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Aim: How can we solve problems dealing with horizontally fired objects?

Aim: How can we solve problems dealing with horizontally fired objects?. Do Now: An object falls freely for 75 m. How long does it take to reach the ground? How fast is it moving upon impact?. v f = v i + at v f = (0 m/s) + (9.8 m/s 2 )(3.9 s) v f = 38.3 m/s. d = v i t + ½at 2

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Aim: How can we solve problems dealing with horizontally fired objects?

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  1. Aim: How can we solve problems dealing with horizontally fired objects? Do Now: An object falls freely for 75 m. How long does it take to reach the ground? How fast is it moving upon impact? vf = vi + at vf = (0 m/s) + (9.8 m/s2)(3.9 s) vf = 38.3 m/s d = vit + ½at2 -75 m = (0 m/s)t + ½(-9.8 m/s2)t2 t = 3.9 s

  2. Demo A bullet is shot out horizontally from a gun. At the same time and from the same height, a second bullet is dropped to the ground. Which hits the ground first?

  3. They hit at the same time!

  4. What goes on vertically has no impact as to what goes on horizontally What do you notice about the horizontal motion and the vertical motion?

  5. Used for problems such as: • Horizontally fired objects such as bullets, cars driving off of cliffs, etc. • Dropping an object while moving, such as a bomb or humanitarian package. • The shape of the path is a parabola

  6. Car off Cliff

  7. Separate Components • Velocity, acceleration, and distance have both horizontal (x) component, and vertical (y) component

  8. Horizontal Components • Horizontal velocity is constant: • There is no horizontal acceleration: a = 0 m/s2 • Horizontal distance (also known as the range) is found using this equation:

  9. Vertical Components • For the vertical motion, the object is in free fall: vi = 0 m/s • Vertical acceleration = gravity: a = g = -9.8 m/s2 • Vertical distance (also known as the height) is found using the distance equation: d = vit + ½at2

  10. Time • Vertical and Horizontal time are equal:

  11. Separate your information according to vertical and horizontal x y vi = 0 m/s a = -9.8 m/s2 d =height d = range t = t

  12. Example • Thelma and Louise drive off a cliff 75 m high with a speed of 15 m/s. • How long does it take to hit the ground? x y vi = 0 m/s a = -9.8 m/s2 d = -75 m t = ? t = ?

  13. Determine which column you have enough information so that you can solve the problem. The vertical column has enough. Do not mix and match vertical and horizontal information!!! d = vit + ½at2 -75 m = (0 m/s)t + ½(-9.8 m/s2)t2 -75 = -4.9t2 15.3 = t2 3.9 s = t

  14. x y vi = 0 m/s a = -9.8 m/s2 d = -75 m t = 3.9 s t = 3.9 s d = ? • Howfar from the base of the cliff do they land? d = 58.5 m

  15. x y vi = 0 m/s a = -9.8 m/s2 d = -75 m t = 3.9 s vf = ? t = 3.9 s d = 58.5 m • How fast are they traveling vertically on impact? vf = vi + at vf = (0 m/s) + (-9.8 m/s2)(3.9 s) vf = -38.3 m/s

  16. Pages 124-129

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