Simple examples for calculating weight are given here.

**1) Calculate the weight of the cast iron rectangular bar as shown in fig. Assume density of cast iron as 0.0072 gm/mm^3.**

**Solution:**

Volume = length x breadth x height

= 100 x 30 x 25

= 75000 mm^3

Hence,

Weight of the rectangular bar= Volume x density of Cast iron

= 75000 x 0.0072

= 540 gm

= 0.54 kg.

**2) Calculate the weight of the mild steel part as shown in fig. Assume density of mild steel as 0.0078 gm/mm^3.**

**Solution:**

Break up the part into four following simple parts as A, B, C & D.

Volume of A = l x b x h

= 60 x 20 x 60

= 72000 mm^3

Volume of B = (π x d^2 x l)/4

= (π x 40^2 x 20)/4

= 8000 π mm^3

Volume of C = (π x d^2 x l)/4

= (π x 25^2 x 30)/4

= 4687.5 π mm^3

Volume of D = (π x d^2 x l)/4

= (π x 15^2 x 70)/4

= 3937.5 π mm^3

Then,

Total Volume = Volume of A + Volume of B + Volume of C – Volume of D

= 72000 + 8000 π + 4687.5 π – 3937.5 π

= 72000 + (8750 π)

= 99492.5 mm^3

Hence,

Weight of the part = Total volume x density of mild steel

= 99492.5 x 0.0078

= 776.0415 gm

= 0.776 kg.