Projectile Motion 1 Projectile n An object that
Projectile Motion 1
Projectile n An object that moves through the air only under the influence of gravity after an initial thrust n For simplicity, we’ll use 9. 8 m/s 2 for gravity. n Trajectory – path of a projectile 2
n The vertical and horizontal components of a projectile are independent of each other n If 1 ball were dropped another ball launched forward from the same height, they would hit the ground at the same time. 3
Video Break n. Mythbusters 4
Force vectors for projectiles n. Draw both horizontal and vertical vectors 5
Vertical d=½ 2 gt V = gt Horizontal d = Vt V = d/t
Horizontally launched cannonball 7
Non-horizontally launched cannonball 8
Vertical Component n Distance nd = Vit + ½ gt 2 nd = ½ gt 2 n Velocity n. Vf = Vi + gt n. V = gt *Vi is 0, so it cancels! 9
Horizontal Component n. Distance nd = Vt n. Velocity n. V = d/t 10
Example) A stone is thrown horizontally at 15 m/s from the top of a cliff 44 m high. na) How long does it take to fall? nd = ½ gt 2 n 44 = ½ (9. 80)(t 2) n 44 = 4. 90( t 2) n 8. 9796 = t 2 nt = 3. 0 s 15 m/s 44 m 11
Example) A stone is thrown horizontally at 15 m/s from the top of a cliff 44 m high. n b) How far from the base of the cliff does it land? nd = Vt nd = (15)(3. 0) nd = 45 m d 12
Example) A stone is thrown horizontally at 15 m/s from the top of a cliff 44 m high. nc) What is its vertical speed when it hits the ground? n. V = gt n. V = (9. 80)(3. 0) n. V = 29. 4 m/s 13
Example 2) A ball is thrown at a horizontal speed of 18 m/s. It’s flight time is 4. 6 seconds. n. How high does the ball go? nd = ½ gt 2 2 nd = ½ (9. 80)(2. 3 ) nd = 25. 92 m 14
Example 2) A ball is thrown at a speed of 18 m/s. It rises and falls in 4. 6 seconds. n. How far away does it land? nd = Vt nd = (18)(4. 6) nd = 82. 8 m 15
Example 2) A ball is thrown at a speed of 18 m/s. It rises and falls in 4. 6 seconds. n. What is its vertical speed when it hits the ground? n. V = gt n. V = (9. 8)(2. 3) n. V = 22. 54 m/s 16
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