7. Water flows with a velocity of 6 m/s through 6 m of cast-iron pipe (roughness = 0.0003 m). The pipe has an inside diameter of 43 mm. The kinematic viscosity of the water is 1.00x10 m2/s. The resistance coefficient for the standard elbow is 0.9. What percentage of the total head loss is caused by the elbow? 3.5 m C= 0.9 6 m/s- A. 4.86%; B. 6.27%; C. 8.83%; D. 15.60%. 2.5 m