PHY 102 1nd Edition Lecture 7 Outline of Last Lecture I. Blue Book ProblemsOutline of Current Lecture I. MotionII. Uniformly Accelerated Motion (UAM)III. Blue Book 3.1Current LectureI. Motion (Rectilinear)a. The simplest kind of motion takes place on a straight lineb. Three quantities that describe this motioni. Distance (displacement)ii. Speed (velocity)1. meters/second (m/s)iii. Acceleration(Quantities in bold can be positive or negative)c. The simplest kind of rectilinear motion is uniform motion, in which velocity does not changei. x = vtii. speed = distance/time1. v = x/tiii. 1 mile per hour = 1 mile/1 hr = 1610 m/3600 s = 0.4472 m/s1. Example: IL speed limit = 70 mph = 70 * 0.4472 = 31.3 m/siv. The best way to learn rectilinear motion is graphs1. Plot velocity versus time on a graph2. Distance, velocity, and acceleration can be easily identified on such a graph3. Uniform motion (velocity as a function of time)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. How do you represent the distance on such a graph? How do you find the distance covered in 15s?8 * 15 = geometry --> height * widthAREA4. “Area-as-distance” is not limited to uniform motion. It can be used in general.a. Of course you can’t multiply velocity by time because velocity keeps changing in a general motionb. But if your time interval is very short, velocity is almost constant during that time, and you can use the distance-as-area ideai. Break up the (large) time interval into a lot of very short/small intervalsii. Calculate the distance for each short interval and add them all together5. So far, we have learned how to find the velocity and distance for a moving objecta. For velocity, read off the plot value. For distance, measure the area under the v-t curve.6. What about acceleration?a. acceleration = change in velocity/timea = ∆v/∆tUnit = meters/second2 (m/ss)b. Instantaneous acceleration a = ∆v/∆t, ∆t is very smallc. Remember ∆v can be either positive or negativei. a > 0 means velocity increases (speeding up)ii. a < 0 means velocity decreases (slowing down)d. Graphically, tangent line is the timeII. Uniformly Accelerated Motion (UAM)a. Acceleration does not changeb. Slope does not change (straight line)i. y = mx + bc. v = at + vod. distance = area of trapezoid = area of rectangle + area of trianglei. area of rectangle = tvo = votii. area of triangle = ½t (v – vo) = ½at2e. x = vot + ½at2i. a can be either positive or negativeIII. Blue Book