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Everything posted by FizziksGuy

  1. FizziksGuy

    Feynman vs Lewin.

    CalTech event in the spirit of Feynman's vision occuring today... http://tedxcaltech.com/
  2. http://science.discovery.com/brink/quiz/what-scientist-quiz.html You Are Edison... Brilliant, methodical, patient. Edisons believe in using teamwork to solve problems. They see the value in testing 800 compounds before finding the right one. It may not be as sexy as getting it right on the first try, but without thinkers like you, we'd all be in the dark. What does the quiz say about you?
  3. As many of you may have noticed, APlusPhysics has been rather slow as of late. In an attempt to remedy the situation, we have switched our hosting to a "grid hosting" arrangement, in which a number of servers provides simultaneous hosting and can allocate needed resources to accommodate spikes in activity on our website. You should see this in a speed improvement on the site, especially in the Forums, Blogs, and Course Notes sections. Looking forward to the much-needed improvement!!!
  4. Gain a competitive advantage with Wolfram Course Assistant Apps. Each app is custom designed specifically for today's popular courses. Wolfram Course Assistant Apps use an intuitive interface that guides you through the coursework to help you solve problems, not just give you the answers. As the makers of Mathematica and Wolfram|Alpha, we have been providing solutions in education for over 20 years. Now we're combining expert-level data, high-performance computation, and state-of-the-art interface design to give you the power to excel in all your classes—right in the palm of your hand.
  5. [ATTACH=CONFIG]79[/ATTACH] Light can control electrical properties of graphene ScienceDaily (2011-01-13) -- New research shows how light can be used to control the electrical properties of graphene, paving the way for graphene-based optoelectronic devices and highly sensitive sensors. ... > read full article
  6. FizziksGuy

    Feynman vs Lewin.

    Great point -- Richard Feynman did an amazing job of bringing complicated physics to the masses, and his lecture series is probably the most famous recording of an educational lecture in our history to date. Microsoft hosts 7 of the famous Feynman Lectures online at their Project Tuva site... check it out! To provide an idea of just how amazing he truly was, check out the first statement students heard in his introductory physics course at Caltech in the early 1960s. (PS, his lecture series was recorded and transcribed, along with pictures of his blackboard drawings, to create one of the most popular physics books of all time)
  7. Tremendous! I can't wait to talk my brother-in-law into demonstrating how it works on his Android phone! And also impressed by the QR codes... one of my "to-do" items includes integrating these codes with our course materials. Let us know what feedback you get!
  8. FizziksGuy

    Physics in general

    I don't think you're alone... so far you've always known what unit you've been working in, but now that we've covered a typical college semester at a high level, having things jumbled together isn't uncommon, especially after a long break. The good news -- we have one or two more days of material to cover, then we have a chance to sort everything out as we prepare for the mid-term. Take this time as an opportunity to clarify and organize your thoughts, to figure out your strengths and weaknesses -- then attack the weaknesses, and fortify the strengths. You know more than you think you do... our first WebAssign practice MC test is designed to be a tough one... an exam to help you realize where you need to work -- but not in a comfortable way. Use it as it was intended -- a tool to help you focus your efforts moving forward. And if it rattled you a bit, perhaps that's not a bad thing either -- but don't let it throw you from your course!
  9. FizziksGuy

    A Work In Progress

    Very, very cool! I am, yet again, impressed. Well done probablykevin!
  10. Hiya Grace... yup, got this one too. Just didn't get home until late last night. I'll make sure to up your Castle Learning score by 1 point. Have a great weekend!

