This definitions covers Key Definitions within Momentum for GCSE Physics. Revise Momentum in Forces for GCSE Physics with 13 exam-style questions and 6 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 12 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
📖 Key Definitions
Momentum (p): The product of mass and velocity. p = mv. Unit: kg m/s. Momentum is a vector quantity — direction matters.
Conservation of momentum: In a closed system, the total momentum before an event equals the total momentum after. Total momentum does not change.
Closed system: A system with no net external forces acting on it, so total momentum is conserved.
Elastic collision: A collision where both momentum AND kinetic energy are conserved. Objects bounce apart.
Inelastic collision: A collision where momentum is conserved but kinetic energy is NOT (some converted to heat/sound). Objects may stick together.
Practice questions for Momentum
What is the equation for momentum?
Explain what is meant by saying momentum is a vector quantity.