Speed: measure of the distance an object travels per unit of time Units: m/s, km/h, mph Constant Speed: rate of change of position in which the same distance is traveled each second (with changing speed the rate of change is not the same for each second) Instantaneous speed: when speed is not constant it is the speed at a specific instant in time Average Speed: total distance traveled divided by the total time taken to travel that distance Calculate: Speed = Distance / time

The steeper the slope, the faster the speed Distance – Time Graphs Constant At rest Slowing down Speeding up The steeper the slope, the faster the speed

Calculating Average Speed from a graph (p154) Choose 1 point and record the coordinates (x1, y1) Choose a second point and record the coordinates (x2, y2) Find the difference in the times (x2- x1) Find the difference in the distances (y2- y1) Divide the difference in the distance by the difference in the time (S=d/t)

Velocity: Speed and DIRECTION Velocity changes when: Speed changes Direction changes Both speed and direction change Velocity is represented by arrows: length of the arrow shows the speed (faster speed = longer arrow) Arrows point in the direction of the movement