Momentum and impulse - Momentum

Momentum and impulse



In this lesson, we will learn:

  • What is impulse?
  • Derivation of impulse from Newton's second law
  • Impulse equations, units
  • Problem solving with impulse and momentum
  • Problem solving with F vs t graph


  • Impulse is change in an object's momentum.
  • To change an object's momentum, an impulse must be given to that object. An example would be kicking a soccer ball (an impulse) to set it into motion (give it momentum).
  • An impulse is defined as a force that acts on an object for a period of time.
  • In a graph of force vs. time, the area under the graph is impulse.


p=mv\vec{p} = m \vec{v}

p:\vec{p}: momentum, in kilogram meters per second (kg∙m/s)

m:m: mass, in kilograms (kg)

v:\vec{v}: velocity, in meters per second (m/s)


J=FΔt=Δp=m(vfvi\vec{J} = \vec{F} \Delta t = \Delta \vec{p} = m( \vec{v}_f - \vec{v}_i)

J:\vec{J}: impulse, in newton seconds (N∙s)

F:\vec{F}: net force acting on an object, in newtons (N)

Δt:\Delta t: the length of time for which the force acts, in seconds (s)

Δp:\Delta \vec{p}:change in momentum of an object, in kilogram meters per second (kg∙m/s)

  • Intro Lesson
    Introduction to impulse and momentum:
  • 1.
    Impulse = F\bold{\vec{F}}Δt=Δp\bold{\Delta t = \Delta \vec{p}}
  • 2.
    Impulse = F\bold{\vec{F}}Δt=m(vfvi)\bold{\Delta t = m(\vec{v}_f - \vec{v}_i )}
  • 4.
    Impulse = area under Fvst\bold{F\;\mathrm{vs}\; t} graph, during the time interval Δt \bold{\Delta t}
  • 5.
    Momentum and Impulse in two dimensions
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Momentum and impulse

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