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Question
An iron pole consisting of a cylindrical portion 110 cm high and of base diameter 12 cm is surmounted by a cone 9 cm high. Find the mass of the pole, given that 1 cm3 of iron has 8 gm of mass (approx). (Take π = `355/113`)
Solution
Radius of the base of poles (r) = 6 cm
Height of the cylindrical part (h1) = 110 cm
Height of the conical part (h2) = 9 cm
Total volume of the iron pole
= `pir^2h_1 + 1/3pir^2h_2`
= `pir^2(h_1 + 1/3h_2)`
= `355/113 xx 6 xx 6(110 + 1/3xx9)`
= `355/113 xx 36 xx 113`
= 12780 cm3
Weight of 1 cm3 = 8 gm
Therefore, total weight = 12780 × 8
= 102240 gm
= 102.240 kg ...`[∵ 1 gm = 1/1000 kg]`
= 102.24 kg
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