The law of conservation of linear momentum states that in a closed system, the total momentum remains constant and is not affected by external forces. This means that the total momentum before and after an event must be the same.
Linear momentum is defined as the product of an object's mass and velocity. It is a vector quantity, meaning it has both magnitude and direction. The SI unit for momentum is kg*m/s.
One example of conservation of linear momentum is when a cannon fires a cannonball. The momentum of the cannonball is equal to the momentum of the cannon in the opposite direction. Therefore, the total momentum before and after the firing is the same.
In an elastic collision, both momentum and kinetic energy are conserved. This means that after the collision, the objects involved will have the same total momentum and total kinetic energy as before. In an inelastic collision, only momentum is conserved, but kinetic energy is not. Some kinetic energy is lost as heat or sound, resulting in a decrease in total kinetic energy after the collision.
The law of conservation of linear momentum has many real-life applications, such as in sports, transportation, and rocket propulsion. For example, the recoil of a gun after firing is due to the conservation of linear momentum. In addition, the concept of momentum conservation is used in designing efficient and safe transportation systems, such as airbags in cars.