Free Fall Ch 3 3 Free Fall In

Free Fall Ch 3. 3

Free Fall § § In the absence of air resistance, all objects experience the same downward acceleration – whether they are moving UP or DOWN In other words, in a vacuum all objects will fall at the same rate. Free fall acceleration (g) on Earth is -9. 81 m/s 2 Heavier objects do not fall faster than lighter objects

Picture this: n n n A ball is thrown upward with initial velocity (+v) It has (–)a so the speed decreases The ball reaches maximum height and stops for an instant [v = 0 m/s] BUT a = -9. 81 m/s 2 still! If ‘a’ were to change to 0, then the ball would not move from its position. ‘g’ never stops acting on objects! The ball falls back downward with (-)v. Since ‘a’ is in the same direction (-), the speed increases.

Equations: n n Use the same equations as before! Just remember that when an object moves vertically that gravity is causing the acceleration, so on Earth plug in -9. 81 m/s 2 for ‘a’

1. King Kong carries Fay Wray up the 321 m tall Empire State Building. At the top, her shoe falls off. How fast will her shoe be falling just before it hits the ground? d = -321 m vi =0 m/s g = -9. 81 m/s 2 vf = ? Displacement is negative because the object moved down When an object is dropped or falls, the initial velocity is zero

2. A baby blue jay sits in a tall tree waiting for its dinner. As the mother lands on the nest she tries to drop a worm into the chick’s mouth, but misses. The worm falls to the ground in 1. 50 s. How high up is the nest?

3. In order to open a clam it catches, a seagull will drop the clam repeatedly onto a hard surface from high in the air until the shell cracks. If the seagull drops a clam from a height of 25. 0 m, how long will the clam take to fall to the rock below?