Recent content by awvvu

  1. A

    Getting time domain current from impedance and voltage measurement?

    Yeah, but I can only measure the input current into the switcher, and that's not useful for getting transient data. The actual load is a BGA chip so I can't use a current probe directly.
  2. A

    Getting time domain current from impedance and voltage measurement?

    Can't do that, the power supply is 1V and the load is almost 100A. The power trace is an entire internal plane to minimize I^2 R loss, so I think the only way to measure the current is indirectly.
  3. A

    Getting time domain current from impedance and voltage measurement?

    I'm working on a high power multi-phase DC/DC converter where the load current has some fast transients. We can easily measure the output voltage in the time domain, and also measure the power distribution network impedance in the frequency domain. So, I think I would try converting the...
  4. A

    Comparing Stewart's Calculus 6e & Essential Calculus - A Guide

    The description on Amazon sums it up pretty well: https://www.amazon.com/dp/0495014281/?tag=pfamazon01-20
  5. A

    Fundamentals of Physics Extended, 8th Edition

    I used this textbook for AP Physics Mechanics and E&M in high school and I thought it was pretty well-written.
  6. A

    Need help on approach to physics education

    We used the book for our AP Physics C class and I really liked it. The workbooks began to get tedious to do though.
  7. A

    How can you multiply two negative numbers?

    How about this: A particle is moving left at a speed of 5 on a number line (so its velocity is -5). It starts at the origin at t = 0 s. Where is the particle at t = -2 s? x = v * t = -5 * -2 = 10. So, 2 seconds before it's at the origin at t = 0, it is 10 to the right at t = -2.
  8. A

    Testing Deciding Between the ACT and SAT: What's the Difference?

    Yeah I did really well on the math and reading sections but only got a 670 on the writing. It's not counted as much anyway. I took it twice, with a year in between and improved a lot. I did a lot of practice tests to prepare. I did sign up for the ACT too, but decided not to take it after...
  9. A

    Introducing the PF Library

    Haven't seen any response to this, but I second it. blah blah angular momentum blah blah.
  10. A

    Testing Deciding Between the ACT and SAT: What's the Difference?

    My school (in Maryland) has this college tracking program that plots accepted people's SAT and GPA scores on a graph. Most of our graduating seniors go to UMD CP, so this should be helpful for you: http://img518.imageshack.us/img518/4966/genscattergramphppo5.png...
  11. A

    Review of 2008 AP Physics C E&M Free Response | Student's Perspective

    Do you know Gauss's law? Between the two spheres, there is still a net charge enclosed so therefore there's an electric field. It's only zero inside the conductors.
  12. A

    Review of 2008 AP Physics C E&M Free Response | Student's Perspective

    The positive inner sphere polarizes the outer sphere, pulling negative charges to the inner surface, and leaving positive charges on the outer surface.
  13. A

    Review of 2008 AP Physics C E&M Free Response | Student's Perspective

    Yeah I screwed up my graph on the test. Drew a linearly downsloping line and made it zero after it hit the axis. Terminal velocity is never actually achieved, acceleration actually never hits zero, only in the limit as time goes to infinity. They want acceleration as a function of time, not as...
  14. A

    Review of 2008 AP Physics C E&M Free Response | Student's Perspective

    Continuing, forum downtime made me miss the edit window. #3: Part c is definitely a conservation of energy problem. At the top, it has mgh potential energy, and at the lowest point, it has maximum spring potential energy and zero gravitational potential energy. Both points have no kinetic...
  15. A

    Review of 2008 AP Physics C E&M Free Response | Student's Perspective

    For reference, here are the original problems: http://apcentral.collegeboard.com/apc/public/repository/ap08_physics_c_mech_frq.pdf Drag force goes back up the slope. The force equation is really a vector equation, \vec{F} = -b \vec{v}. v is down the slope, so F must point exactly up the slope...
Back
Top