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Name: _______________________________ Grade: 10 B1 B2 Please circle your section Date: ___NOV 2017 Sayel Abu Alrob PHYSICS DEPARTMENT Grade 10 Physics Teaching Notes #3 Position-Time Graph Term 1 Representing Motion Position-Time Graph How Fast MAIN IDEA You can use position-time graphs to determine an object’s position at a certain time. Objectives Checklist: Practice the plotting of position-time graph Read and analyze the position time graph Compare the motion of two objects in position-time graph Calculate the slope of position time graph Identify the instantaneous velocity from the graph Reference to the book: Review page # ……… for the topic Teaching notes for grade 10 P a g e |1 A. Position-Time Graph To represent motion you can use motion diagram, tables and Graphs Representing motion by graph: The motion of an object can be represented by a graph. The graph is a pictorial representation of change of one physical quantity with respect to the other. In a position-time graph the two quantities are `position` and `time` in which the time is always plotted on x-axis and position on y-axis. B. Plotting Position Time Graph The data listed in Table 1 can be presented on a position-time graph, in which the time data is plotted on a horizontal axis and the position data is plotted on a vertical axis. To draw this graph, first plot the runner's positions. Then, join these points by drawing a straight lines that best fits the points. Sample 1 plotting: X =0m i X = ……m f 2 C. Reading Position Time Graph. Part (1) The data plotted in graph can be presented on a position-time table. Initial and final position can be determined also form the graph. Sample 2 Plotting: Label the X- axis and Y- axis, the Use this table to plot the points on the graph and join these points by drawing a straight line. X = ______________________ i X = ______________________ f Sample 3 Reading graph: Complete the table of position-time for each graph and find Xi and Xf. 3 X = ______________________ i X = ______________________ f ACTIVITY: Q1: Consider a man riding on a bicycle. The table below shows his position at different times. Label the X- axis and Y- axis, the Use this table to plot the points on the graph and join these points by drawing a straight line X = ______________________ i X = ______________________ f 4 Q2: Complete the table of position-time for each graph and find Xi and Xf D. Reading Position Time Graph. Part (2) From Position Time Graph, you can: Determine the instantaneous position of the object at specific time or determine the time taken to reach at specific position Predict the expected positions or time intervals according to the pattern of the linear graph. Find total distance and total displacement. Sample 1: Refer to the diagram below to answer questions. 1. What is the position of the object at 3 s? ____________ 2. How much time has passed when the object is at 2 m? ________________ 3. If the object continues at this speed, when will the object reach 40 m? _____________ 4. If the object continues at this speed, where will the object reach at 10 s? ___________ Sample 2: Find the total distance and total displacement from the graph: 5 A. Total distance: ______________ B. Total displacement: _____________________ ACTIVITY 2: Student A: Student B: Find the total distance and total displacement from the graph. Find the total distance and total displacement from the graph. Total distance: _______________________ Total distance: _______________________ Total displacement: ____________________ Total displacement: ____________________ E. Slope of Position Time Graph: The slope of a line is the ratio of the “rise” (vertical change) to the “run” (horizontal change) of the line. In a position time graph the slope of the line is average velocity ( ). Slope is the rise/run of a line. The motion of more than one object can be graphed on a single position-time graph. = 6 E.1: Interpreting Position-Time graph 1. Steepness of slope on Position-Time graph: The steepness of a line on a graph is called slop Steep slope = higher velocity Shallow slope = less velocity E 2. Positive and negative (Slope) velocity The motion of an object can be expressed as moving with positive velocity, negative velocity or at rest. Consider the example of a moving car. A. This car is moving towards right or east, it has positive velocity. B. This car is moving towards left or west, it has ___________________. C. This car is at rest. It has ___________. No change in the position 7 3. Intersection on Position vs time: Intersection in Position vs time indicates that the two objects share the same position at that instant in time, Ex: Overtaking cars. Sample 1: Two drivers (driver A and driver B) are traveling in opposite directions on a long, straight road. Their motions are represented by the position-time graphs of each, shown below. I. II. III. IV. 8 How long had driver A already been driving when driver B started to drive? __________ How long had driver A been driving when she was 30 km away from her starting point? __________ Which driver is faster? _________ What happens at point? __________ ACTIVITY 1: Three friends run a race. The graph below describes their motion A. Who runs at the slowest velocity? ________________________ B. Who runs at the fastest velocity? ________________________ C. Who is at rest? ________________________ D. What happens at point I and M? ________________________ E. Who passes B path first and when? ________________________ F. Who travels the farthest after 40 s? ________________________ M I E.2 : Solving for slope = Average velocity Recall: In a position time graph the slope of the line is average velocity ( ). Slope is the rise/run of a line. Sample 1: 1. Solve the slope of A. 2. 3. 4. 5. 6. 9 ______________________________________________________________________________ Solve the slope of B. ______________________________________________________________________________ Solve the slope of C, Describe its motion. ______________________________________________________________________________ Solve the slope of D. ______________________________________________________________________________ Based on the slope, at which time it is moving the fastest? _______________________________ Based on the slope, at which time it is at rest? ________________________________________ ACTIVITY 2: Student A: Student B: 1.) Solve the slope of A and C. Which one is faster? 2.) Solve the slope of E and H. Which one is faster? 3.) Solve for B and F. Describe the motion for both. 4.) Solve for D and G. Describe the motion for both. 10