{Solution :-}}}}}}$

The length of the roller is 120 cm , i.e.,

$h = 120 cm = 1.2 m \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: (1 \: cm \: = \: \frac{1}{100} \: m)$

The diameter of the roller = 84 cm

So, radius of the roller (r)

$= \frac{84}{2} cm = 42cm = 0.42m$

Distance covered by the roller in one revolution

= Curved surface area of the roller

$= 2\pi \: rh \: sq. \: units$

$= 2 \times \frac{22}{7} \times 0.42 \times 1.2 \: m^{2}$

$= \: 3.168 \: m \: ^{2}$

Area of the playground = Distance covered by the roller in 500 revolutions

= 500 × 3.168

$= 500 × 3.168 \: m^{2} = 1584 \: m ^{2}$