An object of mass 2 kg is moving with a velocity of 3 m/s and collide head-on with an object B of mas 1 kg moving in the opposite direction with a velocity of 4 m/s. After collision both objects coalesce so that they move with a common velocity v equal to

• A

  1 m/s

• B

  2 m/s

• C

  3 m/s

• D

  $\frac{2}{3} \mathrm{m}/\mathrm{s}$