AP+Physics

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=AP Physics=


 * __Important Announcements__**: For those of you taking the AP exam on Monday, take the weekend to look over and study the concept review sheets from each chapter. You should have chapters 1-12 except for chapter 9. If you are missing one, let me know through the discussion board and I will attach the document to the page for you. REVIEW REVIEW REVIEW!

__Multiple Choice Questions__: Due Monday (5/10) For Physics B Exam questions, skip 7, 19, 26, 27, 28

"With great power comes great responsibility" - Ben Parker Here are the answers to the multiple choice questions. Use them wisely and to check your answers.

Homework Problem: Due Tuesday (5/4) A 0.500 kg block is pushed down on a vertical spring with a force constant k = 150 N/m so that the spring is compressed 0.250 m. If the block is released from rest and shot upward from the spring, to what vertical height will the block rise? Also, how much time does it take the block to reach that height after leaving the spring?

__**Important Announcements**__: There is a Macgruber movie in the making! Fo realsies!

__Homework Problem__: Due Monday (4/19) A man with a jar of peanut butter is speeding in a car with an initial velocity of - 16.67 m/s **//j//**. The car is 600 m away from a four-way intersection. On the road that intersects, a man with a chocolate bar is traveling with a velocity of - 22.22 m/s //**i**//. In a sick turn of events, the cars collide at the intersection and the chocolate bar gets stuck in the peanut butter. Both men died on impact, according the the first-responder, Officer Reeses.

(A) Initially, how far away from the intersection was the man with the chocolate bar?

(B) Given the distance from part (A), if the man with the chocolate bar started from rest, what constant acceleration would he need if he is to still collide with peanut-butter-jar guy?

__Homework Problem__: due Friday (4/16) Projectile 1 is launched off a cliff with an initial speed of 100m/s at an angle of 45 degrees. Three seconds later, a second projectile is launched off the same cliff. The instant that the first projectile has the same height as the cliff (on its way down), the second projectile passes infinitesimally close to the first projectile without touching it (assume the two trajectories intersect at a particular time, but ignore the physical collision between the objects). Answer the following questions //qualitatively// (no numbers).

(A) Compare the initial y-components of the velocities of the two projectiles when they're launched.

(B) Compare the maximum heights of the two projectiles and the total time spent by each projectile in the air.

(C) Compare the x-components of the velocities of the two projectiles.

(D) Which projectile has the longer range?

media type="custom" key="5839213" Hey gang! Don't forget! There's a test tomorrow afternoon (during 3rd period, in place of 7th period)! We will continue to review during 2nd and 3rd period in the morning. In the meantime, try this sample free response problem. We'll discuss the answers tomorrow in class. You can either post your answers or questions to the discussion board. Hope you enjoyed the video!

__Problem__: A mass //m// is attached to a horizontal spring of spring constant //k//. The spring oscillates in simple harmonic motion with amplitude //A//. Answer the following in terms of //A//. (Algebraic answers)

(A) At what displacement from equilibrium is the speed half of the maximum value?

(B) At what displacement from equilibrium is the potential energy half of the maximum value?

(C) When is the mass farther from its equilibrium position, when its speed is half maximum or when its potential energy is half maximum?

(D) Briefly explain why the speed of the mass at half maximum is not at 1/2 A.

__Hey all__: Here is another video for you! Sorry it's not YouTube, but they were giving me some copyright hogwash. Also, if you see the red x in the upper right corner of the image, then you will need to click the pop-up bar and select 'run activx control.'

media type="file" key="Chicks Part II.wmv" width="300" height="300" __Announcements__: Chapter 11 homework assignments will be due Thursday before the test.

__Review problems__:

1. A painter climbs up a ladder that is 20 m long and weighs 400 N. The ladder is leaning against a smooth wall with an angle of 60 degrees. The painter weighs 700 N. If the coefficient of static friction is 0.35, find how far up the ladder the painter can climb before the ladder begins to slide.

2. A 1kg block rests on a frictionless table and is connected to a string which passes over a 0.5 kg pulley (a disk) and is tied to a 3kg block which is hanging over the edge of the table. Determine the acceleration of both blocks.

__3/22 Homework__: 1. The International Space Station (ISS) is in "low earth orbit" and is, on average, at a height of 350 km above the Earth's surface. Determine the period of the orbit in minutes.

2. Halley's comet has an orbital period of 75.6 years. At its perihelion (the closest approach) it comes within 0.570 AU of the Sun. What is the aphelion of the comet's orbit? (1 AU is an "astronomical unit" and is defined as the mean-distance btwn the Earth and the Sun. 1 AU = 1.50 x 10^11 m)

3. The ISS orbits at 350 km above Earth's surface. It's average orbital speed is 7,701 m/s. If the station expanded its orbit an additional 1,000 km, what would be its new orbital speed? (Solve this problem using the conservation of energy for orbits)

Achtung Klasse! Since the chapter on planetary motion is relatively short and the scores on Chapter 10's test were unspeakable, you can expect to see additional problems from chapter 10 on the next test. Accordingly, you should make sure that you have successfully completed the 3/11 HW assignment. You may still post questions to the website at any time. Also, if the website is not convenient for you, I am available before and after school. The 3/17 HW assignment still stands as well as the 3/19 HW assingment. I will be collecting those sometime next week; I'll announce it in class a few days before they're due. So in the meantime, if you have trouble with the homework, please use the website. Remember, even if I'm not responding right away, anyone else in the class can offer tips (like Laux... he crushed that last test).

Tschuss!

__Check it__: We are at the end of chapter 10 and the test is approaching like an unstoppable rebel force. That being said, I have prepared some review material. "Handout 10.0" is an outline of the chapter that includes relevant equations. "Review Concepts Chapter 10" is an outline that lists the concepts from the chapter. "Handout 10.1" is a list of problem-solving tips for objects in complete equilibrium and objects experiencing a net torque.







