UWEC PHYS 211 - Projectile Motion and Example Problems (3 pages)

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PHYS 211 Lecture 8 Outline of Last Lecture I Free fall II Vectors a Components of Motion b Addition and Subtraction Outline of Current Lecture I Projectile Motion II Practice Problems Current Lecture I 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 other II Example Problems for Projectile Motion 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 D they all have the same hang time because all of them reach the same height E The cannonball on the moon will be accelerated downward at a rate of approximately 1 6 of the rate of gravity on earth A punt has a hang time of 4 2s and travels 40m What s the initial velocity xi 0m xf 40m vix vif ax 0 m s2 t 4 2 s Vix d t xf xi t 9 5 m s yi 0m yf yiy yif ay 9 8m s2 t 4 2 s To find velocity in the y direction split the problem in half at the top t 2 1s and v fy 0 Vfy viy at Viy at Viy 20 6m s A 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 68m xi 0m xf 18 4m vix 40 2m s vif 40 2m s ax 0 m s2 t t d v 0 46s Yf yi viyt at2 1 68m 9 8m s2 0 46s 2 0 64m Yes it will be a strike because 0 64m 0 45m yi 1 68m yf yiy 0m s yif ay 9 8m s2 t