Circular discs 5mm thickness, are placed one above the other to form a cylinder of curved surface area 462cm². Find the number of discs, if the radius is 3.5cm?
Answers
✯Given✯
➝ Thickness of the disc = 5mm = ⁵⁄₁₀ = 0.5cm
➝ Radius of the disc = 3.5cm
➝ Curved Surface area = 462cm² (2πrh) - (i)
✯To find✯
➝ Number of discs
✬Solution✬
➔ Let the number of discs be x
➔∴ Height of cylinder = h = Thickness of disc × no. of discs
➔∴ Height of cylinder = 0.5 × x
➔ 2πrh = 2 × ²²⁄₇ × 3.5 × 0.5x - (ii)
✭From (i) and (ii) we get✭
➙ 2 × ²²⁄₇ × 3.5 × 0.5x = 462
➙ ∴x = 462 × 7 ÷ 2 × 22 × 3.5 × 0.5
➙ ∴x = 42 discs
✬The number of discs are 42✬
➸Learn more:
- Volume of cylinder = πr²h
- Total surface area of cylinder = 2πr(r+h)
- Curved surface area of cylinder = 2πrh
➔Where:
➺ r is radius
➺ h is height
➺ π is ²²⁄₇
Answer:
✯Given✯
➝ Thickness of the disc = 5mm = ⁵⁄₁₀ = 0.5cm
➝ Radius of the disc = 3.5cm
➝ Curved Surface area = 462cm² (2πrh) - (i)
✯To find✯
➝ Number of discs
✬Solution✬
➔ Let the number of discs be x
➔∴ Height of cylinder = h = Thickness of disc × no. of discs
➔∴ Height of cylinder = 0.5 × x
➔ 2πrh = 2 × ²²⁄₇ × 3.5 × 0.5x - (ii)
✭From (i) and (ii) we get✭
➙ 2 × ²²⁄₇ × 3.5 × 0.5x = 462
➙ ∴x = 462 × 7 ÷ 2 × 22 × 3.5 × 0.5
➙ ∴x = 42 discs
✬The number of discs are 42✬
➸Learn more:
Volume of cylinder = πr²h
Total surface area of cylinder = 2πr(r+h)
Curved surface area of cylinder = 2πrh
➔Where:
➺ r is radius
➺ h is height