Here's why:
* Momentum is a measure of an object's mass in motion. It's calculated by multiplying the object's mass by its velocity: Momentum (p) = mass (m) x velocity (v).
* Since velocity is a measure of how fast an object is moving *and* in what direction, if an object is stationary (not moving), its velocity is zero.
* Therefore, a stationary object has zero momentum even though it has mass.
Example:
* A car parked in a garage has mass but no momentum because it's not moving.
* A car driving down the highway has both mass and momentum because it's in motion.
Let me know if you have any other physics questions!
