Measuring Motion  Speed  Velocity  Acceleration

Speed  The distance traveled by an object divided by the time taking to travel that distance

Speed  Equation: Average Speed = total distance total time total time  SI Units: *meters per second (m/s) *kilometers per hour (km/h) *feet per second (ft/s) *miles per hour (mi/h)

Speed  Example: Suppose a hot air balloon traveled 50 meters in 10 seconds. What is the balloon’s speed? Suppose a hot air balloon traveled 50 meters in 10 seconds. What is the balloon’s speed?  Remember – Speed is equal to total distance divided by total time.

Velocity  The rate of change of an object’s position over time  Velocity = displacement time  Change in position means you must indicate a direction.

Displacement  The change in the object’s position compared to the starting point.  The difference between an object’s starting position and ending position.  Sometimes confused with distance which is the total amount traveled

Graphing Velocity

Position-Time Graphs A change in an object’s position or displacement can be graphed over time using this Position-Time Graph. Distance (m) Time (s)

Constant Velocity When an object is moving at a constant velocity, it is moving the same distance for each time period. This is shown on the graph using a straight line.

 If the object is NOT MOVING it can still be graphed using the position-time graph.  The distance traveled or displacement does not change over time.

Acceleration  The rate at which velocity changes  An object accelerates if its speed, direction, or both change  An increase in velocity is called positive acceleration  A decrease in velocity is called negative acceleration

Acceleration  Equation: Average Acceleration = Average Acceleration = final velocity – starting velocity time it takes to change velocity final velocity – starting velocity time it takes to change velocity  SI Units: *Velocity is expressed in m/s and time is expressed in seconds (s) *Acceleration is expressed in m/s 2

Acceleration  Example: A plane passes over point A at a velocity of 240 m/s north. Forty seconds later, it passes over point B at a velocity of 260 m/s north. What is the plane’s average acceleration? A plane passes over point A at a velocity of 240 m/s north. Forty seconds later, it passes over point B at a velocity of 260 m/s north. What is the plane’s average acceleration?