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Homework Help: How many "C" does it take to balance one "A"?

  1. Jun 21, 2008 #1
    How many "C" does it take to balance one "A"?

    A A A A A B B B B A C C
    ------------- ------------ -------- ---------
    l l l l
    __________________ ____________
    * *
    Last edited by a moderator: Jun 21, 2008
  2. jcsd
  3. Jun 21, 2008 #2

    Doc Al

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    Staff: Mentor

    Give us a hint: What are you talking about? Is this a physics question? What do the letters represent?
  4. Jun 21, 2008 #3


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    I tried to make the picture look better, but I can't get it to work. If you hit quote (or edit) on his post, then you can see what he means.

    Doesn't look like a physics question to me though, probably more like a precalc math question.

    MarianKh; can you write an equation for each balance?
  5. Jun 21, 2008 #4


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    Thanks for suggesting "quote", Cristo.

    In other words, 5 "A"s is equivalent to (balances) 3 "B"s and 1 "B" is equivalent to 1 "A" and 2 "C"s. How many "C"s is 1 "A" equivalent to?

    Since MarianKh showed no attempt to work this and has not responded to questions, I see no reason to continue.
  6. Jun 21, 2008 #5

    im facin a problem in writing the equation its like a balance ill draw it at paint and attach it here
  7. Jun 21, 2008 #6


    Attached Files:

    • FZX.bmp
      File size:
      221.1 KB
  8. Jun 21, 2008 #7

    Doc Al

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    Write each balance as an equation. You'll have two equations. Solve by eliminating B so you have A in terms of C.
  9. Jun 21, 2008 #8
    Thank you ver much for helping me through this still i have 4 questions but i don't want to bother...
  10. Jun 21, 2008 #9
    Please Help Me Solve Those 5 Equations

    im unable to pose another thread so im writing on this one. Please help me solve those four equations

    An 8.0-meter long ladder leans up against a wall with the bottom end of the ladder resting on the ground 1.0 meter from
    the wall.
    a. How high off the ground is the upper end of the ladder?
    b. What angle does the ladder make with the ground?

    Question 2:
    For the following situation, draw a diagram that shows what is being explained below. (No calculations are needed –
    just a drawing!) In a movie theater one day, Alex spends some time trying to figure out which row gives him the best
    view of the screen. Since people determine relative size of an object by the subtended angle (or the angle formed from
    the top of the object to the eye to the bottom of the object.), Alex is looking for the location with the largest subtended
    angle. The screen is 18 ft. tall, and its bottom edge is 6 ft. above eye level. Sitting 36 ft. from the plane of the screen is
    not satisfactory, for the screen is far away and only subtends a 24.2° angle, while sitting 4 feet from the screen is just as
    bad, because the screen subtends the same angle.

    Question 3:
    Find the next number in the following sequence: (Justify your answer.)
    108, 72, 48, 32, ???

    Question 4:
    A softball pitcher throws a ball straight up by mistake. The height of the ball (in meters) off the ground as a function of
    time (in seconds) is given by the following equation:
    H = 22t - 4.9t2
    When is the ball at a height of 15 meters above the ground?

    Question 5:
    is found in the attachment.

    Attached Files:

  11. Jun 21, 2008 #10
    You have to show your work on this forum. We don't just give you answers. You have to put in some effort before we help.

    I'll start you off with question 1. Draw a picture from there it should be obvious how to get the height.
  12. Jun 21, 2008 #11
    thank you for motivation me :)
    is the answer of a. 7.9?
    is the answer of b. 82?
  13. Jun 21, 2008 #12
    That's correct but I think you rounded down for b. I got 83. Care to tackle the rest of the questions by yourself and if you have difficulty you can always come back to the forum.
  14. Jun 22, 2008 #13
    I solved question 3 and four
    is the answer of the third question 21.3?
    is the answer of the foruth question either 15, and 7.55?

    but im having diffuclty in both question 2 and 5! can you please help
  15. Jun 22, 2008 #14
    It would help if you could show the work to how you got the answers instead of just posting what you got.

    The second question is slighty difficult in the understanding. Try sketching it various times and see what you come up with. You might be a little confused about subtended angle. Draw a triangle from Alex's eye to the screen. The angle across the screen where alex's eye is would be the subtended angle.

    Edit: As for question 5, graph the points you have and determine the shape the graph will take. You can also use the graph to estimate the Y value.
    Last edited: Jun 22, 2008
  16. Jun 22, 2008 #15
    Many thanks.

    please excuse but english is not my native language i fin some diffuclty in undeerstanding english equations.

    Question 1:
    a) 1(squared) + x(squared) = 8(squared)
    1+x(squared)= 64
    x(squared) = under the rood 63
    x= 7.9

    b) cos the angle= 1/8
    by using the calculator the angle will be 82.8

    Question 3:
    108/72= 1.5
    72/48= 1.5
    48/32= 1.5
    so all the answers are 1.5
    so we sibstitute:
    32/x= 1.5
    y= 21.3

    Question 4:
    15= 22t-4.9t(squared)
    15= t(22-4.9t)
    in case one: t=15
    in case two:
    15= 22-4.9t
    after removing 22 from the right we remove them from the left

    i drew a triangle and the subtended angle will be from Alex's position but i couldnt solve it!
    please i need ur help here...
  17. Jun 22, 2008 #16
    Their is no solution for question 2. You need to only draw 2 pictures. The first one you already drew. You just need to add the bottom ledge and the 36 foot distance from the screen. It would help if you could somehow put your triangle on the forum.
  18. Jun 24, 2008 #17
    Thank you for helping me in this question.
    could you please help me in the fifth question
  19. Jun 25, 2008 #18
    For question 5 plot the points on a graph to help you see what the shape of it will be and what the equation of the graph can be.
  20. Jun 25, 2008 #19
    wut is larger 6.672 or 6.67?
  21. Jun 25, 2008 #20
    6.672 is greater than 6.67. If the number of digits confuses you just add a zero to 6.67. So you can compare 6.672 to 6.670 if you are having difficulty.
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