Formula:
The formula is D²L/162
Where,
D = Diameter of steel bar in millimetre
L = Length of steel bars in meter
Solution:
We know that,
Weight= Cross sectional area x Length x Density
For steel bar, this also remains same.
The weight of steel bars= Cross sectional area of steel bar x Length of steel bar x Density of steel bar.
That means,
W = A x L x ρ
Where,
W = Weight of steel bars
A = Area = πD²/4
π (pi) = 3.14
D = Diameter of steel bar in millimeter
L = Length of steel bar in meter
ρ (Rho) = Density of steel bar = 7850 kg/m³
Therefore,
W = 3.14 x D²/4 x L x 7850
But there is two conflicting unit in the formula. Which is millimetre for D and meter for ρ (Rho).
So we need to convert either D or ρ to the same unit.
Let’s change the unit of D from millimetre to meter.
1 millimetre = 0.001 meter
Let’s put this into the formula,
W= 3.14 x {(D² x 0.001 x 0.001)/4} x L x 7850
= D²L/162
Result:
D²L/162
