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Projectiles

Projectiles. Bellwork. Complete Wednesday and Thursday ’ s bell work Do not play with materials in basket. To do:. Place the images into 2 categories Projectile Motion Non-Projectile Motion. A Projectile is. An object thrown or launched into the air that is subject only to gravity.

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Projectiles

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  1. Projectiles

  2. Bellwork • Complete Wednesday and Thursday’s bell work • Do not play with materials in basket

  3. To do: • Place the images into 2 categories • Projectile Motion • Non-Projectile Motion

  4. A Projectile is . . . • An object thrown or launched into the air that is subject only to gravity

  5. Projectiles include: • Throwing a baseball • shooting an arrow • hitting golf balls • long jumpers

  6. To do: • Using the materials in your basket, build an apparatus that will launch the marshmallow with a parabolic trajectory • Think about: • How does the velocity of the marshmallow change as it travels through the air? • Is there a difference between the velocity in the x direction and the velocity in the y direction? • What is the only force acting on the cotton ball once it has been launched? • How can you make the cotton ball go higher? Further?

  7. Bellwork 1. What is the acceleration of a tossed ball at the top of its path? 2. How do you find the displacement of an object from a velocity time graph? 3. Draw a position time graph that shows • Object traveling with constant velocity • Object decelerating • Object at rest

  8. Projectile motion • Has both a horizontal and vertical component (part) • These components are independent of one another • http://www.physicsclassroom.com/shwave/projectile.cfm

  9. Trajectory • The path of a projectile is called a trajectory • the shape of a projectile’s path is a parabola

  10. Horizontal motion • A projectile moves forward due to INERTIA • Inertia is the reluctance of an object to change its motion

  11. Horizontal motion • A projectile continues forward at constant speed because no HORIZONTAL FORCE acts on it • The velocity in the horizontal direction remains the same throughout flight

  12. Vertical motion • Gravity pulls on any object and causes it to return to earth • This means that the vertical velocity changes • This motion is just like an object in free fall

  13. Projectiles launched horizontally Half picture projectiles

  14. Projectile Velocity • Separate the motion into x and y components (parts) • When an object is launched horizontally, the VERTICAL velocity is 0 m/s

  15. Vx Actual path vy

  16. The acceleration of the object in the y direction is due to gravity (like free fall) • Use kinematic equations to solve for unknowns in both the x and y directions

  17. Mythbusters • http://www.youtube.com/watch?v=abUBrQmI33Q

  18. Useful Distance Equations For horizontal distance: OR This equation for average velocity can also be used for finding velocity in the horizontal (x) direction.

  19. Useful Distance Equations For Vertical Distance

  20. Useful Velocity Equations For vertical velocity

  21. Useful Velocity Equations Remember that horizontal velocity remains the same throughout flight

  22. Time of flight • The time of flight can be determined using kinematic equations used for free fall. Remember, the only force acting on an object once it has been launched is gravity.

  23. A stone is thrown horizontally at 15 m/s from the top of a cliff 44m high. A. How long does the stone take to reach the bottom of the cliff? B. How far from the base of the cliff does the stone strike the ground? Example:

  24. Time Solution

  25. Distance Solution

  26. Given Information

  27. Time Solution -44m = 1/2(-9.8m/s2)t2 t = 3 s

  28. Distance solution: d = vt d = 15 m/s x 3.0 s d = 45 m

  29. Upwardly Launched Projectiles (at an angle) • The result of simultaneous horizontal and vertical motion is a curved path

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