Saved Bookmarks
| 1. |
Water is pumped from a storage tank through a tube of 3.0 cm inside diameter at the rate of 0.001 m^3 /s. What is the kinetic energy per kg water in the tube?(a) 2.00 J/kg(b) 1.00 J/kg(c) 5.00 J/kg(d) 0.05 J/kg |
|
Answer» The correct option is (b) 1.00 J/kg To explain I would say: Kinetic energy Ek = mv^2, tube dia. D = 3.0 cm, m = 1 kg. Cross-section area of tube A = (frac{1}{4}) πD^2 = (frac{1}{4}) π(3.0/100 m)^2 = 7.0686×10^-4m^2 Average velocity of water v = Q/A = 0.001 m^3 /(7.0686×10^-4m^2) = 1.415 m/s KE per kg = Ek/m = 1/2 v^2 = 1/2 (1.415 m/s)^2 = 1.00 m^2/s^2 = 1.00 J/kg. |
|