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Projectile Motion

Projectile Motion. Rules. There are only really a few rules:. All projectiles are freefalling objects. The horizontal motion is totally unaffected by the freefall motion!. Since there are no forces acting on it, horizontal motion is at constant speed!. And now….

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Projectile Motion

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  1. Projectile Motion

  2. Rules There are only really a few rules: All projectiles are freefalling objects The horizontal motion is totally unaffected by the freefall motion! Since there are no forces acting on it, horizontal motion is at constant speed!

  3. And now…

  4. Horizontal Projectiles • Horizontal Projectiles are easiest to work with • only formula used in horizontal (x) direction is: vx = dx/ t

  5. Horizontal Projectiles • Horizontal Projectiles are the most basic • only formula used in horizontal (x) direction is: vx = dx/ t constant speed!

  6. Horizontal Projectiles • vertical (y) direction is just freefall • all of the initial velocity is in the x direction • So, • viy = 0 • since viyis in freefall, • a = -9.8 m/s2

  7. ExampleA person decides to fire a rifle horizontally at a bull’s-eye. The speed of the bullet as it leaves the barrel of the gun is 890 m/s. He’s new to the ideas of projectile motion so doesn’t aim high and the bullet strikes the target 1.7 cm below the center of the bull’s-eye. What is the horizontal distance between the rifle and the bull’ s-eye? start by drawing a picture: label the explicit givens

  8. ExampleWhat is the horizontal distance between the rifle and the bull’ s-eye? givens (separate by direction): want: horizontaldistance

  9. Example which equation do we use? use to find time rewrite equation for t

  10. Example Use t and vx to solve for dx

  11. Non-horizontal Projectiles • vx is still constant • vy is still in freefall • only difference with non-horizontal is…

  12. Non-horizontal Projectiles • Angled Projectiles require a little work to get useful vi • vi has an x and y component • need to calculate initial vx and vy

  13. Breaking up a vector • every vector has 2 components to it • a horizontal component • a vertical component • they add up to the total

  14. Breaking up a vector SOHCAHTOA opposite hypotenuse adjacent

  15. Breaking up a vector SOHCAHTOA need to find θ? opposite hypotenuse adjacent

  16. Non-horizontal Projectiles • need to calculate initial vx and vy

  17. relief

  18. Visualizing Projectiles • first enter vectors • focus on vx vx is constant the whole flight!

  19. Visualizing Projectiles no vy at the top! • first enter vectors • focus on vx • focus on vy vy decreases as it rises! by how much per second?

  20. Visualizing Projectiles

  21. Varied Angles • which projectile angle shoots highest? • larger θmeans faster viy • which projectile angle shoots farthest? • 45° has perfect balance of fast vxand long flight time.

  22. Let’s analyze the jump

  23. Try Graphing It Go to pg. 331

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