The volume of the steel bar is the product of the area of the cross-section and the length x r 2 x l 3.1416 x 10 2 x 1000 314,160 mm 3 314.16 cm 3 r 12 x diameter, l 1 m 1000 mm. If using a carbon steel with density of 7.95 gcm 3, we need the product of 7.95 and 314.16, which equals 2497.572 g, or 2.498 kg.