# A 20 kg ball moving with a velocity 6 ms−1 collides with a 30 kg ball initially at rest .if both of them coalesce ,then final velocity of the combined mass is

Question: A 20 kg ball moving with a velocity 6 ms−1 collides with a 30 kg ball initially at rest .if both of them coalesce ,then final velocity of the combined mass is

(A) $6ms^{-1}$

(B) $6ms^{-1}$

(C) $3.6ms^{-1}$

(D) $2.4ms^{-1}$