Considering plane along Wedge axis,when particle collides with the plane, its component of velocity parallel to inclined plane should be zero.\\\\(\\Rightarrow u \\cos\ heta - g \\sin\ heta \ imes t =0\\\\) {Equation along the plane}\\\\(t=\\displaystyle \\dfrac { u }{ g \ an \ heta } \\\\)\\\\(u=\\displaystyle gt\ imes \ an\ heta = \\dfrac{gt}{\\sqrt{3}}\\\\)Now, Consider the plane along original x-y axis,Thus,Horizontal displacement before it hits the plane \\\\(=ut\\\\)vertical displacement during the time t \\\\(=\\dfrac{1}{2} g t^2 \\\\)Now , \\\\( \ an 30^\\circ{} =\\displaystyle \\dfrac{ h- \\frac{1}{2} g t^2 } { ut }\\\\)\\\\( \\dfrac{1}{\\sqrt{3}} = \\displaystyle \\dfrac{ h- \\dfrac{1}{2} g t^2 } { ut }\\\\)Hence , \\\\( \\dfrac{1}{3} = \\displaystyle ( \\dfrac{h} {gt^2} - \\dfrac{1}{2} ) \\\\)\\\\(t=\\displaystyle \\sqrt{ \\dfrac{6h}{5g}} \\\\) Hence , \\\\(t = 2.5938 \\\\) sSo,\\\\(u = gt \\, \ an 30^\\circ{} = \\displaystyle \\dfrac{9.8 \ imes 2.5938}{\\sqrt 3} = 14.69 \\simeq 10 \\sqrt{2}\\\\) m/s