Question

The radius of a roller is 42 cm and its length is 120 cm. It takes 500 complete revolution to move once over to level a playground determine the area of the playground in metre square​

Answer 1

Given:

• radius of the roller : 42cm
• length of the roller : 120cm
• revolution to move once over to level a playground = 500

To Find:

area of the playground in metre square

Solution:

⊱ Roller is in a form of cylinder

⊱ area of the roller = curved surface of cylinder

area of the roller = 2πrh

$\ = \sf \: (2 \times \frac{22}{7} \times 42 \times 120) {cm}^{2}$

area of the roller = $\tt\underline\red{31680cm²}$

⊱ area of 1 revolution= area of roller = 31680cm²

area of 500 revolution = 500 × 31680cm²

area of playground = 15840000cm²

⊱ area of playground (in metre square)

$\implies \sf \: 15840000 \times \frac{1}{100} \times \: \frac{1}{100} {m}^{2}$

$⟹$$\tt\underline\red{1584m²}$

Hence,

area of the playground is 1584m²

★ $\tt\underbrace\orange{more\: information}$ ★

☆ ғᴏʀᴍᴜʟᴀ ʀᴇʟᴀᴛᴇᴅ ᴛᴏ ᴄʏʟɪɴᴅᴇʀ ☆

1) area of base and top = πr²

2)curved surface area = 2πrh

3)Total surface area= 2πr(h + r)

4)Volume = πr²h

Answer 2

The area of playground is 1584 m^2