Question

A coal sample having moisture content of 8.0% has unit weight 15.6 kN/m\(^3\). The dry unit weight of the sample, in kN/m\(^3\) is \(\underline{\hspace{1cm}}\). (round off to 2 decimal places)

Hint:

Dry unit weight is always obtained by dividing bulk unit weight by \(1+w\).

Answer 1

Correct Answer: 14

Moisture content is given as 8% which means the dry mass is 92% of the total mass.
Dry unit weight is therefore computed as:
\[ \gamma_d = \frac{\gamma}{1 + w} \] where \( w = 0.08 \).
\[ \gamma_d = \frac{15.6}{1.08} = 14.444\; \text{kN/m}^3 \] Rounded to 2 decimal places:
\[ \boxed{14.44\ \text{kN/m}^3} \]