__Answer to 3/11 homework__: wf = 5 rad/s and Kr = 2 J. We will not be going over this in class, so if you have questions, use the discussion board.

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__Homework__: Due Thursday (3/11) __Directions__: Post your answers or questions to the discussion board for tomorrow. __Problem__: Suppose a vertical hanging rod (as shown below) has a mass of 0.45 kg and a length of 0.80 m. The rod is struck on the bottom edge by a 0.10 kg lump of clay traveling horizontally as shown below.



a.) Use __conservation of angular momentum__ to determine the angular velocity acquired by the rod/clay as a result of the collision. b.) How much rotational KE does the rod/clay system possess immediately after the collision?

__Homework__: Due Monday (3/8) __Directions__: Post your final answers only for Friday's free response problem.

AP Physics, Due to the overwhelming negative responses to the second video, I offer a sincere apology. Please know that my efforts at humor have entered a decline and that I formally announce my retirement from the video-making business. I was planning to offer a video apology, but we all remember how the last video turned out. Thank you for your time and understanding.

Professionally yours, W.

__Homework__: Due Tuesday (3/2) __Directions__: Complete the problem on a separate sheet of paper, post your answers or questions and turn it in Tuesday. You can post questions to the discussion board. __Problem__: A rotor turning at 1,200 rev/min has a diameter of 5 cm. As it turns, a string is being wound onto its rim. What length of string will be wrapped around in 10 seconds?

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Test Updates!!! Yes the momentum test is on Monday (2/22), but please watch the following video and some time on Saturday, I will post a sample test to the wiki. Don't forget to look over your past homeworks and the review handouts that you received Thursday (they're posted here too). You can always just post a general question and I'll respond as soon as I can. If you still have questions Monday morning, stop in and see me!

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Here is the sample test. It is about 1/2 the length of the actual test, but it is a good scope of the material that you will see on Monday. Remember to continue to look over the review we did in class, your handouts, and your homework. I will post a key a little bit later today. If you have questions, make a new post to the discussion tab and everyone can continue to put their comments/questions in that thread.

Here is an outline for Chapter 8. You can use this as a general review of the concepts and equations that were covered. It is basically the same thing we did in class on Monday (2/15), but since some of you weren't in class that day, here is a copy.



Also, for your downloading pleasure, here is a rapid review of only the concepts from chapter 8.



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Bonus Problem (LAST CHANCE!!! due Tuesday 2/16) __//Directions//__: Post your answer, as a response to my post for 2/15 Bonus. You will also need to turn in your written work in class on Monday.

A tennis ball (m = 57g) is held just above a basketball (M = 590g) with their centers vertically aligned. Both are released from rest at the same time and fall a distance of 1.20 m. -(a) Find the speed of the tennis ball and basketball as they reach the ground. -(b) To what height will the tennis ball rebound? (If the ceiling was not in the way!) You can assume that the collision with the ground instantaneously reverses the velocity of the basketball while the tennis ball is still moving down. Ignore air resistance.

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Homework Problem (due Friday 2/5) //__Directions__//: Post your answer, as a response to my post for 2/5 Homework. You will also need to turn in your written work tomorrow in class.

__Optional Bonus Points__: (due Wednesday 2/3) Complete the example problems that we didn't get to in class. Post your answers to the discussion thread and submit your written work in class. You will receive points for posting and for your written work.

1. A 0.45 kg hockey puck moving 4.8 m/s east has a head-on elastic collision with a 0.90 kg puck initially at rest. What will be the speed and direction of each puck after the collision?

2. A 12g ball is dropped from a height of 1.5m from rest. The ball only bounces back to a height of 0.75m. What is the total impulse exerted on the ball from the floor.

__Weekend Special Edition!__

What happens when an unstoppable force meets an immovable object?

Lightning demo... (see reply to Mincinstheorem question)



Homework Problem (due Friday 1/29) __//Directions//__: Post your answer, along with a justification as a response to my post for 1/29 Homework.

__Problem__: So, I was thinking this morning.... does snow violate the law of conservation of momentum? I simply want your thoughts. Argue your case and we'll talk about it in class tomorrow too. Here are some things to consider: Snow is simply crystallized (frozen) water droplets. Those water droplets are condensed air (from the atmosphere), so technically, the snow was always up there. You can treat the snow as one large system of snow flakes moving collectively towards the ground (n = number of flakes). During a snow storm, there are a lot of flakes heading towards the ground, so the mass of the system is not negligable. Please use the picture to assist your theory....

Kaz, feel free to provide a mathematical proof.



Homework Problem (due Thursday 1/28) __//Directions//__: Post your answer, along with a justification as a response to my post for 1/28 Homework.

__Problem__: A ping pong ball is thrown at a stationary hanging cannon ball (with a mass much greater than the ping pong ball's). After they collide, assume that the ping pong ball bounces away with a final velocity that is equal in magnitude to its initial speed. How will the final momentum of each object compare? Justify your answer.

My Lab Assistant Presenting the Ping Pong Ball:

Homework Problem (due Wednesday 1/27) __Directions__: Solve the problem and post the answer under the Discussion tab. If you cannot solve the problem, post a specific question that you need answered in order to solve it. This way anyone in the class can try to answer your question.

__Problem__: An ice skater with a mass of 65 kg is skating with an initial velocity of 3.0 m/s. In the skater's path is a child with mass 25 kg that is sitting on the ice. After they collide, the child is deflected 60 degrees to the left of the skater's original path and the skater is deflected 30 degrees to the right of the original path. Determine the final speed of both the child and the skater.