2. Free-Falling Bodies

3. Objects Falling Straight Down Points to consider: As the object falls, it has a constant acceleration due to gravity of 9.80 m/s 2. If object is dropped, initial velocity = 0. If object is thrown down, then initial velocity is …….. Final Velocity is velocity just as it hits the ground, not the velocity after it has come to a stop! All 3 acceleration equations can be used, simply substitute the acceleration due to gravity(g) for a in the equations!!!

4. A rock is dropped off of a 30 m high bridge. a) How long will it take the rock to hit the ground below? b) How fast is the rock moving when it hits the ground below?

5. Bear Grylls jumps from a helicopter into a murky swamp. He lands in the water 3.1 s after he jumps out. How high was the helicopter when Bear jumped?

6. A baseball is thrown straight down off of a 50 m high building. The baseball hits the ground with a velocity of 41 m/s. How fast was the baseball thrown?

7. Objects going up and back down!! Points to consider: 1 st —Treat tossed object as two separate paths, one up and one down. Object will have an initial velocity upward! Final velocity on the upward path will be 0. Initial velocity on the downward path will be 0. Final object on the downward path will be = to the initial velocity on the upward path. Time up = Time down Distance up = Distance down

8. t up = t down d up = d down v i = # = v f = # v f = # = v i = # Notice anything about the velocities? Directions are opposite!! Therefore, we must make one of the two directions (-). Because on our EOC, g = +9.80 m/s 2, we will consider down the + direction and up and the (-) direction.

9. A tennis ball is lobbed into the air and remains in the air for 3.5 s. How high did the ball rise?

10. In a baseball game, a batter hits a high fly ball that rises to a height of 40 m. How long did the ball remain in the air?

11. Nick tries to hit a lob shot over a 15 m high tree at the edge of the green at Royal Liverpool. Nick knows from past experience that his lob shot remains in the air for 3.6 s. Does the golf ball have a chance of getting over the tree?

12. A football is thrown straight up with a velocity of 12 m/s. a) How long does the ball remain in the air? b) How high does the ball rise?