M.L Aggarwal book Important Question of class 10 chapter Based on Mensuration for ICSE BOARD.

A cylindrical roller made of iron is 2 m long. Its inner diameter and the thickness is given .

Find the weight of the roller in kg, if 1 cm3 of iron weighs 8 g.

This is the Question Number 22, Exercise 17.1 of M.L Aggarwal.

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# A cylindrical roller made of iron is 2 m long. Its inner diameter is 35 cm and the thickness is 7 cm all round. Find the weight of the roller in kg, if 1 cm3 of iron weighs 8 g.

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This answer was edited.Length of the roller, h = 2 m = 200 cm [1m = 100 cm]Inner diameter = 35 cmInner radius, r = 35/2 cmThickness = 7 cmOuter radius, R = (35/2)+7= (35+14)/2= 49/2 cmVolume of the iron in roller = π(R^{2}-r^{2})h= (22/7)[( 49/2)^{2}-(35/2)^{2}]200= (22/7)[( 49^{2}-35^{2}/4]200= (22/7)×50( 49^{2}-35^{2})= (22/7)×50( 49^{2}-35^{2})= (22/7)×50 (2401-1225)= (22/7)×50×1176= 184800 cm^{3}Given 1 cm³ of iron weighs 8 g.Weight of the roller = 184800×8 = 1478400 g= 1478.4 kg [1 kg = 1000 g]Hence the weight of the roller is 1478.4 kg.