What is momentum, and how is it conserved in collisions?

Momentum is the product of mass and velocity (p = mv), measured in kg⋅m/s. In any collision, the total momentum before equals the total momentum after, as long as no external forces act on the system.

Step-by-Step Solution:
Calculate momentum using p = mv (mass × velocity)
For collisions: p₁(before) + p₂(before) = p₁(after) + p₂(after)
In elastic collisions, both momentum AND kinetic energy are conserved
In inelastic collisions, only momentum is conserved (energy is lost as heat/sound)
Verify your answer: Total momentum before = Total momentum after

Key Mistake to Avoid: Students often forget that momentum has direction (it's a vector), so signs (+ and -) are crucial when solving collision problems.


Required for: Combined Science and Physics

Quick Tip: Always draw a before/after diagram for collision questions, marking directions with arrows and clearly showing + and - velocities.