Paper 2

• Scalar


  Variable that only has magnitude or size (a number)
• Vector


  Variable that has both magnitude and direction
• Finding the resultant vector

  1. Place vectors tip-to-tail

  2. For 2D, use Pythagoras to find magnitude

  3. Use trigonometry to find direction
• Component of a vector

  The part of a vector in a particular direction, found by multiplying the vector by cos or sin of the angle
• Types of forces


  • Contact forces (thrust, lift, friction, air resistance)
  • Non-contact forces (weight, electrostatic, magnetic)
• Weight


  Calculated as mass x gravitational field strength (9.81 N/kg)
• Work done


  Energy transferred by a force, equal to force x distance moved
• Hooke's Law


  Force = spring constant x extension
• Investigating Hooke's Law


  1. Fix ruler with 0 at bottom of spring

  2. Add 100g mass (usually just the hanger)

  3. Measure extension

  4. Increase mass up to 500g, measure extension each time

  5. Ensure eye is in line with spring and ruler to reduce parallax
• Motion graphs


  • Gradient of distance-time graph = speed
  • Gradient of velocity-time graph = acceleration
  • Area under velocity-time graph = distance
• Newton's Laws of Motion

  • 1st law: an object's motion remains constant if no external force
  • 2nd law: F = ma
  • 3rd law: to every action there is an equal and opposite reaction
• Investigating Newton's 2nd Law

  1. Use trolley on track with pulley and slotted masses

  2. Measure acceleration with light gates and data logger

  3. Vary mass of slotted masses, keep total mass constant

  4. Ensure trolley goes through 2nd gate before masses hit floor
• SUVAT equations


  Equations of motion: s = ut + 1/2 at^2, v^2 = u^2 + 2as, s = (u+v)t/2
• SUVAT equations are given, don't need to memorise them
• Using SUVAT equations


  1. Identify variables given

  2. Choose equation without unknown variable

  3. Rearrange to find unknown
• Projectile motion


  Horizontal motion uses speed = distance/time, vertical motion uses SUVAT
• Momentum


  Calculated as mass x velocity, conserved in collisions
• Force and momentum


  Force = change in momentum/time
• Stopping distance


  • Thinking distance + braking distance
  • Thinking distance depends on speed, braking distance depends on speed^2
• Moment (torque)


  Force x distance from pivot
• For equilibrium, sum of clockwise moments = sum of anticlockwise moments
• Pressure in liquids


  Pressure is the same throughout a liquid in a sealed system
• Transverse waves


  Oscillations perpendicular to direction of energy transfer
• Longitudinal waves


  Oscillations parallel to direction of energy transfer
• Examples of transverse waves: light, water waves, seismic S-waves
• Examples of longitudinal waves: sound, seismic P-waves
• Piston force


  Force is doubled when the piston area is doubled
• Waves


  Transfer energy without transferring matter
• Types of waves


  • Transverse
  • Longitudinal
• Transverse waves


  • Oscillations are perpendicular to the direction of energy transfer
  • Examples: light, electromagnetic waves, waves on water and string, seismic S waves
• Longitudinal waves


  • Oscillations are parallel to the direction of energy transfer
  • Examples: sound, seismic P waves
• Compression


  Regions in a longitudinal wave where particles are close together
• Rarefaction


  Regions in a longitudinal wave where particles are further apart
• Seismic P waves are faster than seismic S waves
• P waves can travel through the Earth's molten iron core, S waves cannot
• Displacement


  How far away particles are from their equilibrium or original position
• Amplitude


  The maximum displacement of the wave
• Wavelength


  The distance from one peak to the next or the length of one complete wave
• Time period


  The time taken for one complete wave to pass a point
• Frequency


  The number of complete waves that pass a point every second