1. Projectile Motion Problems
How to solve problems…
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2. Contents
Standard Problem Types
Skills to know
Typical Errors

3. 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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4. 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
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5. Level Ground Projectile
Final vertical component of velocity is equal but opposite to the initial vertical component; this includes the ANGLE from the horizontal.
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6. 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
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7. Maximum Height
Vertical component of velocity is zero at top of trajectory
Set vertical vf = 0
Solve for d
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8. 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
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9. Final Velocity Determine vertical vf
Determine constant horizontal component of v
Use Pythagoras to find the hypotenuse of the final velocity vector
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10. 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
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11. 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).
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12. 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
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