Two objects, each of mass 1.5 kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5 ms-1 before the collision during which they stick together. What will be the velocity of the combined objects after collision?


Given,

Mass of first object, m1 = 1.5 kg


Velocity of first object, v1 = 2.5 m/s


Momentum of first object = m1 × v1


= 1.5 × 2.5


= 3.75 kg m/s


Mass of second object, m2 = 1.5 kg


Velocity of first object, v2 = - 2.5 m/s


So, Momentum of second object, m2 × v2


= 1.5 × (-2.5)


= - 3.75 kg m/s


So, Total momentum = 3.75 + (-3.75)


= 0 kg m/s (i)


Combined mass = m1 + m2


= 1.5 + 1.5


= 3.0 kg


Let, the velocity of the combined objects after collision will be v m/s.


Total momentum = (m1 + m2) × v


= 3.0 × v (ii)


We know that,


According to the principle of conservation of momentum:


Total momentum before collision = Total momentum after collision


0 = 3.0 × v


v =


= 0 m/s


Therefore, the velocity of the combined objects after the collision will be 0 m/s.


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