Height of Q from P is 2R
Kinetic energy = potential energy
12mv2o≥mg(2R)
vo≥2√gR
Hence, minimum horizontal velocity is 2√gRms−1
A small block of mass m is lying at rest at point P of a wedge having a smooth semi circular track of radius R. The minimum value of horizontal acceleration ao of wedge so that mass can just reach the point Q?