grade 9 fourth quarter lesson 1 uniformly accelerated motion in vertical dimension or freefall physics

grade 9 fourth quarter lesson 1 uniformly accelerated motion in vertical dimension or freefall physics

1. Surface Area is more important than mass in determining how fast something falls. When surface area is the same (or similar), two objects of different mass fall at the same rate.

2. FREE FALL is the falling of an object that is only influenced by gravity.  

3. W ith the absence of air resistance, when release from a distance above the ground, all objects regardless of mass tend to fall at the same rate.      

4. A c ce le r a ti o n due to g r a v i t y 9.8 m/s 2

5. A c ce le r a ti o n due to g r a v i t y 9.8 m/s 2

6. d x = v i t + at 2 d y = v i t + gt 2 2ad = - 2gd = -   a = g=  

7. Sign conventions Distances above the origin are positive while distances below the origin are negative. Upward velocities are positive and downward velocities are negative g is always negative. The origin is point of release.

8. Time symmetry – the time required for the object to reach maximum height equals the time for it to return to its starting point. Speed symmetry – shows that any displacement above the point of release, the speed of the body during the upward trip equals the speed during the downward trip.

9. Sample problem: A boy tosses a coin upward with a velocity of +14 m/s. Find (a) the maximum height reached by the coin, (b) time of flight, (c) velocity when the coin returns to the hand.

10. Multiple Choice Read carefully each item then choose the letter of the correct answer. Write your answer in a 1/4 sheet of paper.

11. During each second of its fall, a body in free fall in a vacuum, an empty space where there is no air will drop the same distance will have a constant velocity will have the same speed d. will have the same acceleration

12. 2 . A rock is dropped out of the window of a moving car. At the same time, a ball is dropped from rest from the same height. Neglecting air friction , which will reach the ground first? Rock will hit the ground first b. Both will hit the ground at the same time c . ball will hit the ground first d . Neither will hit the ground

13. 3. A volleyball is tossed vertically upward, with an initial velocity of 5 m/s and caught back at the same level as when it was thrown. What is the velocity of the ball at that point? 0 m/s c. – 9.8 m/s – 5 m/s d . – 9.8 m/s 2

14. For items 4 and 5, refer to the situation below. Maria throws a ball straight up with an initial velocity of 10 m/s. 4.What is its velocity when it returned to the elevation from where it was thrown? - 10 m/s c. 0 m/s - 9.8 m/s 2 d. - 9.8 m/s

15. For items 4 and 5, refer to the situation below. Maria throws a ball straight up with an initial velocity of 10 m/s. 5. What is its acceleration at the highest point? a. 10 m/s 2 c. 9.8 m/s 2 b . 0 m/s 2 d. - 10 m/s 2

16. Problem Solving Solve for what is asked and answer the question. Show your complete solution. (5 pts.) Given – 1 pt Process – 3 pts Final answer – 1 pt If a ball is dropped from a height of 1.5 m, determine the (a) time for the ball to fall to the surface. (b)What is its final velocity?

17. ASSIGNMENT A . Research about Felix Baumgartner, a Redbull athlete, who recently set several world records dealing with free fall then answer the following questions. What did he do and records did he set? Felix jumped from 39.045 m and, over the course of the 4:19 fall, achieved a maximum speed of 1,342.8 km/hr. Assuming he started from rest, how long did it take him to reach his maximum speed (neglect air drag)? Read about motions in two dimensions and give examples of these motions.