2. 2 Everything Science www.everythingscience.co.za Revision
Newton's laws Newtons 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. Newtons Third Law: If body
A exerts a force on body B then body B will exert an equal but
opposite force on body A. 3. 3 Everything Science
www.everythingscience.co.za 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=mv Fnet= p t 4. 4
Everything Science www.everythingscience.co.za 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 doesnt
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
5. 5 Everything Science www.everythingscience.co.za 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. 6. 6 Everything Science
www.everythingscience.co.za 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 t Impulse=p 7. 7
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