Q. Calculate the density, specific weight and weight of one litre of petrol of specific gravity = 0.7.
SOLUTION:
Volume 1 litre = 1 x 1000 cm³ =1000/10^6= 0.001m³
Sp. gravity S =0.7
(1) DENSITY
Density (p) = S x 1000 kg/m³
= 0.7 x 1000= 700 kg/m³
(II) SPECIFIC GRAVITY (W)
w =ρ *g
= 700 * 9.81N m ^ 3
= 6867 N/m³ ( g taken as = 9.81kgm³)
(III) WEIGHT (W)
We know that specific weight =weight/ Volume
w = W/0.001 * or * 6867
= W/0.001
W = 6867 * 0.001 = 6.867
DEFINITIONS:
MASS :Mass density (or specific mass) of a fluid is its mass per unit volume. It is denoted by a symbol p (rho). In S.I units it is expressed in KN/m³
SPECIFIC WEIGHT:weight (or weight Density) of a fluid is its weight per unit volume. It is represented by a symbol w (or) Y (gama). In S.I units it is expressed in N/m³
SPECIFIC VOLUME:volume of the fluid per unit weight. Thus it is the reciprocal of specific weight It is denoted by u. in Sl units it is expressed in m³/N
SPECIFIC GRAVITY:ratio of specific weight of the fluid to the specific weight of standard fluid. It is dimensionless and has no units.
