Summary presentation for grade 12 physics momentum and impulse

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2. Momentum and Impulse
Physics
Grade 12

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Revision – Newton's laws
Newton’s Second Law:
The resultant force acting on a body will cause the body to accelerate in the direction
of the resultant force The acceleration of the body is directly proportional to the
magnitude of the resultant force and inversely proportional to the mass of the object.
Newton’s Third Law:
If body A exerts a force on body B then body B will exert an equal but opposite force
on body A.

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Momentum
The linear momentum of a particle (object) is a vector quantity equal to the product of the
mass of the particle (object) and its velocity.
Momentum and Newton's second law
The net or resultant force acting on an object is equal to the rate of change of momentum.
⃗p=m⃗v
⃗Fnet=
Δ ⃗p
Δt

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Conservation of momentum
A system is a physical configuration of particles and or objects that we study.
An isolated system is a physical configuration of particles and or objects that we study that
doesn’t exchange any matter with its surroundings and is not subject to any force whose
source is external to the system.
Principle of conservation of linear momentum: ‘The total linear momentum of an isolated
system is constant’ or ‘In an isolated system the total momentum before a collision (or
explosion) is equal to the total momentum after the collision (or explosion)’.
⃗pT= ⃗p1+ ⃗p2+ ⃗p3+ … + ⃗pn

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Collisions
Elastic collision: both total momentum and total kinetic energy are conserved.
Inelastic collision: only total momentum is conserved, total kinetic energy is not conserved.

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Impulse
Impulse is the product of the net force and the time interval for which the force acts.
Impulse-momentum theorem
Impulse-momentum theorem: the impulse is equal to the change in momentum.
Impulse= ⃗Fnet⋅Δ t
Impulse=Δ⃗p

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