Here's why:
* Momentum is a measure of an object's mass and velocity. It's calculated by the formula: Momentum (p) = mass (m) x velocity (v)
* When an object stops, its velocity becomes zero.
* Since velocity is a part of the momentum equation, the momentum also becomes zero.
How can an object stop without a collision?
* Friction: This is the most common way. Friction between the object and the surface it's moving on (air resistance, ground friction) will gradually slow the object down.
* External force: An opposing force, such as a brake on a car or a person pushing against the object, can bring it to a stop.
Important Note: Momentum can't be destroyed, only transferred. In the cases above, the momentum of the object is transferred to the surroundings:
* Friction: The momentum is transferred to the surface, causing it to heat up slightly.
* External force: The momentum is transferred to whatever is applying the force (like a brake or a person).
