Momentum & Collisions · Physics

Impulse–Momentum Theorem

A compact statement: \(\displaystyle \int_{t_i}^{t_f}\vec F\,dt = \Delta \vec p\).

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Subtopics to master

Use the theorem to solve short-time force interactions without tracking every detail of motion.

Statement
Mathematical Statement
Impulse equals change in momentum.
  • \(\vec J=\Delta \vec p\)
  • Vector form
  • Component form
Derivation
From Newton’s Second Law
Start with \(\sum\vec F=d\vec p/dt\) and integrate over time.
  • Integration step
  • Constant vs variable force
  • Interpretation
Applications
Applications to Motion Problems
Solve for final speed/velocity, impulse, or average force.
  • Stopping problems
  • Push/launch problems
  • Direction changes
Timing
Short-Time Interactions
Collisions and impacts have tiny \(\Delta t\) but large impulse.
  • Why average force helps
  • Peak vs average
  • Area under \(F(t)\)
Practice
Practice & Exercises
Work impulse–momentum problems in 1D and 2D components.
  • Impulse from graphs
  • \(\Delta \vec p\) vector drills
  • Average force sets
  • Impact time reasoning
  • Quick concept checks