Question

A particle is projected with a certain velocity at an angle  above the horizontal from the foot of an inclined plane of inclination 30o. if the particle strikes the plane normally then  is equal to

Answer 1

For particle is projected with a certain velocity at an angle theta above the horizontal is given as:
A = 45 – B/2
where
A is the angle at which it is projected from the surface of inclined plane and B is the angle of inclined plane.
here, B = 45 degree.
therefore, A = 45 -45/2 = 45/2 degree.
or 22.5 degree.