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  1. O

    Oxidation states

    The book I'm reading, has suggested to methods for assigninig the oxidation statetes in a compound. The first method includes drawing the Lwis structure of the compound. And the second one is based on some rules. As I'm a beginner in chemsitry there are so many compounds which I can't draw...
  2. O

    Equation of a plane

    You're right. The problem was with the scales. I used to work only with 2D curves and I don't know how long it will take to get used to these 3D surfaces. Now, may I ask you how the problem can be solved? When I write the conditions of the required plane, I find a system with 4 unkowns and...
  3. O

    Equation of a plane

    So what about the graph? I used Maple to draw both the planes in 3D and, as I told you, the angle between the two planes is less than 90 degrees. Am I missing something?
  4. O

    Equation of a plane

    Here is the problem I need help with: Find the page perpedicular to the plane x+3y-z-7=0 and containing the points (2,0,5) and (0,2,-1). The answer given in the book is 2x-y-z+1=0. But when I plotted x+3y-z-7=0 and 2x-y-z+1=0, by a PC runnig Maple, they don't look perpendicular to each...
  5. O

    How many odd numbers are there between 3000 and 7000

    Sorry but, what do you mean "by brute force"?
  6. O

    How many odd numbers are there between 3000 and 7000

    The book is wrong then. Thank you very much.
  7. O

    How many odd numbers are there between 3000 and 7000

    Lack of enough IQ :D Sorry but I don't get it :cry:
  8. O

    How many odd numbers are there between 3000 and 7000

    1008? Your solution looks eager and completely new to me. But the answer in the book is this: 4 X 8 X 7 X 5 = 1120. First let me clear it up: How many odd numbers with distinc digits are there between 3000 and 7000? Distinc means a number like 3011 is not valid because 1 is used two...
  9. O

    How many odd numbers are there between 3000 and 7000

    How many odd numbers are there between 3000 and 7000, NO REPEAT? My answer is 1232 which is wrong according to the solutions manual.
  10. O

    Bohr's atomic model

    Thank you
  11. O

    Bohr's atomic model

    Surely I have done the reading, these are the quetions of that chapter. I don't get what happend to the classical physics principle, the one that said: a charged mass radiates when it accelerates. Did Bohr model reject that principle? Or we still believe in it? P.S I'm studing chemistry :)
  12. O

    Bohr's atomic model

    I need help with these 3 questions: 1. Describe the Bohr model of the atom. How does it differ from a planetary model based on classical physics? ======================== 2. In terms of the Bohr theory why is that electrons don't spiral into the nucleus? ======================== 3. If...
  13. O

    Permutation and Combination

    The third one please.
  14. O

    Permutation and Combination

    Ok, so I must start posting jillions of problems to this forum; to get help from experts. Thank you.
  15. O

    Where does the energy come from?

    Thank you very much.
  16. O

    Permutation and Combination

    Consider these problems: 1. In how many ways can 7 boys be seated around a round table? 2. If seven beads of different colors are put on a ring how many different desighns can be made? 3. I have six books with identical black bindings, 8 with identical red bindings. In how many ways can I...
  17. O

    Where does the energy come from?

    When a helium balloon soars into the sky, it gains KE and gravitational PE. where does that energy come from?
  18. O

    The gravitational force between the aircraft and Moon

    Here is a problem, please let me know whether my answer is right or wrong. Locate the position of a spaceship on the Earth-Moon center line such that the tug of each celestial body exerts on it would cancel and the craft would literally be weightless. I found two equations: A...
  19. O

    Find f(x)

    Tell me how was I soppused to carry out? Check it out: >If : >f( (x-1)/(x+1)) + f(-1/x) + f( (x+1)/(1-x)) = x >Find f(x) without using derivatives nor limits nor Integrals. Cute. Left side is not defined for x = -1, 0 or 1, but I guess we should ignore that. Let h(x) = (x-1)/(x+1), and...
  20. O

    Find f(x)

    I don't know wether it's right or wrong. Anyway, can you tell me how did you get it?
  21. O

    Find f(x)

    I plugged in so many xs but I just don't get it. Consider that this problem must be solved in 2 or 3 minutes in the exam. Anyway thanks for your help Hurkyl.
  22. O

    Find f(x)

    Let's do it now. x = 2 : f(1/3) + f( -1/2) + f (-1/3) = 2. Now what does it mean? I see a pattern but... I can't find f(x) anyway. Can you give me some hints?
  23. O

    Find f(x)

    If : f( [x-1]/[x+1]) + f(-1/x) + f( [x+1]/[1-x]) = x Find f(x) without using derivatives nor limits nor Integrals. Thanks
  24. O

    Two cars, one accelerating and one

    I don't know, what made me think that problem is a "new and unknown " problem. Maybe some mistakes in calculations and some misleading hints in the solutions manual. Ok, thank you very much for clearing things up. For now let me bring another " new and unknown " problem :)) A motorcycle...
  25. O

    Two cars, one accelerating and one

    I didn't, the answer was in teh solutions manual :biggrin:
  26. O

    Two cars, one accelerating and one

    But I already had the answer, what I need is some explanations to understand the problem; NOT just a formula. I don't really get it. Why do we use their relative speed? Why do we look at it from the perspective of the Cadillac. I have 5 problems all the same type, A moving at a constant speed...
  27. O

    Two cars, one accelerating and one

    The driver of a pink Cadillac traveling at a constant 60 mi/h is being chased by the law. The police car is 20 m behind the perpetrator when it too reaches 60 mi/h, and at that moment the officer floors the gas pedal. If her car roars up to the rear of the Caddilac 2.0 s later, what was her...
  28. O

    Will they collide? No but

    Thank you Ok. What if two accelerations were equal ? Thank you
  29. O

    Dragster average acceleration

    I'm reading physics on my own, there is no teacher to check with. PF is the only place to ask my questions. Thank you very much amwbonfire and HallsofIvy
  30. O

    Kinematics (3 in 1)

    Yet there are 2 questions for me. 1. The formula for t_y ( problem 38 ) is not INDEPENDENT of S_s as the problem asks to be (our formula is : (v_i) (0.6 s) + [((v_i)^2) / 2a ] + S_i which is equivalently (v_i) (0.6 s) + [ S_s ] + S_i ). 2. Which of the several contributing aspects requires...
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