Principles of Physics: Mechanics, Forces, and Circular Motion

physics mechanics 11 vector quanticies have a size and direccion e.g. weight, displacement forces scalar quantities have a size but no direction e.g. mass, speed, time FORCES - a push, pull or twist that makes objects change speed or direccion forces are measured in newcons(N) & represented by arrows on a diagram MOTION Newton's 1st Law: an object will remain at rest or in conscant motion unless acted upon by an external force Newton's 2nd Law the acceleration of an object is directly proporational to the net force acting on ie and inversely proportional co ICS mass. Newton's 3rd Law: every action has an equal and opposice reaccion COLLISIONS Elastic : momentum, kinecic energy & total energy are conserved. Partially Inelascic kinecic energy is reduced and objects move apart. Totally Inelastic kinecic energy is reduced and objects scick together. W/ MATERIALS Hooke's Law extension of a stretched material is directly proporcional to force, under the elastic limit. elastic issues and ductile make Seases youngs me medicos elaseic area= parential strain energy extension (m) Strain Brittle materials, such as glass and casciron obey Hooke's law until breaking point; duccile tensile strength Elastic or rubber, does not obeyHooke's Law at any point - energy islast whilse materials inicially obey Hooke's law, then pass the clascic limit prior to breaking at the ultimate rearranging chemical bonds. CIRCULAR MOTION s Linear speed is constant, although directional o velocity is not - ergo the acceleration is not constant by newcon's 2nd law, a force must be acting:- the centriperal force,