While playing football match, Kris collided and got entangled with Tom who was playing for opposite team and running from opposite side. The mass of Kris was 40 kg and the mass of Tom was 60 kg. If Tom was running with a velocity of 3m/s and Kris was running with a velocity of 4 m/s, find the velocity and direction of both of the players after collision assuming other forces were negligible.

Here,
Mass of Kris, $m_1=40 kg$
Initial velocity of Kris, $u_1=4 m/s$
Mass of Tom, $m_2=60 kg$
Initial velocity of Tom, $u_2=3 m/s$
Final velocity and direction of both of the player after collision $=?$
Let final velocity of both of the players after collision $=v$
Let Kris was coming from left and Tom was coming from right.
Let the velocity of Kris is positive, therefore velocity of Tom will be negative as both were running in opposite directions.
Thus, initial velocity of Kris, $u_1=4 m/s$
And the initial velocity of Tom, $u_2=-3 m/s$
From the law of conservation of momentum, we know that,
                                                                                           $m_1{u}_1+m_2{u}_2=m_1{v}_1+m_2{v}_2$
When two bodies stick to each other after collision, the collision is said to be perfectly inelastic and in this case the two bodies do not push each other and continue to move with the same velocity with their deformed shape after collision. Here, Tom and Krish got entangled after collision, so they will get the same velocity after collision. Thus,
                                                                                         $m_1{u}_1+m_2{u}_2=m_{1}v+m_{2}v$

                                                                     or,              $40\times 4+60\times (-3)=40\times v+60\times v$

                                                                     or,                $160-180=v(40+60)$

                                                                     or,                $-20=v\left(100\right)$

                                                                     or,                  $v=\frac{-20}{100}=-0.2 m/s$

Negative velocity shows that both the player would go from right to left after collision, with the same velocity of $-0.2 m/s$.