Here's why:

* Momentum is a vector quantity, meaning it has both magnitude (amount) and direction.

* Magnitude: The magnitude of momentum is calculated by multiplying an object's mass (m) by its velocity (v): Momentum (p) = mass (m) x velocity (v)

* Direction: The direction of momentum is the same as the direction of the object's velocity.

So, a heavier object moving at the same speed has more momentum than a lighter object. Similarly, a lighter object moving faster has more momentum than a heavier object moving slower.