1. DAY 14 THE NEXT THREE DAYS Today (M/T): We finish discussing projectiles and kinematics You get to internalize a lot of the conceptual nuances of the ideas of X and Y motion You show you are good at applying the math Next Time (W/R): We have a lab period for the formal penny lab Our 3 rd Session (F/M): We have our 3 rd quiz: On some kinematics, but mostly projectiles, vectors, and graphs of them.

2. DAY 14 LETS BEGIN! TODAY AT A GLANCE: 1) I answer HW questions 2) HW finalization 3) Conceptual Prep: Understanding how to study and what to look for in future quizzes We do some questions to see what we need to focus on 4) We conclude about projectiles 5) We apply the mathematics on the boards, end up with no homework to do for this class!

3. A HW TO HELP YOU OUT I made a video explaining it. Any questions or solutions you want to see/explained? I also did 2 type of math questions on the pre- class video to give you an idea of how to attack and organize your thoughts through math.

4. LETS DO SOME HW In that case, get out your last 3 HW’s (Day’s 11- 13). Using only those, answer the questions given to you for your 2 nd AP Homework Quiz

5. C ONCEPTUAL P REP Huddle with your partners, you have 6 conceptual questions to answer in 18 minutes. Every question needs an answer AND an explanation. Lets set the clock…

6. IF THIS WERE A QUIZ…. How would you have done? Lets go over each, answer AND explanation. Take notes to yourself on this, and if you have a question or want a different explanation… SPEAK UP!

7. T RUE /F ALSE : I T IS POSSIBLE TO HAVE A CONSTANT SPEED BUT STILL BE ACCELERATING ? TRUE Since velocity has both MAGNITUDE and DIRECTION, changing one means the velocity changed. Which means that changing direction while keeping the magnitude (aka SPEED) the same is an acceleration. Called a CENTRIPEDAL acceleration.

8. A The resultant of two vectors is by pythagorean theorm. If one is not zero, then the result must have a value. This is NOT combining two opposite vectors! B: Same idea: the hypotenuse can not be smaller than a leg C: Not always: A can have a X component bigger than B, but B can have a larger Y component to make the resultant larger. D: Magnitude is not direction, so no + or -

9. C Picture time: Think of a horizontal velocity with the pull for gravity at first:

10. C Same X velocity for each the entire time, but the 1 st package will be -10m/s downward faster every second than the other. Which means that with an acceleration, it will be gaining Y displacement faster than the 2 nd package. So the overall distance between them will increase because their Y distances are increasing every moment.

11. B Same X velocity for each. With no acceleration in X, they will be at the same X distance at the same time. Like the cart in hallway demonstration.

12. B This will take some thought. Key points: X velocity is constant for every moment. The Y velocity at the same point will be = to original Vy, but down. When going UP that height, it is slowing down. From start point

13. From J to top (+h), it is slowing down. Lets say it takes.8 seconds. Does it take.8 seconds to go from J to the ground (-h) at –Vo? NO NO NO! Since it is speeding up, it can cover the same distance in less time! So it will not have the same change in velocity as it did from J to top!

14. Going UP h at starting velocity Voy slows to velocity of 0 at top. So it changes by Voy. Going DOWN h at starting velocity of Voy DOWN has the velocity go up. It does NOT change by Voy! It has less time to speed up, so it goes up by less than that!

15. In other words, at the same height as start, it is going Vo. Further down…it is faster. But not double as fast: Vox is unchanged, Voy is not double the velocity. Doing the pythagorean result, you end up larger than before but not double the original.

16. G ENERAL C ONCLUSIONS At the top of a projectile arc, the overall velocity is just the X velocity. The X velocity does not change during the arc. Horizontal initial motion means the Vo in Y is zero. For the same distance up and down, the gain in velocity is NOT the same in Y. At an angle, we must use SIN and COS to find the X and Y components.

17. L ETS D O S OME M ATH …. AND HW 1. Show me the pics/work/etc on the boards, so that you can have a clean sheet to help you in the future. 2. Checking answers is awesome. Look in front OR ask me to do it. 3. If you have a quadratic situation, feel free to use your graph functions or a quadratic solver. Unsure of how to use graphing to do it? Ask me!