# Linear Momentum

## Linear Momentum

• Linear momentum is a vector quantity used to describe the motion of an object. It’s defined as the product of an object’s mass and its velocity.
• Represented by the letter ‘p’, linear momentum can be calculated using the formula p = mv, where m is the mass of the object and v is its velocity.
• Since velocity is a vector quantity, momentum also has both magnitude and direction. Consequently, the momentum of an object can change either if its speed changes (magnitude) or if it changes direction.
• The total momentum of a closed system will always remain constant, as long as no external forces act on the system. This principle is known as the conservation of momentum.

## Conservation of Momentum

• According to the conservation of momentum, the total linear momentum before an event (such as a collision or explosion) is equal to the total linear momentum after the event. This applies if no external forces influence the system during the event.
• The principle is an outcome of Newton’s Third Law, which states that for every action, there is an equal and opposite reaction. As such, the changes in momentum for each object in a system will cancel each other out.

## Applications of Linear Momentum

• Understanding linear momentum and conservation of momentum principles can help in analysing various physical situations, such as the motion of rocket propulsion, the behaviour of objects during collisions and explosions or predicting the final state of a system when the initial conditions are known.
• It plays a substantial role in collision problems, including elastic collisions (where kinetic energy is conserved) and inelastic collisions (where kinetic energy is not conserved).
• Knowledge of momentum can provide an insight into why an object at rest is harder to move than one in motion and how the acceleration of objects can affect their momentum.
• This concept also allows researchers to estimate the mass or velocity of moving objects when other parameters are known, solving real-world problems.
• Momentum is also applicable in various fields of physics like quantum mechanics and special relativity, signifying the broad scope of this fundamental quantity.