Question

Two object of masses 100g and 200g are moving along the same line and direction with velocities of 2m/s and Im/s respectively. After collision the first object moves at a velocity of 1.67 m/s. Determine the velocity of second object.​

Answer 1

Answer:

Before Collision After collision

A B A B

100 g 200g → 100g 200g

2m/s 1m/s v=? 1.67ms

−1

Let the 100 g and 200 g objects be A and B as shown in above figure.

Initial momentum of A=

1000/100×2=0.2kgms−1

Initial momentum of B=

1000/200×1=0.2kgms−1

∴ Total momentum of A and B before collision

=0.2+0.2=0.4kgms−1

Let the velocity of A after collision =v

∴ Momentum of A after collision =

1000/100×v=0.1v

Also, momentum of B after collision

= 1000/200×1.67=0.334kgms−1

∴ Total momentum of A and B after collision

=0.1×v+0.334

Using the law of conservation of momentum, momentum of A and B after collision = momentum of A and B before collision

0.1×v+0.334=0.4

0.1×v=0.4−0.334

⇒v= 0.066/0.1

v =0.66ms−1