AQA combined physics paper 2

• Force is any push or pull

  • Forces can be contact (physically touching objects) or non-contact (like magnetism, electrostatic forces, and gravity)
  • Contact forces include normal contact force, friction, air resistance, and tension
  • Forces can be represented with vectors (arrows showing direction and magnitude)
• Resultant force:

  • If two forces act on an object, there is a resultant force
  • Resultant force is found by adding vectors
  • If forces are going in opposite directions, one must be negative
  • Resultant force can be positive or negative based on the chosen direction
• Balanced forces:

  • If forces are balanced (add up to zero), the object will not accelerate
  • Balanced forces do not necessarily mean the object is not moving, just that it stays at a constant velocity (could be zero m/s)
  • Newton's first law of motion states that an object's motion is constant when there is no resultant force
• Scalars vs. Vectors:

  • Scalars have magnitude but no direction (e.g., distance)
  • Vectors have magnitude and direction (e.g., displacement, velocity)
  • Weight is a force due to gravity, calculated by mass x gravitational field strength (9.8 N/kg on Earth)
• Energy and Work Done:

  • Work done = force x distance
  • Work done is energy transferred by a force
  • Energy used to lift an object is calculated using mass x gravity x height
  • Energy stored in a spring = 0.5 x spring constant x extension
• Speed, Velocity, and Acceleration:

  • Speed and velocity are measured in m/s
  • Velocity includes direction (positive or negative)
  • Acceleration is the rate of change of speed, unit is m/s^2
  • Acceleration can be negative (deceleration)
• Doubling your speed quadruples your braking distance
• Kinetic energy is equal to half MB squared
• Factors affecting thinking distance: distractions, alcohol, drugs
• Factors affecting braking distance: condition of brakes, tires, road, weather
• Momentum is equal to mass times velocity
• Total momentum is always conserved in a collision
• Force is equal to change in momentum over time
• Waves transfer energy without transferring matter
• Longitudinal waves have oscillations parallel to the direction of energy transfer (e.g., sound waves)
• Transverse waves have oscillations perpendicular to the direction of energy transfer (e.g., waves on water surface)
• Amplitude is the peak of a wave, representing the maximum displacement from equilibrium
• Wavelength (λ) is the distance of one complete wave, measured in meters
• Time period (T) is the time for one complete wave to pass, measured in seconds
• Frequency is the number of waves passing a point every second, measured in hertz (Hz)
• Wave speed (V) equals frequency times wavelength (V = fλ)
• EM waves can travel through the vacuum of space
• EM waves are absorbed by electrons for various purposes like communication, heating, and imaging
• Refraction occurs when light changes speed and direction when moving from one medium to another
• Permanent magnet: a metal with molecules permanently aligned to produce a magnetic field
• Two ends of a magnet are named North and South Pole
• Induced magnet: a material whose particles align temporarily when placed in a magnetic field
• Current flowing through a wire produces a magnetic field with concentric circles around it
• Motor effect: wire in a magnetic field experiences a force, given by the equation f = BIL
• Fleming's left-hand rule determines the direction of the force on the wire
• Electric motors use the motor effect with a coil of wire experiencing opposite forces to turn
• Loudspeakers use varying current to cause a coil to vibrate and produce sound waves