Free Fall AP Physics C Mrs Coyle Free

Free Fall AP Physics C Mrs. Coyle

Free Fall n An object moving under the influence of gravity only. n g = -9. 80 m/s 2 , downwards n No air resistance. Free fall is uniform accelerated motion. (g is constant throughout the motion. ) n n Galileo: all objects fall with the same acceleration. He used his ball and channel experiment.

Remember? Galileo’s Ball and Channel Experiment He raised the channel to a level that simulates gravity? http: //www. ifa. hawaii. edu/~barnes/ast 110_06/rots/pftim 19_01. png

Examples: n Dropped n Thrown downward n Thrown upward

Dropped

Dropped from xo = 0 Position (m) o Time (s) Parabola

Thrown upwards from xo = 0 What is the velocity and acceleration at the top of the motion?

Example 1 n A ball thrown vertically upward is caught by the thrower after 20. 0 s. Find (a) the initial velocity of the ball and (b) the maximum height it reaches. n Answer: a) 98. 0 m/s, b) 490 m

Example 2 n Another scheme to catch the roadrunner has failed. A safe falls from rest from the top of a 25. 0 m high cliff toward Coyote, who is standing at the base. Coyote first notices the safe after it has fallen 15. 0 m. How long does he have to get out of the way? n Answer: 0. 51 s

Example 3 n A helicopter is rising and its position is given by h= 4 t 2. After 3 sec it releases a package. How long did it take for the package to fall to the ground? n Answer: 6. 1 sec