Module 1—Motion

Reflect and Connect

 

Graphs can be used to tell the story of motion, including the motion of an athlete. Consider the following scenario.

 

TR 12. Marly is sprint cycling and gets off to a good start, pedalling at a rate of 12.0 m/s for 10.0 s. She tires and slows down to 9.80 m/s for the next 16.0 s. When she gets close to the finish line, she begins pedalling at 11.5 m/s for the next 2.0 s. Sketch her position-time graph and velocity-time graph.

 

 

TR 13. Marly’s competitor, Michelle, starts the race at the same position and same time as Marly. However, she has a different strategy. Michelle pedals at a rate of 8.0 m/s for 8.0 s. She then speeds up to 15.0 m/s for the next 14.0 s. When she gets close to the finish line, she is tired and can only pedal at 10.0 m/s for the last 2.6 s. Sketch her position-time graph over top of Marly’s position-time graph.

 

TR 14. Come to the discussion area ready to share and discuss your graphs. Also, be prepared to discuss how you would determine where and when the two cyclists would meet and which strategy worked best if the race was only 250 m long.

 

Self-Check

 

SC 12. Go to page 65 of your textbook and complete question 3 of “Chapter 1 Review.” Note the units used in question 3(b), and make sure they are converted similar to “Example 1.2(b)” on page 15 of your textbook.

 

SC 13. Go to page 65 of your textbook and complete question 4 of the “Chapter 1 Review.”  Note carefully the units, and make sure they are converted similar to “Example 1.2(b)” on page 15 of your textbook.

 

SC 14. Go to page 65 of your textbook and complete question 6 of “Chapter 1 Review.”

 

SC 15. Go to page 66 of your textbook and complete question 15 of “Chapter 1 Review.”

 

Check your work.

 

Discuss

 

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Traffic-light synchronization is used in city planning as a way to alleviate traffic congestion and increase flow during peak travelling times. When four lights are synchronized, for example, a driver starting at traffic light 1 and travelling at the posted speed limit should arrive at each intersection as the light is turning green. Each light should be green for the amount of time it takes a driver to pass through all four intersections at the posted speed limit.

Prepare to discuss how to use a graphical method to determine the timing sequence of four traffic lights. You can use the lights shown below as a starting point for the discussion. Each intersection is separated by 200 m, and the speed limit is 60 km/h.

 

 

Reflect on the Big Picture

 

In this lesson you saw how graphs can assist you as you describe how objects are moving. The phrase “a picture is worth a thousand words” might well be used to summarize what you experienced. Did you find it helpful to see graphs used to explain motion in problems? Did you find that this lesson was much more densely packed with ideas than the first two?

 

To help you reflect on your learning experience in this lesson, complete at least one of these three activities:

Store your completed reflection in your Physics 20 course folder.

 

Module 1: Lesson 3 Assignment

 

Remember to submit the Module 1: Lesson 3 Assignment to your teacher.

 

Add to the KWL chart you worked on in Lesson 1 and 2. Continue to store your chart in your Physics 20 course folder.