* Momentum is the measure of an object's mass in motion. It's calculated as:

Momentum (p) = mass (m) × velocity (v)

* Decreasing Velocity: If the velocity of an object decreases, while its mass remains constant, the product of mass and velocity (which is momentum) will also decrease.

In simpler terms:

Imagine a heavy truck rolling down a hill. The truck has a lot of momentum because it's big and moving fast. As it reaches the bottom and starts slowing down, its momentum decreases because it's not moving as quickly anymore.