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Projectile Motion Problems. How to solve problems…. Contents. Contents. Standard Problem Types Skills to know Typical Errors. Standard Problem Types. Level ground projectiles Down off of a cliff Up onto a cliff Maximum height Time to a specified vertical displacement Final velocity.
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Projectile Motion Problems How to solve problems… Contents
Contents • Standard Problem Types • Skills to know • Typical Errors
Standard Problem Types • Level ground projectiles • Down off of a cliff • Up onto a cliff • Maximum height • Time to a specified vertical displacement • Final velocity Contents
Skills to Know • Resolve components into orthogonal (perpendicular) components • Trigonometric functions • Algebra (better…is BETTER; work on it) • Calculator error (learn to use FEWER key strokes (less brackets, “EE” button for exponents, etc.) • VIFDAT Contents
Level Ground Projectile • Final vertical component of velocity is equal but opposite to the initial vertical component; this includes the ANGLE from the horizontal. Contents
Down Off a Cliff • Find vertical final velocity component with VIFDAT (d is ‘-’)(vf2 = vi2 + 2ad) • Find time of flight using VIFDAT (vf = vi + at) • Use average velocity equation to find the Range (horizontal “d”)d = vavgt Contents
Maximum Height • Vertical component of velocity is zero at top of trajectory • Set vertical vf = 0 • Solve for d Contents
Time of Flight • Determine the displacement from question • Determine if question asks for “on the way up”, “on the way down”, or BOTH • Solve for time using VIFDAT and information in question Contents
Final Velocity • Determine vertical vf • Determine constant horizontal component of v • Use Pythagoras to find the hypotenuse of the final velocity vector Contents
Up Onto a Cliff • Find vertical final velocity component with VIFDAT (d is ‘+’)(vf2 = vi2 + 2ad) • Find time of flight using VIFDAT (vf = vi + at) • Use average velocity equation to find the Range (horizontal “d”)d = vavgt Contents
All Projectiles • Horizontal component of velocity is constant; projectile does not accelerate in the horizontal direction. • Final velocity (the whole vector…not a component) is equal in magnitude, and at the same angle to the horizontal as the initial velocity (just below the horizontal, not above). Contents
Typical Errors • Remember: “vf” is NOT the same as “vertical vf” • Confusion of trig functions used to find horizontal and vertical components of the initial velocity • Vectors in opposite directions NOT given opposite sign (velocity, acceleration, displacement) • Algebra • Calculator errors Contents