Question

A small block of mass M moves on a frictionless surface of an inclined plane , as shown in figure.The angle of the incline suddenly changes from 60${}^o$ to 30${}^o$ at point B .The block is initially at rest at A .Assume that collisions between the block and the incline are totally inelastic (g =10m/s${}^2$)

Answer 1

Along the plane velocity just before collision $V=\sqrt{2g\left(3\right)}=\sqrt{60}m/s$

Along the plane velocity after collision $V_B=V\cos {30}^0=\sqrt{45}m/s.$