2. UNIT 3: Motion Chapter 5: Investigating Motion Chapter 6: Applied Motion

3. Chapter 5: Investigating Motion UNIT 3 Chapter 5: Investigating Motion TO PREVIOUS SLIDE Finding a store in a shopping mall and driving to a friend’s house are tasks that you might do without any thought. You might not think about motion when you do tasks like these, but these tasks involve motion and the description of motion. List some words that describe motion.

4. 5.1 Describing Motion UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE Telling someone how to get from one place to another, such as from their home to the movie theatre, is an example of describing motion. How would you describe the location of the woman holding the purse on the left side of the photograph relative to the man in the bowtie behind the counter?

5. Position UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE When you describe the position of an object, you must include a distance, a direction, and a reference point. Distance is a unit of length, and the SI base unit for distance is the metre. Compass points, or a “+” and “−” if you are using a number line, are used to describe direction. Number lines and coordinate systems are often used to specify position. What are two ways that you could describe the position of the skater on the right? Continued…

6. Position UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE Motion is the process of changing position. Two ways of describing motion are distance and displacement. Displacement is the straight-line distance, or the difference, between the initial position and the final position of an object. What distance did the player run in A, B, and C, and what is the displacement for each?

7. Scalar Quantities and Vector Quantities UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE A scalar is a quantity that has only magnitude (size) and is represented by a number and units. Scalars are distance, time, and temperature. A vector is a quantity that has both magnitude (size) and direction. Displacement and position are both vectors. Arrows are often used to represent vectors. The length of the arrow represents the size of motion. The arrow point represents the direction of motion. What is the runner’s displacement in the figure below?

8. Calculating Displacement UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE Displacement—the change in position—is represented by the equation below:

9. Choosing a Reference Point UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE An object’s position may change relative to one reference point, but it may not be moving relative to another reference point. When describing motion, it is important to include the reference point so your description will be clear. Describe a reference point that could be used to indicate that the man in the boat is NOT moving, and describe another reference point that could be used to show that the man IS moving.

10. Determining the Time Interval UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE The time interval is the difference between when an event begins and when that event ends. The SI unit for time is the second, s, and the symbol for time is t. The equation for finding the time interval is  t = t f – t i Use the equation above to find the time interval of your science class.

11. Uniform Motion UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE Uniform motion is motion in which the object’s displacement is equal for each time interval. Uniform motion is rare because frictional forces usually act on the object. Why does the motion diagram (B) show the uniform motion of the billiard balls more clearly than the photograph (A)?

12. Which graph represents an object that has uniform motion? Graphing Uniform Motion UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE Position-time graphs show the position of an object over time. When the motion of an object is a straight line on a position-time graph, the object has uniform motion.

13. Analyzing a Position-Time Graph UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE A positive slope on a position-time graph indicates that the object is moving in the positive direction. A negative slope on a position-time graph indicates that the object is moving in the negative direction. A zero slope on a position-time graph indicates that the object is not moving over time. Is the motion of the object positive or negative in this position-time graph? Is the motion uniform? How do you know?

14. Section 5.1 Review UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE When you describe the position of an object, you must include a distance, direction, and reference point. Units of length, such as metres and kilometres, are used to measure distance. Compass points and coordinate systems are often used to describe positions. Two ways of describing motion—a process of changing position—are distance and displacement. A scalar is a quantity that has only magnitude, such as distance, time, and temperature. Continued…

15. Section 5.1 Review UNIT 3 Chapter 5: Investigating Motion Section 5.1 TO PREVIOUS SLIDE A vector is a quantity that has both magnitude and direction, such as displacement and position. Vectors are used to represent motion, and they are added to find resultant vectors. Position-time graphs indicate if an object is moving in the positive direction, in the negative direction, or not moving at all.

16. 5.2 Distance, Time, and Speed UNIT 3 Chapter 5: Investigating Motion Section 5.2 TO PREVIOUS SLIDE Speed, v, is the distance an object moves in a certain length of time. Speed can be constant or changing. Constant speed is when an object travels the same distance for each time interval. Changing speed is when an object travels a different distance for each time interval. If there were no labels on the figure, how could you tell which car had constant speed and which car had changing speed? Continued…

17. Distance, Time, and Speed UNIT 3 Chapter 5: Investigating Motion Section 5.2 TO PREVIOUS SLIDE The slope of the line between any two points on a distance-time graph is the average speed the object is moving during that time interval. The average speed of an object is the distance travelled divided by the time it takes to travel that distance. The equation to calculate average speed is Continued…

18. Distance, Time, and Speed UNIT 3 Chapter 5: Investigating Motion Section 5.2 TO PREVIOUS SLIDE The slope of the line on a distance-time graph can be calculated using the following formula: Choose two points on the graph and determine the slope of the line, which is the average speed of the object. Continued…

19. Distance, Time, and Speed UNIT 3 Chapter 5: Investigating Motion Section 5.2 TO PREVIOUS SLIDE Instantaneous speed is speed at a specific instant of time. The speedometer in a car displays instantaneous speed. What is the instantaneous speed shown on this car speedometer?

20. Section 5.2 Review UNIT 3 Chapter 5: Investigating Motion Section 5.2 TO PREVIOUS SLIDE Speed is the distance an object moves in a certain length of time. Speed is a scalar quantity. There are many kinds of speed, including constant speed, changing speed, average speed, and instantaneous speed. The slope of the line between any two points on a distance-time graph is the average speed the object is moving during that time interval.

21. 5.3 Position, Displacement, and Velocity UNIT 3 Chapter 5: Investigating Motion Section 5.3 TO PREVIOUS SLIDE Velocity is a vector quantity that describes an object’s displacement during a specific time interval or an object’s rate of change of position. An object can have constant velocity or changing velocity. How do speed and velocity differ? Continued…

22. Position, Displacement, and Velocity UNIT 3 Chapter 5: Investigating Motion Section 5.3 TO PREVIOUS SLIDE The slope between any two points on a position-time graph gives the magnitude of the object’s average velocity during that time interval. Average velocity, v ave, is the displacement of an object divided by the time interval it takes to travel the displacement. Instantaneous velocity is the velocity (both magnitude and direction) at a specific instant of time. Calculate average velocity using the following equation: Continued…

23. Position, Displacement, and Velocity UNIT 3 Chapter 5: Investigating Motion Section 5.3 TO PREVIOUS SLIDE What does the bear appear to be doing after 13.5 h?

24. Section 5.3 Review UNIT 3 Chapter 5: Investigating Motion Section 5.3 TO PREVIOUS SLIDE Velocity is a vector quantity that describes an object’s displacement during a specific time interval or an object’s rate of change of position. There are many kinds of velocity, including constant velocity, changing velocity, average velocity, and instantaneous velocity. The slope between any two points on a position-time graph gives the magnitude of the object’s average velocity during that time interval.