Two particles released from the same height and reached the base at the same time

Problem
Particles A and B are elevated 12 meters high from a given reference base. Particle A is projected down an incline of length 20 meters at the same time particle B is let to freely fall vertically. Find the velocity of projection of particle A if both particles strikes the base at the same time.
 

Kinematics

Motion of a Particle
Particle is a term used to denote an object of point size. A system of particles which formed into appreciable size is termed as body. These terms may apply equally to the same object. The earth for example may be assumed as a particle in comparison with its orbit, whereas to an observer on the earth, it is a body with appreciable size. In general, a particle is an object whose size is so small in comparison to the size of its path.