1 / 7

- Review the concepts of speed and average speed

Explore speed & average speed, changing directions in motion, speed representations in graphs. Analyze Ann & Beth's trip & average speeds. Calculate average speed with stoppage. Understand average speed vs. instant speed & non-constant speeds. Learn to plot & interpret distance vs. time data.

joneslois
Download Presentation

- Review the concepts of speed and average speed

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY - Review the concepts of speed and average speed - Determine what is required to make a moving object change direction - Learn how to represent different types of motion with graphs

  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? Because both drivers traveled the same distance in the same total time, their average speeds were the same. 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? • Average speed = total distance / total time • = 75 miles / 90 minutes • = 0.833 miles/minute = 50 miles/hour Averaging the two numbers is not the correct way to do this!

  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. Average speed = speed only if the speed is constant. In your plots for the rolling balls, was the speed constant? 40 Straight line means constant speed 30 What is the average speed here? distance (miles) 20 40 miles/hour 10 What is the speed at 10 minutes? 40 miles/hour 40 50 30 60 10 20 at 30 minutes? time (minutes) 40 miles/hour at 45 minutes? 40 miles/hour

  5. 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 40 What if you have a totally non-constant speed? Can you still find average speed? 30 distance (miles) 20 10 40 50 30 60 10 20 time (minutes)

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

  7. TODAY’S OUTCOMES: FORCE, MOTION AND ENERGY - Review the concepts of speed and average speed✓ - Determine what is required to make a moving object change direction - Learn how to represent different types of motion with graphs

More Related