A railroad car of mass 2.45 104 kg is moving with a speed of 3.96 m/s. It collides and couples with three other coupled railroad cars, each of the same mass as the single car and moving in the same direction with an initial speed of 1.98 m/s. (a) What is the speed of the four cars after the collision

2.475m/s

Explanation:

The computation of speed of the four cars after the collision is shown below:-

Now we will say that as per the law of conservation of momentum, the initial and the final momentum of cars is having same masses before and after collision is same and the equation will be

=

= 2.475m/s

Therefore we simply applied the above formula to reach out the speed of the four cars after the collision.

that would be because of both gravity and friction. so     c