physics 2

• A scalar quantity is just a number
• Vector quantity


  A number and a direction
• Scalar quantities


  • Distance
• Finding resultant force


  Difference between forces
• Weight


  Mass times gravity
• Weight


  Measured in newtons
• Mass


  Measured in kilograms
• Gravity


  Measured in newtons per kilogram
• Weight changes depending on planet/gravity, mass does not change</b>
• Work


  Force times distance, measured in joules
• Hooke's Law


  1. Increasing force increases extension

  2. Limit of proportionality reached, no more stretching
• Force


  Spring constant times extension, measured in newtons
• Kinetic energy


  1/2 mass times velocity-squared, measured in joules
• Fluid


  Liquid or gas
• Pressure


  Force over area, measured in pascals
• Pressure


  Height times density times gravitational field strength, measured in pascals
• Distance equals speed times time
• Distance-time graphs


  • Increasing slope = moving, flat line = not moving
  • Gradient = speed
• Velocity-time graphs


  • Flat = steady speed, increasing = accelerating
  • Area under graph = distance
• Acceleration


  Change in velocity over time, measured in m/s^2
• Final velocity-squared minus initial velocity-squared

  Equals 2 times acceleration times distance
• Terminal velocity


  Reached when all forces are balanced
• Free-falling speed is 9.8 m/s
• Newton's cradle


  • Demonstrates inertia, conservation of energy, Newton's 3rd law
• Inertia


  Object at rest stays at rest, object in motion stays in motion, unless acted on by a force
• Force


  Mass times acceleration, measured in newtons
• Stopping distance


  • Thinking distance + braking distance
  • Affected by speed, tires, road conditions, car weight
• Car safety features include seat belts, airbags, crumple zones
• Momentum


  Mass times velocity, measured in kg m/s
• Law of conservation of momentum: momentum before = momentum after
• Transverse wave


  • Oscillates up and down, wavelength, amplitude, direction of movement and energy transfer
• Longitudinal wave


  • Areas of compression and rarefaction, wavelength, direction of movement and energy transfer
• Frequency


  Number of waves per second, measured in hertz
• Time period


  1 over frequency, measured in seconds
• Wave movement


  1. Moves from the middle to the top or from the middle to the bottom

  2. Direction of movement is up and down

  3. Direction of energy transfer is sideways
• Longitudinal wave


  Areas of compression and areas of refraction
• Wavelength


  Distance from one point to another point on the wave
• Frequency


  Number of waves per second
• Frequency


  Inversely related to wavelength
• Time period


  One over the frequency