Unit 2 - Chapter 6

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  • Created by: AnushaK
  • Created on: 13-02-14 17:51
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  • Ch 6
    • Scalars and vectors
      • Scalar - magnitude, no direction e.g. distance, time etc.
      • Vectors -  direction + magnitude e.g. displacement, velocity etc.
        • - line of length proportional to magnitude - arrow to show direction
        • In a straight line - add or subtract depending on direction
        • Perpendicular vectors - use SOHCAHTOA to find RESULTANT
          • AQA EXAMINER's TIP - use a large scale to reduce inaccuracy in measurement- use a sketch for calculations to ensure the right direction of the vectors
        • Cross Winds act at 90^ to direction of movement
          • Cross Currents act at 90^ to boating/ sailing
            • AQA EX TIP - vectors cannot be mixed up, so displacement and forces should not on velocity diagrams
              • Cross Winds act at 90^ to direction of movement
                • Cross Currents act at 90^ to boating/ sailing
                  • AQA EX TIP - vectors cannot be mixed up, so displacement and forces should not on velocity diagrams
        • Head winds and Tail winds
          • Wind velocity will add to or subtract from athlete's velocity
        • Air speed and ground speed - V_ground = V_air+V_wind
      • Resolving Velocities - splitting a vector into x and y component
      • Free-Body Diagrams - shows forces acting on only one object
        • Rules : 1. only draw one body 2.do not mark forces +resultant   3. Label clearly, full name or symbols if defined       4. only the tension as pull on the diagram should be marked
        • Forces on Free Body Diagram - Weight, Tension, Normal Reaction, Friction or drag, lift=object moves upward with aerodynamic forces, Upthrust = displacing gas or liquid, thrust.
    • Lift - shape of aircraft's wing, top surface curved, air flow over top faster, so less pressure above wing = net upward force
      • Wind velocity will add to or subtract from athlete's velocity
      • Thrust - driving force by pull of propellor or push of jet engine. Jet engine forces exhaust backwards = push aircraft forward
        • Drag - resistive force of air = slow aircraft down. Thrust = drag for aircraft flying at constant speed
    • Weight = Mass x gravity
      • Lift - shape of aircraft's wing, top surface curved, air flow over top faster, so less pressure above wing = net upward force
        • Thrust - driving force by pull of propellor or push of jet engine. Jet engine forces exhaust backwards = push aircraft forward
          • Drag - resistive force of air = slow aircraft down. Thrust = drag for aircraft flying at constant speed
    • Climbing + accelerating = lift > weight and thrust > drag. Resultant forces causes moving up and forward
      • Forces can be resolved like velocities - Tcos@ overcomes horizontal friction and Tsin@ overcomes weight of object to make it move vertically
        • Resolving Velocities - splitting a vector into x and y component

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