Question

A horizontal jet strikes a frictionless vertical plate (the plan view is shown in the figure). It is then divided into two parts, as shown in the figure. If the impact loss is neglected, what is the value of $\theta$ ?

• A. 15${}^{\circ }$
• B. 30${}^{\circ }$
• C. 45${}^{\circ }$
• D. 60${}^{\circ }$

Answer 1

The correct option is B 30${}^{\circ }$

From continuity equation, we get

$Q_0=Q_1+Q_2$

$\Rightarrow Q_0=0.25Q_0+Q_2$

$\Rightarrow Q_2=0.75Q_0$

Since, the impact losses are neglected, the velocity will remain unchanged in the direction of $Q_1$ and $Q_2$

i.e., $V_0=V_1=V_2$

Applying impulse momentum equation, we get

$\rho Q_0{V}_{0}sin\theta =\rho Q_2{V}_2-\rho Q_1{V}_1$

$\Rightarrow Q_{0}sin\theta =0.75Q_0-0.25Q_0$

$\Rightarrow sin\theta =1/2$

$\Rightarrow \theta ={30}^{\circ }$