Breaking initial velocity into horizontal & vertical components
Launching a projectile at an angle splits its initial velocity into horizontal (Vix) and vertical (Viy) components — together they determine how far and how long it flies.
A soccer player kicks a soccer ball twice with the same force and contact time. One kick was at an angle of 20° and the other kick was at an angle of 40°. Which soccer ball went further? (greater dx)
How many things would you have to get right to make this work?
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(not 0° or 90°)
Projectile Path is Parabolic
Baseball Throw
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Victoria Lollo - Class of 2007
Projectile fired at 5 m/s:
Projectile fired at 5 m/s.
Find: Vix and Viy if θ = 0°.
Projectile fired at 5 m/s.
If θ = 90°, then…?
If angle is not 0° or 90°, the initial velocity is part vertical and part horizontal.
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*** To understand this type of motion we must breakup the velocity into horizontal and vertical parts (components)
V - velocity of projectile fired
Vix - initial V in x direction
Viy - initial V in y direction
Since…
cosθ = A/H = Vix/V
Cross multiply:
Since…
sinθ = Opp./Hyp. = Viy/V
Cross multiply:
During the time the ball is in the air, how many times is the vertical velocity zero?
Ex) A baseball is thrown upward at an angle of 30.° and a velocity of 6.0 m/s.
Find: the initial horizontal & vertical components of the baseball's velocity.
Vertical Component
Horizontal Component
dx = Vxt (memorize)
ay = -9.8 m/s² Ascending (down –)
ay = +9.8 m/s² Descending (down +)
Vy at Peak = 0
tpeak = ½ ttotal • V = at • dx = Vxt
What angle produces the greatest range?
Don Ion
Name another angle that will give the same range (dx)
Minimum Range
Maximum Range
Angle with Longest
Time in Air?
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Ex) Which angle of projection causes a projectile to stay in the air longer?
50 or 70 degrees?
Ranking Task
1. A rock is thrown at various angles but with the same initial velocity.
2° 70° 20° 5° 60°
Find: rank the angles above from smallest horizontal displacement (dx) to the greatest.
NYSSLS Reading Passage · 2D Motion
Newton's Cannonball: The Thought Experiment That Explained Orbits
Open Reading Passage →5 quick questions — pick an answer to see if you’re right.
1. A baseball is thrown at 6.0 m/s at 30.° above horizontal. What is the initial vertical component of its velocity?
2. A projectile is launched at 10. m/s at 60.° above horizontal. What is its initial horizontal component?
3. Ignoring air resistance, what launch angle gives the greatest range over level ground?
4. A rock thrown at 30° lands a certain distance away. At the same speed, which other angle gives the same range?
5. At the very top of an angled projectile's path, which is true?