PHYS 211 Lecture 8 Outline of Last Lecture I. Free fallII. Vectorsa. Components of Motionb. Addition and SubtractionOutline of Current Lecture I. Projectile MotionII. Practice ProblemsCurrent LectureI. Projectile Motion***A projectile launched in an arbitrary direction may have initial velocity components in both x and y directions but it is still accelerated downward***Note that velocity in the x direction does not change because the components of velocity in the x and y direction are independent of each otherII. Example Problems for Projectile MotionThese 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.D) they all have the same hang time because all of them reach the same heightE) The cannonball on the moon will be accelerated downward at a rate of approximately 1/6 of the rate of gravity on earthA punt has a hang time of 4.2s and travels 40m. What’s the initial velocity?xi = 0m yi = 0mxf = 40m yf = ?vix = ? yiy = ?vif = ? yif = ?ax = 0 m/s2ay = -9.8m/s2t = 4.2 s t = 4.2 sVix = d/t = (xf-xi)/t = 9.5 m/sTo find velocity in the y direction, split the problem in half – at the top, t = 2.1s and vfy = 0. Vfy = viy + atViy = -atViy= 20.6m/sA baseball player throws a 90mph pitch from a height of 5ft 6in. The distance to the plate is 18.4m. Will it be a strike?Bottom of strike zone = .45m 90mph=40.2m/s 5ft 6in = 1.68mxi = 0m yi = 1.68mxf = 18.4m yf = ?vix = 40.2m/s yiy = 0m/svif = 40.2m/s yif = ?ax = 0 m/s2ay = -9.8m/s2t = ? t = ?t = d/v = 0.46sYf = yi +viyt + ½at2 = 1.68m + ½(-9.8m/s2)(0.46s)2 = 0.64mYes it will be a strike because
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