$2\mathrm{.}34.$ Water at $20C$ flows at $6\frac{L}{s}$ through a $75mm$ diameter pipe, and a fixture is installed such that the diameter is suddenly reduced to $50mm.($a$)$ Estimate the head loss due to the sudden contraction. $($b$)$ What pressure change is expected at the contraction? $($c$)$ What would be the pressure change if the local head loss is not taken into account?