N-identical spheres are placed on the smooth surface touching each other in a straight line. an another identical sphere moving with velocity u along the straig

n-identical spheres are placed on the smooth surface touching each other in a straight line. An another identical sphere moving with velocity u along the straight line hits the sphere. Ife = 1/2 is the co-efficient of restitution between any two spheres, the velocity of the nth sphere is- O 1 2 3 -- [31 7n-1 (a) 37" (b) -1 (c) (d) zero