A block of mass m starts moving on a rough horizontal surface with a velocity u. It stops due to friction between the block and the surface after moving through a certain distance. The surface is now tilted to an angle of with the horizontal and the same block is made to go up on the surface with the same initial velocity v. The distance in the mechanical energy in the second situation is smaller than that in the first situation. because
The coefficient of friction between the block and the surface decreases with the increase in the anlge of incliinations.