Motion- an object is moving if its distance from another object is changing.
Reference Point- A place or a object used for comparison to determine if something is in motion (tree, sign or building)
International System of Units- Scientists all over the world use the same system of measurement so that they can communicate clearly. (1000 m - 1 KM)
Average Speed- the total distance traveled over the total time.
Instantaneous speed- the rate at which an object is moving at a given instant in time.
Velocity- speed in a given direction. (air traffic controllers)
Slope- the steepness of a line on a graph.
Acceleration- the rate at which velocity changes.

Key Concepts:
1 - Describing and Measuring Motion

  • an object is in motion if it changes position relative to a reference point.
  • Scientists use SI units to describe the distance an object moves.
2 - Speed and Velocity
  • If you know the distance an object travels in a certain amount of time, you can calculate the speed of an object.
  • Speed= distance/time
  • When you know both the speed and direction of an object's motion, you know the velocity of the object.
  • You can show the motion of an object on a line graph in which you plot distance versus time.
  • Slope= rise/run (rate of change) slope=speed
3 - Acceleration
  • In science acceleration refers to increasing speed, decreasing speed, or changing direction.
  • To determine the acceleration of an object moving in a straight line, you must calculate the change in speed per unit of time.
  • Acceleration=Final Speed-Initial Speed/time
  • You can use both a speed versus time graph and a distance versus time graph to analyze the motion of an accelerating object.