AQA Physics Unit 3 (P3) Mindmap
Mindmap to highlight key points in the Unit 3 Physics specification
- 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
- Moments
- 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
- The Motor Effect
- 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
- X-Rays
- Using Physics to Make Things Work
- current of 1st inc/dec steadily, constant voltage induced in 2nd
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