Q: A liquid of specific gravity 0.8 is flowing in a pipe line with a speed of 2 m/s. The K.E. per cubic meter of it is

(a) 160 J/m³

(b) 1600 J/m³

(c) 160.5 J/m³

(d) 1.6 J/m³

Ans: (b)

Sol:

K.E per cubic metre

$ \displaystyle = \frac{1}{2}m v^2 /Volume $

$ \displaystyle = \frac{1}{2}\rho v^2 $

$ \displaystyle = \frac{1}{2} \times 0.8 \times 10^3 \times 2^2 $

= 1600 J/m^{3}