Summary
Highlights
Conservation of momentum states that the total momentum in any closed system remains constant. Momentum is calculated as mass times velocity. Even with multiple objects colliding, the total momentum before and after the collision will stay the same.
Using two balls of equal mass, the video demonstrates that whether one ball is moving and causes the other to move, or they both collide, the total momentum of the system always remains constant. If one has zero velocity and the other has one, momentum is transferred but the total remains the same.
The principle also applies when objects stick together after a collision. If one ball is stationary and another moves towards it and they stick, the total momentum remains the same. The combined object will have half the initial velocity of the moving ball.
Conservation of momentum makes movement on the International Space Station (ISS) challenging. Without handholds, an astronaut trapped in the middle cannot wiggle or swim to a handhold because any internal movement would not change their overall momentum relative to the station, keeping them in the same spot.