Two object, 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 object after collision?

Explanation

Let the two objects are A and B
Mass of object `A,m_1=1.5 kg`
Mass of object `B,m_2=1.5 kg`
Velocity of object A before collision
`u_1=2.5 ms^-1`
Velocity of object B before collision
`u_2=-2.5 ms^-1`
`therefore` Total momentum of object A and B before collision `m_1u_1+m_2u_2`
`=1.5 times 2.5 -1.5 times 2.5=0`
Mass of combined object after collision
`=(m_1+m_2)=3.0 kg`
Let velocity of combined object after collision `=Vms^-1`
`therefore` Total momentum of combined object after collision `=(m_1+m_2) V=(3V) kg ms^-1`
According to the law of conservation of momentum
Momentum after collision= MOmentum before collision
i.e. 3V=0 or V=0