How fast we move and in what direction are we going. Speed and Velocity How fast we move and in what direction are we going.

Speed Speed is a ratio of the distance an object moves to the amount of time it moves Speed = distance/time The SI unit for speed is meters/second (m/s) km/hour is also used

Average Speed It is the total distance traveled divided by the total amount of time it took Average speed = total distance/total time The formula is v=Δd/Δt Δ is the Greek letter delta and it means change

Calculating Average Speed While traveling on vacation, you measure the times and distances traveled. You traveled 35 kilometers in 0.4 hour, followed by 53 kilometers in 0.6 hour. What is your average speed? Use the formula v = total distance/total time Total distance (d) = 35 km + 53km = 88km Total Time (t) = 0.4h + 0.6h = 1.0h v = 88km/1hr = 88km/hr

Instantaneous Speed The rate an object is moving at any given moment in time is instantaneous the speedometer in a car shows instantaneous speed

Graphing Motion Distance and time can be graphed in a line graph slope = rise/run In a distance-time graph the slope of the line is the speed A constant speed will give a diagonal line When the line is horizontal the car is not moving (stopped)

Graphing Motion Constant High Speed Distance (meters) Time (seconds)

Varying Speed Distance (meters) Time (seconds)

Velocity Velocity is the speed and direction an object is moving, it is a vector A change in velocity is a change in speed, a change in direction or both When an object is moving at a constant speed and direction it has constant velocity