Core definition
Linear Momentum
Define momentum and learn what it means for particles and systems.
- Vector momentum
- Systems of particles
- Reference frames
Momentum & Collisions · Physics
Understand interactions through momentum.
Impulse, conservation, center of mass, collisions, explosions, and rocket motion — all as guided nano-lessons.
Momentum & Collisions topics
Core topics in this track
Work through in order, or jump to what you need right now.
Short interactions
Impulse
Impulse connects force over time to momentum change.
- Force–time graphs
- Average vs instantaneous
- Collisions
Key theorem
Impulse–Momentum Theorem
Turn Newton’s second law into a collision-ready tool.
- Derivation
- Short-time interactions
- Applications
Big idea
Conservation of Linear Momentum
Know when momentum is conserved and how to apply it in 1D and 2D.
- Isolated systems
- Internal vs external forces
- Vector conservation
Systems thinking
Isolated Systems & External Forces
Choose boundaries correctly to decide whether momentum conservation applies.
- System boundaries
- External impulses
- When conservation fails
Geometry
Center of Mass
Find the “average position” of mass for particles and continuous bodies.
- Discrete vs continuous
- Symmetry
- COM intuition
Motion
Motion of the Center of Mass
Link net external force to COM acceleration; use the COM frame.
- \u03A3F_ext and COM
- Explosions
- Collision analysis
Collision type
Elastic Collisions
Conserve both momentum and kinetic energy.
- 1D and 2D
- Energy + momentum
- Typical setups
Collision type
Inelastic Collisions
Momentum conserved, kinetic energy decreases.
- Energy loss
- Compare with elastic
- Real-world
Special case
Perfectly Inelastic Collisions
Objects stick together; maximum kinetic energy loss (for given momenta).
- Combined mass
- Shared velocity
- Dissipation
Solving mode
One-Dimensional Collisions
Head-on collisions with conservation laws and intro relative-velocity method.
- Head-on setups
- Conservation equations
- Relative speed idea
Vectors
Two-Dimensional Collisions
Use vector momentum conservation for oblique and scattering problems.
- Components
- Oblique collisions
- Scattering
Applications
Explosions & Recoil
Treat explosions as time-reversed collisions; use COM analysis.
- Recoil
- Conservation
- COM viewpoint
Advanced intro
Variable Mass Systems (Rocket Motion)
Momentum flow leads to the rocket equation (intro level).
- Variable mass idea
- Momentum flow
- Limits & assumptions