Water enters the 4inch line at an average velocity of 6 ftse

Solution

we apply continuity equation

a1v1 +a2 v2 = a3 v3 1 repesent 4-inch line .2 represents 6-inch line 3 represents 5 inch line

A is proportion to square of diameter

hence

6*4*4 + 3*6*6 = v *5*5

v = 204/25 = 8.16

hence option c )8.2 is correct

flow rate = area *velocity {flow rate in 10 inch diameter piper will be equal to 5 inch dia due to continuity equation}

= /4 d²*v

= /4 *5*5*8.16 =160.22 inch²feet/sec

= 160.22 * 0.0833 inch³/sec = 13.35 inch³/sec