a hollow iron pipe is 42 cm long and its external diameter is 8 cm . if the thickness of the pipe is 1 cm and iron weighs 3 g / cm 3 , then the weight of the pipe is :
"external radius = 4 cm , internal radius = 3 cm . volume of iron = 22 / 7 x ( ( 4 square ) - ( 3 square ) ) x 42 = ( 22 / 7 ) x 7 x 1 x 42 cm 3 . = 924 cm 3 . weight of iron = ( 924 x 3 ) gm = 2772 gm = 2.772 kg answer : e"
divide(multiply(subtract(volume_cylinder(divide(8, const_2), 42), volume_cylinder(subtract(divide(8, const_2), const_1), 42)), 8), const_1000)