A right circular cylindrical tunnel of diameter 2 m and length 40 m is to be constructed from a sheet of iron. The area of the iron sheet required in $m^{2}$ , is

(a) 40 $π$ (b) 80 $π$

(c) 160 $π$ (d) 200 $π$

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Solution

Diameter of a cylindrical tunnel = 2 m

$∴$ Radius (r) $= \frac{2}{2} = 1$ m

and length (h) = 40 m

Curved surface area = $2 π$ r h

= $2 \times π \times 1 \times 40 = 80 π$

Hence the correct answer is (b) 80 $π$

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A right circular cylindrical tunnel of diameter 2 m and length 40 m is to be constructed from a sheet of iron. The area of the iron sheet required in m2, is (a) 40 π (b) 80 π (c) 160 π (d) 200 π

Diameter of a cylindrical tunnel = 2 m ∴ Radius (r) =22=1 m and length (h) = 40 m Curved surface area = 2π r h = 2×π×1×40=80π Hence the correct answer is (b) 80 π

A right circular cylindrical tunnel of diameter 2 m and length 40 m is to be constructed from a sheet of iron. The area of the iron sheet required in $m^{2}$ , is

(a) 40 $π$ (b) 80 $π$

(c) 160 $π$ (d) 200 $π$

Diameter of a cylindrical tunnel = 2 m

$∴$ Radius (r) $= \frac{2}{2} = 1$ m

and length (h) = 40 m

Curved surface area = $2 π$ r h

= $2 \times π \times 1 \times 40 = 80 π$

Hence the correct answer is (b) 80 $π$