Two objects each of mass 5 kg are moving in the same straight line but in the opposite direction towards each other with some speed of 3 m/s. They stick to each other after collision. What will be the velocity of the combined object after collision?

Explanation

Before collision,
`m_(1)=m_(2)=5kg`
`u_(1)=3m//s`
`u_(2)= -3m//s`
At collision,
After collision,
Let the velocity of the combined object be v.
Total momentum before collision is
`m_(1)u_(1)+m_(2)u_(2)=5xx3+5xx(-3)=0`
Total momentum of the system after collision is
`m_(1)v +m_(2)v=(m_(1)+m_(2))v=(5+5)v=10v`
According to the conservation of momentum,
Momentum before collision = Momentum after collision
`therefore 0 = 10v`
`therefore v =0`
Hence, the velocity of the combined object after collision is zero.