Rectilinear Kinematics Ch 2. of Arons’ Teaching Introductory Physics

Rectilinear KinematicsCh 2. of Arons’ Teaching Introductory Physics Reasons behind failure to learn Helpful instructional strategies ~ summarized by Carl J. Wenning ~

Misleading equations • t and d are not the same in all equations • t and d denote time and position in one case, change of time and position in another, and time and distance in yet another of the equations • Students are rarely informed of the distinction! • Do you know the difference?

Similarly • and • v (instantaneous) • v (average) • Which is which, and does it make a difference? • A bicyclist rides up a hill at 1 m/s and down the hill at 3 m/s. The distance is the same both ways, 100 m. What is the average speed of the bicyclist?

Confusing terminology • distance versus displacement • velocity versus speed • definition of average velocity • instantaneous vs. average velocity • acceleration versus deceleration

Solution 1: positions and clock readings • Start with “position” and “clock reading”

Solution 2: distinguish between variables • be very careful introducing concept of average velocity • average velocity is a rate that is an average per unit of time for changing rates of speed.

Solution 3: use motion graphs & maps • broadly interpret velocity versus clock reading graphs

Solution 4: miscellany • instantaneous velocity • sign conventions • acceleration

Solution 5: preconceptions • Identify, confront, resolve • Top of the flight path

Solution 6: solving exercises • Exercise-solving routine • Equation finder • Solution framework: • Set up position line & draw diagram • Identify + and - directions • Translate verbal statement into symbols • List all knowns and unknowns with variables • Find pertinent kinematic equation • Make necessary calculation • Interpret the results

Rectilinear Kinematics Ch 2. of Arons’ Teaching Introductory Physics