1) The document discusses modeling motion using distance-time graphs and calculating average speed using the equation average speed = change in distance / change in time. 2) It provides examples of how to use the average speed equation to calculate speed given distance and time, and examples of how to solve the equation for distance or time. 3) The key differences between average, instantaneous, and constant speed are explained.

1. Good Morning!Today we will:review distance v time graphs as a model for motionlearn to calculate average speedPlease do NOW:get a textbook, your lab book & your spiralget out something to write with

2. Warm-UpDraw the following graph in your lab book (include labels) and explain (in words) the motion it depicts

3. Modeling Speed: Equationsaverage speed can be found using the equation sav=where sav = average speedΔd = change in distanceΔt = change in timeΔdΔt

4. Modeling Speed: EquationsSample Problem: If you drive a distance of 400 miles in 8 hours, what is your average speed?

5. Average speedAn average of 50 mi/h does not tell you your fastest speed or your slowest speed.It does tell you that over a certain amount of time, you covered a specific distance

6. Average SpeedFor instance, you probably weren’t traveling at a speed of 50 mi/h in your neighborhood, and you stopped at traffic lights, and on the freeway, you probably traveled faster than 50 mi/h.

7. Average Speedaverage speed: total distance traveled in a specific amount of timeinstantaneous speed: the speedometer reading at any given instantconstant speed: speed that does not change over a period of time

8. EquationsThe formula for average speed ( sav = Δd/Δt) can also be used to solve for distance or time.

9. Sample ProblemYou are traveling at 50 ft/s (about 35 mph) and your reaction time is 0.2 s. Calculate the distance you travel during your reaction time.

10. Equation Solving StrategyIn physics, when you do calculations it is very important to pay attention to the units you are using.Always carry your units through the problem!ALWAYS. REALLY. I’M NOT KIDDING.

11. Sample Problem #3In an automobile collision, it was determined that a car traveled 150 feet before the brakes were applied.If the car was traveling the speed limit of 40 mi/h (60 ft/s), what was the driver’s reaction time?