1. - Review the concepts of speed and average speed - Investigate acceleration and non- uniform motion - Learn how different types of motion relate to velocity and acceleration TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY

2. 8. Ann and Beth went to the airport. Ann stopped for lunch, and Beth didn't. Here is a graph of their trips. How did their average speeds compare? Was Ann’s average speed greater than, the same as, or less than Beth’s? 9. As you can tell from the graph, Ann drove the first 40 miles at 60 mph, and then stopped for lunch, which took 20 minutes. But now she was going to be late, so she drove the rest of the way (35 miles) at 70 mph. What was her average speed for the trip? Because both drivers traveled the same distance in the same total time, their average speeds were the same. Average speed = total distance / total time = 75 miles / 90 minutes = 0.833 miles/minute = 50 miles/hour

3. Average speed must account for the stopped time, and for the different AMOUNTS of time spent at each speed. On a distance vs. time plot, a steeper slope describes a higher speed. Ann goes the same speed the whole time - how does her average speed compare to her speed at any moment in the trip? Ann’s average speed equals her speed at any instant on the trip, because her speed was CONSTANT. Except for when she stopped, how does Beth’s speed during the trip compare to her average speed? Beth’s average speed was lower than her actual speed while she was moving, because her stop time lowered the average.

4. time (minutes) distance (miles) 10 20 30 40 1020 30 4050 60 Straight line means constant speed What is the average speed here? What is the speed at 10 minutes? at 30 minutes? at 45 minutes? Average speed = speed only if the speed is constant. In your plots for the rolling balls, was the speed constant? 40 miles/hour

5. time (minutes) distance (miles) 10 20 30 40 1020 30 4050 60 What if you have a totally non-constant speed? Can you still find average speed? Average speed over an interval depends only on the start position and time, and the end position and time. Average speed is the slope of the line connecting the start and end points on a distance vs. time plot. YES - it is 40 miles/hour

6. - How to determine average speed from distance and time data - How to plot and interpret distance vs. time data WHAT YOU ARE EXPECTED TO KNOW:

7. - Review the concepts of speed and average speed ✓ - Investigate acceleration and non- uniform motion - Learn how different types of motion relate to velocity and acceleration TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY