Understanding Momentum

Momentum is a fundamental concept in physics that describes the quantity of motion an object has. It is the product of an object's mass and velocity, expressed as p = mv.

Key Formulas

• Momentum: p = mv (mass × velocity)
• Impulse: J = FΔt = Δp (force × time = change in momentum)
• Conservation: Total momentum before = Total momentum after

Types of Collisions

Elastic Collisions

In elastic collisions, both momentum AND kinetic energy are conserved. The objects bounce off each other without any energy loss. Examples include billiard ball collisions and atomic particle interactions.

Inelastic Collisions

In inelastic collisions, momentum is conserved but kinetic energy is not. Some energy is converted to heat, sound, or deformation. In a perfectly inelastic collision, the objects stick together after impact.

Impulse-Momentum Theorem

The impulse-momentum theorem states that the impulse applied to an object equals the change in its momentum: J = Δp. This explains why airbags work - by increasing the collision time, they reduce the force on passengers.

Real-World Applications

• Vehicle safety design (crumple zones, airbags)
• Sports (baseball bats, golf clubs)
• Rocket propulsion
• Particle physics experiments
• Ballistic calculations

SI Units

Momentum is measured in kilogram-meters per second (kg·m/s), which is equivalent to Newton-seconds (N·s). Both units represent the same physical quantity.