Definition
Definition of Impulse
Impulse accumulates force over time.
- \(\vec J=\int \vec F\,dt\)
- Units: N·s
- Vector direction
Momentum & Collisions · Physics
Impulse
Impulse measures how a force applied over a time interval changes momentum: \(\vec J=\int \vec F\,dt\).
This topic includes
Subtopics to master
Read force–time graphs, distinguish average vs instantaneous force, and interpret collisions.
Meaning
Impulse as Change in Momentum
Impulse equals momentum change: \(\vec J=\Delta \vec p\).
- Direction matters
- Large force, short time
- Small force, long time
Graphs
Force–Time Graphs
Impulse is the signed area under \(F(t)\).
- Area interpretation
- Piecewise graphs
- Sign of impulse
Forces
Average vs Instantaneous Force
Average force gives the same impulse over the interval: \(\vec J=\vec F_{\text{avg}}\Delta t\).
- Equivalent impulse
- When it’s valid
- Typical collision forces
Collisions
Impulse During Collisions
Collisions produce large forces over short times; impulse is still finite and measurable.
- Contact time
- Reducing peak force
- Safety design intuition
Practice
Practice & Exercises
Build skill reading \(F(t)\) and computing \(\Delta \vec p\).
- Area-under-curve drills
- Average force problems
- Impulse direction checks
- Collision impulse sets
- Quick conceptual quizzes