A2- Bubble map

A2- Bubble map

1. Mechanics

   • Scalars and vectors
     • Scalar quantities have magnitude e.g. distance
     • Vector quantities have magnitude and direction e.g. displacement
   • SUVAT
     • v= u + at
     • s= ut + 1/2at^2
     • v^2= u^2 + 2as
     • s= (u+v) / 2 x t
   • Projectiles
     • Two objects of different mass and same air resistance accelerate towards the ground at the same rate
     • A projectile fired horizontally moves at constant speed horizontally and accelerates downwards at a rate of 9.81ms^-2
   • Graphs
     • Gradient= velocity
     • Curved line for acceleration
     • Straight line for constant velocity
     • Area under the line= distance
     • Gradient= acceleration
     • Curved line for non-uniform acceleration
     • Straight line for constant acceleration
   • Mass + weight
     • Mass= amount of matter in an object (kg)
     • Weight= force experienced by a mass due to a gravitational field
     • Density= mass / volume
   • Forces
     • Forces at right angles use Pythagoras to find resultant
     • To resolve a force split it into horizontal and vertical components using trig
   • Newton's laws
     • 1st law is a body will remain at rest or continue to move at a constant velocity unless the forces acting on it are balanced
     • 2nd law is the acceleration of a body is proportional to the resultant force and takes place in the direction of the force e.g. W=mg
     • 3rd law is whilst body A exerts a force on body B, body B exerts an equal and opposite force on body A
   • Work and power
     • Work done= force x distance moved (in direction of force)
     • Power= work done / time
     • Power= force x velocity (x cos0 if force and motion are in different directions)
   • Conservation of energy
     • Energy cannot be created or destroyed only transferred from one form to another
     • As a ball is thrown up into the air the kinetic energy is transferred to gravitational potential and visa versa when it falls

2. Materials

   • Hooke's law
     • F= ke
     • Force is proportional to extension
   • Stress and strain
     • Stress= force / area
     • Strain= extension / length
     • Elastic strain energy= 1/2ke^2
   • Young's modulus
     • YM= stress / strain
     • YM= force x length / extension x area
   • Behaviour of solids
     • Brittle= won't deform plastically but will snap at a certain force
     • Ductile= can be drawn out without losing strength
     • Malleable= can change the shape but may lose the strength
     • Hard= resistant to cutting, indentation and abrasion
     • Stiff= resistant to bending and stretching
     • Tough= lots if energy needed to break
   • Flow
     • Laminar flow has parallel layers of streamlines
     • Turbulent flow has mixed layers with whirlpools
   • Viscosity
     • Viscous drag is the friction between flowing fluid elements
     • The higher the temperature the lower the viscosity
     • Viscous drag= 6 x pi x viscosity x radius x velocity

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