Two objects of masses 100 g and 200 g 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 m s-1. Determine the velocity of the second object.

For this, firstly we have to calculate the total momentum of both the objects:

Momentum of first object:


= Mass of first object × Velocity of first object


= kg × 2 m/s


= 0.1 kg × 2 m/s


= 0.2 kg m/s


Momentum of second object:


= Mass of second object × velocity of object


= kg × 1 m/s


= 0.2 kg × 1 m/s


= 0.2 kg m/s


Total momentum = Momentum of first object + Momentum of second object


= 0.2 + 0.2


= 0.4 kg m/s


It is given that after the collision, the velocity of first object becomes 1.67 m/s


Momentum after collision (First object):


= kg × 1.67 m/s


= 0.1 kg × 1.67 m/s


= 0.167 kg m/s


Let, the velocity of second object after the collision be v m/s


Momentum after collision (Second object)


= kg × v m/s


= 0.2 kg × v m/s


= 0.2v kg m/s(ii)


Total momentum of the objects after collision = 0.167 + 0.2 v


We know that,


According to the law of conversion of momentum:


Total momentum before collision = Total momentum after collision


0.4 = 0.167 + 0.2 v


0.2 v = 0.4 – 0.167


0.2 v = 0.233


v =


v = 1.165 m/s


Therefore, the velocity of second object will be 1.165 m/s


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