Graphing Displacement and Velocity

Types of Graphs In Physics 20, you are responsible for being able to make inferences based on graphical data. The two types of graphs which you will see most commonly are: Position vs. Time graph Velocity vs. Time graph

Position-Time Graph This graph depicts an objects position over time.

Position-Time Graph Different position-time graphs tell us different things. 1. Horizontal line: object is at rest. (ie. position does not change over time) 2. Linear: constant speed (velocity) 3. Curved: changing speed (velocity) = acceleration

Position-Time Graph The slope of a position-time graph is equal to the objects velocity. Always use the largest possible values for rise and run to get a more accurate slope value.

Position-Time Graph Instantaneous Velocity

Velocity-Time Graph Different velocity-time graphs can tell us different things. 1. Horizontal line: object is moving with constant speed (may be 0) (ie. look at y-intercept to determine speed/velocity) 2. Linear: changing speed (velocity), constant acceleration 3. Curved: changing acceleration (not in physics 20).  

Velocity-Time Graph The slope of a velocity-time graph is equal to the objects acceleration.

Velocity-Time Graph The “area under the curve” of the velocity-time graph is the objects displacement.

One more example….

To Summarize…. d vs. t graph v vs. t graph The position of the object The time Horizontal line - not moving and the y-intercept is the position Slope = speed or velocity The velocity of the object Horizontal line – constant velocity and the y-intercept is the velocity Slope = acceleration Area under the curve = distance/displacement

Homework pg. 3 #6 – 9 pg. 8 #2