A particle is projected onto an incline plane as shown in the figure. The component of velocity perpendicular to the plane when its strikes at A

$$\begin{gathered} V_y=U_y+a_{y}T \\ {U}_y=10\sin {30}^0=5m/s \end{gathered}$$

$a_y=-g\cos {30}^0=-5\sqrt{3}m/s^2$

$$\begin{gathered} \therefore Substitute{u}_{g}and{a}_{y}inequation \\ We get the component of velocity perpendicular to the plane is \\ {\text{v}}_{\text{y}}=\text{ 5m}/\text{sec} \end{gathered}$$

$time of flight = T=\frac{2u\sin (\alpha -\beta )}{g\cos \beta }$

$$\begin{gathered} T=\frac{2\times 10\times \sin 30}{g\cos 30} \\ T=\frac{20\times {\displaystyle \frac{1}{2}}}{10\times {\displaystyle \frac{\sqrt{3}}{2}}} \\ T=\frac{2}{\sqrt{3}} \end{gathered}$$

$V_y=U_y+a_{y}T$

$$\begin{gathered} substitute the obtained values \\ {V}_y=5-5\sqrt{3}\times \frac{2}{\sqrt{3}}=-5m/s \end{gathered}$$