1. A gas flows with a velocity v along a pipe of cross-sectional area S and bent an angle of $(90^{\\circ})$ at a point A . What force does the gas exert on the pipe at A if its density is $(\rho)$ ?
(1) $(\frac{\sqrt{2} S v}{\rho})$
(2) $(\sqrt{2} S v^{2} \rho)$
(3) $(\frac{\sqrt{3} S v^{2} \rho}{2})$
(4) $(\sqrt{3} S v^{2} \rho)$