physics motion

• Speed


  The distance moved by an object each second, measured in meters per second (m/s)
• Velocity


  A similar quantity to speed, but includes a direction (the direction of travel) as well as its value (its magnitude)
• Average speed


  Total distance / Total time
• Distance-time graph


  1. A horizontal line means stationary

  2. A straight line means constant speed

  3. If the line is going down, the object is moving backwards at constant speed

  4. If the gradient increases the object is speeding up (accelerating)

  5. If the gradient decreases the object is slowing down (decelerating)
• Acceleration


  The rate of change of speed (velocity): how much the speed (velocity) of an object changes by every second
• Velocity-time graph


  1. Distance travelled = area under the curve

  2. Area of trapezium = 1⁄2 ( b + a ) x h or

  3. Area of triangle 1 (distance when accelerating) + area of rectangle R (distance at constant speed)+ area of triangle 2 (area when decelerating)

  4. If the line is horizontal, the velocity is constant (no acceleration slope=zero)

  5. If the line slopes upwards, then the object is accelerating (speeding up slope positive)

  6. If the line goes down, then the object is decelerating (slowing down slope negative)
• Comparing the 4 patterns of motion

  • In distance-time graph (slope=speed)
  • In Speed-time graph (slope=acceleration)
• Calculating Distance travelled


  1. If the area beneath the graph forms a triangle (the object is accelerating or decelerating) then the area can be determined using the formula: area = 1⁄2 x base x height

  2. If the area beneath the graph is a rectangle (constant velocity) then the area can be determined using the formula: area = base x height

  3. Distance travelled = area under the curve

  4. Area of trapezium = 1⁄2 ( b + a ) x h or

  5. Area of triangle 1 (distance when accelerating) + area of rectangle R (distance at constant speed)+ area of triangle 2 (area when decelerating)
• In the absence of air resistance, all objects fall with the same acceleration, regardless of their mass
• This acceleration is equal to the gravitational field strength and is approximately 9.8 m/s2 near the Earth's surface
• So long as air resistance remains insignificant, the speed of a falling object will increase at a steady rate, getting closer to ground
• Acceleration is constant equals 9.8 m/s2
• In absence of air resistance in (vacuum) all objects, regardless of their mass or volume will fall with the same pattern, reaching the ground at the same time if they fall from the same height together