2 Observing motion by using a reference point Reference point – an object that appears to be stationary or mobile. An object used to compare another object in motion.Reference direction – Used to describe the direction of an object’s motion.Up, down, north, south, east and westMotion – an object’s change in position relative to a reference point.
3 Speed Depends on Distance and Time Speed – is the distance traveled by an object divided by time taken to travel that distanceThe SI unit for measuring speed is meters per second (m/s), or kilometers per hour km/h.
4 Determining Average Speed Most of the time objects do not travel at a constant speed. It is useful to calculate average speed.Average speed = total distancetotal time