A particle is projected horizontally with speed u from point A, which is 10 m above the ground. If the particle hits the inclined plane perpendicularly at point B. [g = 10 m/s2](a) Find horizontal speed with which the particle was projected.(b) Find the length OB along the inclined plane.

Dear student,

First of all, draw a neat diagram first of all showing the positon of wedge and motion of projectile and various heights mentioned in problem.
Choose an appropriate coordinate axes (in this case, choose your x-ais along the wedge and y-axis perpendicular to it )and write equations of motion.
Get various parameters you want using these equations.

Thanks