21A ball is projected on smooth inclined plane in direction perpendicular to line of greatest slope means that ball is projected horizontally (since line of max slope is vericle line with slope infinity)
as the ball is projected on the incline plane horizontally it bouces up at some angle to the plane.....plane being smooth and collision elastic.....therfeore angle made by initial direction of ball with teh plne is same as angle made by teh ball's direction after collision and since collision is elastic mag of vel also remains same as 8m/s....which now follows a parablic path.......
so the thing is it is same as ball being projected at an angle of 37 degree with the incline on the plane with speed 8m/s and u hav to find its speed after 1 sec
now rest is easy ....do on ur own