Question

A ball of mass 200gm. And another of 300 gm . move towards each other with speed of 12m/s and 3m/s respectively . if they stick to each other after colliding , what be the velocity of the combined mass after collision.

Answer 1

Data:
Mass of ball 1 = m1 = 200 g = 0.2 kg
Mass of ball 2 = m2 = 300 g = 0.3 kg
Velocity of ball 1 = V1 = 12 m/s
Velocity of ball 2 = V2 = 3 m/s
Velocity of the combined mass after collision = V = ?
Solution:
Momentum of the system before collision = m1V1 + m2V2
                                                                  = (0.2) (12) + (0.3) (3)
                                                                  = 2.4 + 0.9
                                                                  = 3.3 kg m/s
Now,
Combined mass = m = m1 + m2
                              m = 0.2 + 0.3
                              m = 0.5 kg
Since momentum is conserved,
So, Total momentum before collision = Total momentum after collision
⇒ 3.3 = mV
⇒ 3.3 = (0.5) V
⇒ 3.3/0.5 = V
⇒ V = 6.6 m/s
Which shows that the velocity of the combined mass after collision = 6.6 m/s