# Two objects of masses 100g and 200g are moving along the same line and direction with velocities of 2 ms -1 and 1 ms -1

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Two objects of masses 100g and 200g are moving along the same line and direction with velocities of 2 ms -1 and 1 ms -1 , respectively. They collide and after the collision, the first object moves at a velocity of 1.67 ms -1 . Determine the velocity of the second object.

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Mass of one of the objects, m1 = 100 g = 0.1 kg

Mass of the other object, m2 = 200 g = 0.2 kg

Velocity of m1 before collision, v1 = 2 m/s

Velocity of m2 before collision, v2 = 1 m/s

Velocity of m1 after collision, v3 = 1.67 m/s

Velocity of m2 after collision = v4

According to the law of conservation of momentum:

Total momentum before collision = Total momentum after collision

m1v1 + m2v2 = m1v3 + m2v

⇒ 0.1×2 + 0.2×1 = 0.1×1.67 + 0.2×v4

⇒ 0.4 = 0.67 + 0.2×v4

⇒ v4 = 1.165 m/s

Hence, the velocity of the second object becomes 1.165 m/s after the collision.