When the energy balance on the fluid in a stream tube is written in the following form, it is known as Bernoulli’s equation:
P2 P1 þ gðz2 z1Þ þ 2 ðV2 2 V2 1 Þ þ ef þ w ¼ 0
where w is the work done on a unit mass of fluid, ef is the energy dissipated by friction in the fluid per unit mass, including all thermal energy effects due to heat transfer or internal generation, and is equal to either 1 or 2 for turbulent or laminar flow, respectively. If P1 ¼ 25 psig, P2 ¼ 10 psig, z1 ¼ 5 m, z2 ¼ 8 m, V1 ¼ 20 ft/s, V2 ¼ 5 ft/s, ¼ 62:4 lbm/ft3 , ¼ 1, and w ¼ 0, calculate the value of ef in each of the following systems of units:
(a) SI
(b) mks engineering (e.g., metric engineering)
(c) English engineering
(d) English scientific (with M as a fundamental dimension)
(e) English thermal units (e.g., Btu)
(f ) Metric thermal units (e.g., calories)