Question

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 $2.5$m $s^{-1}$ before the collision during which they stick together. What will be the velocity of the combined object after collision?

Answer 1

Given : $m_1=m_2=1.5kg$

$u_1=2.5{ms}^{-1}$

$u_2=2.5{ms}^{-1}$

Total mass of the combined system, $M=m_1+m_2=2\times 1.5=3kg$

Let the velocity of the combined system after the collision be $v$

Applying conservation of momentum before and after the collision :

$m_1{u}_1-m_2{u}_2=Mv$

$1.5\times 2.5-1.5\times 2.5=3v$

$⟹v=0$