Momentum is an important idea in events where no outside forces are acting. Let's break this down into simpler parts.

1. Conservation of Momentum:

   • In a closed system, which means nothing is getting in or out, the total momentum before something happens (like two cars crashing) is the same as the total momentum after.
   • We can think of it like this:
   • Total momentum before = Total momentum after.

2. Impulse and Change in Momentum:

   • When a force acts on an object for a certain amount of time, it causes a change in that object's momentum.
   • In simpler terms, the push (or force) times the time it was applied equals the change in momentum.

3. Types of Collisions:

   • In elastic collisions, both momentum and kinetic energy (the energy of moving things) are kept the same.
   • In inelastic collisions, momentum is still conserved, but some of the kinetic energy turns into other types of energy.
   • For instance, in real-life crashes, about 90% of the time, kinetic energy gets changed into other forms, showing us how elastic and inelastic collisions are different.

By understanding these concepts, we can better grasp how things move and interact in our world!