In an air heating system, heated air at 40°c and 105 kpa absolute is distributed through a 0.2 m × 0.3 m rectangular duct made of commercial steel at a rate of 0.5 m3/s. determine the pressure drop and head loss through a 30-m-long section of the duct. the roughness of commercial steel surfaces is ε = 0.45 m. the dynamic viscosity of air at 40°c is μ = 1.918 × 10–5 kg/m·s, and it is independent of pressure.

Anonzero net force acts on a particle and does work. which one of the following statements is true? the kinetic energy of the particle changes, but the speed of the particle does not change. the kinetic energy of the particle does not change, but the speed of the particle does change. the kinetic energy of the particle changes, but the velocity of the particle does not change. the kinetic energy and the speed of the particle change, but the velocity of the particle does not change. the kinetic energy, speed, and velocity of the particle change.