Answer:

Explanation:
<u>Conservation of Momentum
</u>
The total momentum of a system of two particles is

Where m1,m2,v1, and v2 are the respective masses and velocities of the particles at a given time. Then, the two particles collide and change their velocities to v1' and v2'. The final momentum is now

The momentum is conserved if no external forces are acting on the system, thus

Let's put some numbers in the problem and say



120=120
It means that when the particles collide, the first mass returns at 6 m/s and the second continues in the same direction at 28 m/s
The law says things travel in a straight line at constant speed unless acted upon by a force. But friction is a force but it can't be seen easily other than its effect, which is to bring the object to rest in seeming violation of the 1st law.