V, A F - (1-a)A

A jet of liquid of density ρ and area A strikes a block and
splits into two jets, as in Fig. P3.75. Assume the same
velocity V for all three jets. The upper jet exits at an angle
θ and area α A . The lower jet is turned 90 ° downward.
Neglecting fl uid weight, ( a ) derive a formula for the
forces ( F _x , F _y ) required to support the block against fluid momentum changes. ( b ) Show that F _y = 0 only if α≥ 0.5.
( c ) Find the values of α and θ for which both F x and F y are zero.