n smooth identical spheres are placed in a row and their masses are in the ratio 1:3:9:_________:3ⁿ⁻¹ . Coefficient of restitution between any two successive collisions in 1/3. If first sphere is projected with a velocity v towards the second sphere, then calculate the velocity of the last sphere after (n-1)tℎ sphere strikes it.
a.v/ 3ₙ
b.3ⁿv
c.v/3ⁿ⁻¹
d.3ⁿ⁻¹ᵥ