1. Plotting graphs Drawing best fit lines (or curves) Calculating slope = calculating velocity Describing Motion: Position vs Time Graphs

2. Plotting Graphs: Set up axes: Horizontal: time: choose an interval to fit the entire data set, set up the scale, label the scale, label the axis: “time, sec” Vertical: position: choose an interval to fit the entire data set, set up the scale, label the scale, label the axis: “position, m” Find each data pair and sketch a point on your graph Data Set Time, s#1, m 2.325 5.1710 7.6615 10.5820 14.1325 16.330 17.5535 21.0140 23.3245 26.3250 29.0655 31.7260 33.9765 39.6575 45.0285 47.690

3. Interpreting Position-Time Graph Velocity = change in position per unit time From the Graph: 1. Which object moves faster? #1 is faster 2. How can you tell? Moves farther in the same time Greater displacement per unit time The line is steeper The line has a greater slope 3. Is the motion steady? Equal displacements per unit time Straight line Constant slope Constant velocity

4. Interpreting Position-Time Graph Sketch the best-fit lines: Calculate Velocity: #2: (70m)/(10s) = 7 m/s #1: (20 m)/(10 s) = 2 m/s VELOCITY = SLOPE Velocity = change in position per unit time

5. Interpreting Position-Time Graph Velocity = slope From the Graph: 1. Is the motion steady? NO 2. How can you tell? Unequal displacements per unit time Curved line Changing (increasing) slope Changing velocity 3. Which object speeds up? #4 4. How can you tell? How can you tell? Position changes more and more rapidly The curve is getting steeper The slope is increasing Increasing velocity

6. Velocity from Position-Time Graph 1. Find the change in position for 5 intervals of 5 seconds: 2. Calculate Velocity: 0 – 5 sec: (37m)/(5s) = 7.4 m/s 5 – 10 sec: (27m)/(5 s) = 2.4 m/s 10 – 15 sec: (17m)/(5s) = 3.4 m/s 15 – 20 sec: (7m)/(5s) = 1.4 m/s Velocity = change in position per unit time

7. *Plotting Velocity-Time graph Calculated Velocity: Graph: Time, secVelocity, m/s 57.4 105.4 153.3 201.5