A ball of mass $1 kg$ strikes a wedge of mass $4 kg$horizontally with a velocity of $10 m/s$. Just after collision velocity of wedge becomes $4 m/s$. Friction is absent every where and collision is elastic. Select the correct alternative (s): 

Collision is elastic. Therefore, kinetic energy will be conserved. Let $v$be the speed of ball after collision. Then

$$\begin{gathered} \frac{1}{2}\left(1\right){\left(10\right)}^2=\frac{1}{2}\left(4\right){\left(4\right)}^2+\frac{1}{2}\left(1\right)v^2 \\ or v=6 m/s \end{gathered}$$

Let $J$ be the impulse between the two during collision. Applying impulse$=$ Change in linear momentum 

$$\begin{gathered} J \sin 30°=\left(4\right) \left(4\right) \\ or J=32 N-S \end{gathered}$$