P2.1 - Motion

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iqra

Cards (26)

  • Light gates are used to measure the time taken. The timer starts and stops when an object interrupts its beam.
  • When using a stopwatch, the reaction time of the person can affect the accuracy of the and precision of measurements.
  • Ultrasound can be used to measure distances. The device measures the time taken for a pulse to travel to an object and back. It uses this value and the speed of the pulse to work out the distance.
  • In uniform motion, speed is constant:
    distance (m) = speed (m/s) * time (s)
  • In non-uniform motion, is when speed changes:
    average speed (m/s) = total distance (m) / total time (s)
  • The Sl unit of distance is metres, and the Sl unit of time is seconds.
  • There are 1609 metres per mile.
  • There are 3600 seconds per hour.
  • Quantities with a magnitude and direction are vectors.
  • Quantities with only a magnitude are scalar.
  • Vectors can be represented by arrows:
    • The length shows its magnitude.
    • The direction shows the direction.
  • You can decide what directions are positive or negative for vectors.
  • Velocity is a vector, speed is scalar.
  • Acceleration is the change in velocity per second.
  • Uniform acceleration means that the acceleration is constant.
  • Uniform acceleration (m/s2^2) = change in velocity (m/s) / time (s)
  • Acceleration (m/s2^2) = final velocity - initial velocity (m/s) / time (s)
  • Acceleration due to gravity is 9.81 m/s2^2.
  • For the acceleration due to gravity, every second the objects velocity increases by 10 m/s2^2.
  • The speed is equal to the gradient or slope of a distance-time graph:
    • A straight line means speed is constant.
    • A horizontal line means that the object is stationary.
    • The steeper the line, the higher the speed.
  • A displacement-time graph's gradient can be positive, zero, or negative.
  • The line a displacement-time graph represents velocity.
  • The distance is the area under a speed-time graph.
  • The displacement is the area under a velocity-time graph.
  • final - initial velocity = 2 * acceleration * distance
    • Note: distance can be replaced with displacement.
  • Kinetic energy = 0.5 x mass x speed2^2