Physics AS Mechanics

Created by: branerz_96
Created on: 04-01-13 14:06

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Physics AS Mechanics
- Motion
  - Motion graphs
    - average speed=distance/time
      - Displacement in a specific direction
        Gradient of displacement/time graph
    - Velocity/time graph
      - Gradient= acceleration
      - Area= displacement
  - Vectors
    - Represented by arrows
      - Trig to work out resultant force
      - If only have resultant force find compnents
  - Scalars
    - Vector Quatitys
      - Magnitude and direction
        Displacement
        
        Acceleration
        
        Force
        
        Velocity
        
        Momentum
    - Scalar Quatitys
      - Magnitude only
        Tempurature
        
        Density
        
        Distance
        
        Pressure
        
        Speed
- Work and Energy
  - Efficiency
    - efficiency=useful energy/total input energy
      - x 100 to make it percentage efficiency
    - Sankey diagrams
      - shows out put of an appliance. Useful and not useful
  - Conservation of energy
    - Energy cannot be created or destroyed
      - Only transformed
    - Sankey diagrams
      - shows out put of an appliance. Useful and not useful
  - Forms of energy
    - Chemical,Electrical, Gravitational potential, Nuclear, Sound, Knetic
      - Only transformed
      - Gravitational potential energy
        The energy a body has by virtue of its position in a gravitational field
        
        Ep=mgh
      - Knetic energy
        The energy a body has by virtue of its motion
        
        Ek=1/2 mv^2
  - Power
    - Watt(w)
      - 1 watt is the power when i joule is done in 1 second
        1W=1Js^-1
    - Power=work done/time taken
      - Power= transferred / time
        Watt(w)
        1 watt is the power when i joule is done in 1 second
        1W=1Js^-1
      - W=fx in direction of the force
  - Materials
    - Elastic
      - material stretches and follows hookes
        A material follows hookes law when the extention producedis proportional to the force providing it
        only when the elastic limit has not been exceeded
        When elastic limit has been reached object is permanently deformed
    - Young Moduls= stress/ strain
      - Stress=force/ cross sectional area
      - Strain= Extension/ Length
  - Work Done
    - W=fxcos0 is the force is at an angle to the direction of the force
      - W=fx in direction of the force
      - 1 Joule= 1 Newton metre, when a force of 1N moves an object over a distance of 1M
- Forces
  - Resultant forces
    - F=ma
      - Resultant force= massx acceleration
        The newton= force that causes 1KG to accelerate at 1ms^-1
      - Does not work for high speeds as mass increases
    - Balanced forces
      - Terminal velocity
        Drag= weight and acting forces
        Opposes motion
    - Weight=mg
  - Centre of gravity
    - Where all the WEIGHT is considered to act as 1 force
    - Find COG hang from 1 point, draw along plumb line, do with 2 more different points
  - Turning forces
    - Couple
      - 2 equal and opposite forces acting the opposite direction producing rotation
    - Torque describes the turning effect of the couple
      - Torque= force x perpendicular distance
  - Pressure
    - Pressure= force/ area
      - 1Pa= 1N spread evenly over 1m^2
        Force per unit area
  - Density
    - Mass per unit volume
      - Kgm^-3
      - Density= mass/ volume
    - Makes things float or sink
  - Car Safety
    - Crumple zones increase time of deceleration
      - seat belts and airs bags do the same
    - Thinking distance= speedx thinking time
      - Breaking distance UVAST
        Stopping distance= Breaking + Thinking

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Physics AS Mechanics

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