  11. Amazing interactive flash demonstration: Scale of the Universe
  12. A great video on supersonic flight from AVweb!
  13. Great thermodynamics video!
  14. Pretty amazing -- and this will tie in very nicely with our upcoming study of springs and Hooke's Law!
  15. FizziksGuy

    Warp Drive

    No apologies required for String Guess... it's a very slick theory, and would be awfully nice if it were true -- just hard to call it a theory without any evidence! So many things yet to discover -- how many will we get to in our lifetimes?
  16. Very cool... now if only we could get the space program to undertake an ambitious goal and really push technology again!!!
  17. FizziksGuy

    castle learning

    I'm betting this is the problem to which you're referring... A 1.00-kilogram mass was dropped from rest from a height of 25.0 meters above Earth’s surface. The speed of the mass was determined at 5.0-meter intervals and recorded in the data table below. [ATTACH=CONFIG]72[/ATTACH] In this case, reading the velocity off the graph directly, I would estimate the speed of the mass as approximately 15.5 m/s (which Castle Learning should accept...) Unfortunately, it apparently only accepts 15.7 m/s as its exact answer. Your responses were 15 m/s and 15.5 m/s. As I can't adjust the assignment once it's been passed out, I will increase everyone's scores by 1 point on the assignment. Well done, and thanks for bringing this issue to light!
  18. FizziksGuy

    castle learning

    Can you give us more detail? Problem #? Cut and paste the problem here? Thanks!
  19. Sounds pretty cool to me! Was just talking to Mrs. FizziksGuy this evening and discussing the probability of Amazon developing a tablet PC based on Android to compete with the iPad in 2011... I think it's going to happen, she just rolled her eyes at me. :-)
  20. 10 and 11 are solved in similar fashions... start with conservation of energy: Then, of course, remember that: and You can find in your text that the radius of Earth is 6.37*10^6m, and with that information, each of those problems should become relatively straightforward. If you're still stuck, if you can post what you've done so far it will give us a better path to see what we can do to help!
  21. [ATTACH=CONFIG]68[/ATTACH] A colleague and friend of mine has offered a $20 Starbucks gift card to the student who can provide the simplest, clearest explanation of why the angular velocity and angular acceleration vectors point in the directions they do... check out the details and submit your entries in our Forums section! http://bit.ly/guQV0L
  22. [ATTACH=CONFIG]69[/ATTACH]My colleague has offered to "kick up" the challenge a notch. Details below: The prize: a $20 Starbucks gift card. The challenge: Provide the best step-by-step explanation (ala a geometric proof) using only concrete, physical descriptors; in other words, NO MATH equations, detailing why the angular velocity and angular acceleration vectors point along the axis of rotation. Your audience: students currently taking a full year AP C mechanics course. Half of them are currently in Calc BC; the rest are in AB. Only 10 of the 30 students took AP B last year; the rest took Physics 1 or no physics before this current AP C course. Winner will be determined by a class vote from our "audience." Please post challenge responses below... enter as often as you like, but remember to keep your audience in mind as you write your explanations!
  23. Hi All, I had a friend and colleague ask me today about why the angular velocity and angular acceleration vectors point in directions given by the right-hand-rule, as highlighted here... When I read my response, I realized that my answer wasn't much better than that given in the link... I thought about it some more and started thinking that it probably related to: and since the cross product of r and F is perpendicular to both r and F, with the positive direction given by RHR, the angular acceleration (and similarly angular velocity) vector must be consistent. Still not a very pleasing or clear explanation. So, why not turn to the experts? If someone were to ask you, how would you explain the direction of the angular velocity and angular acceleration vectors in a manner that was as clear and straightforward as possible?
  24. Hint for #3: volume of a sphere is: For this example, assume radius of planet is 4X Earth's radius... Start by finding mass of earth, which is density of earth * volume of earth: Mass of new planet must be: Using these two equations, solve for the mass of the planet as a function of the mass of Earth. Next, if you want the weight, or force of gravity, on this new planet: From here, you can substitute in for the mass of the planet and radius of the planet as a function of Earth's mass and radius to come up with a factor for the change in the force of gravity. As a final hint, for the case I provided (radius 4X larger), the force of gravity would be 4X greater. Good luck!
  25. Hint: Find the mass of the new planet relative to the mass of the earth (how many times more massive is it?) Next, find how much the radius changes compared to Earth. Then, substitute these values into Newton's Law of Universal Gravitation to find the weight on the new planet. If you can provide some background into what you're doing, I'd be happy to take a look and see where things are going awry...

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