AQA Physics Unit 3 (P3) Mindmap

Mindmap to highlight key points in the Unit 3 Physics specification 

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  • Created by: Triciaaa
  • Created on: 15-04-13 14:37
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  • Physics Unit 3
    • Using Physics to Make Things Work
      • Moments
        • Turning effect of a force
        • m=fd
        • clockwise =anticlockwise
        • Levers = force magnifiers
        • Stability - line of action lies outside base >resultant moment > topple
      • Circular Motion
        • Centripetal force=tension, gravity, friction
        • Depends on mass, speed, radius
        • constant change in direction causing object to accelerate towards centre
      • Centre of Mass
        • point where its mass is thought to be concentrated
        • Freely suspended, rest at COM, directly below point of suspension
        • Symmetrical Asymmetrical shapes
        • Pendulum t=1/f
      • Hydraulics
        • incompressible, pressure transmitted equally in all directions
        • car braking systems,car jacks
        • P= F/cross sectional area
    • Keeping Things Moving
      • The Motor Effect
        • Magnetic field: regions where magnetic materials and wire carrying currents experience a force
        • Electromagnets magnify and demagnify
        • cranes - iron steel works
        • experiencing full force = wire must be 90º to MF
        • Flemings Left Hand
          • Thumb: Motion
          • First finger: field
          • Second finger: current
      • Transformers
        • Step up: more turns on 2nary
        • only works on AC
        • Step down: more turns on 1st
        • changing current produces changing MF, inducing the secondary coil
        • current of 1st inc/dec steadily, constant voltage induced in 2nd
    • Medical Applications of Physics
      • X-Rays
        • High frequency, short wavelength, ionising
        • Absorbed  by metal and bone, transmitted by healthy tissue
        • CT scans, treating cancer
      • Ultrasound
        • High frequency (<20,000Hz)
        • Non ionising, longitudinal waves
        • when the wave hits a boundary, some is transmitted and reflected
        • Ultrasound imaging = time taken for reflection  to reach detector
        • S=V x T
        • breaking down kidney stones, prenatal scanning
      • Lenses
        • Refractive index n = sin(i)/sin(r)
        • Convex (converges rays together)
          • Magnifies  (depends on distance away from object)
        • Concave (diverges rays away)
          • Always = virtual, upright, diminished
        • Virtual and real rays
      • Eye
        • Retina, lens, cornea, pupil, iris, ciliary muscle, suspensory ligaments
        • Far point = infinity
        • Near point = 25cm
        • Short sight - eyeball too long, cornea and lens too powerful
        • Long sight - eyeball too short, cornea and lens too weak
      • Other uses
        • Optical fibres - endoscopes
        • Lasers - cauterise
        • Refractive index = 1/sin(c)
        • Angle of incidence> critical angle = TIR
  • current of 1st inc/dec steadily, constant voltage induced in 2nd

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