Posts by Damon

Total # Posts: 32,299

  1. physics

    I think Scott is aiming you in the right direction F = G M m/r^2 potential energy = integral from infinity to r of F dr take it at 0 at infinity so it gets negative as you move in F dr = G M m int dr/r^2 = -G M m /r so as you move from Ro the surface to R, the increase is G M ...
  2. Math

    50 w > 250 so w > 50
  3. Math

    I guess, but your problem statement says nothing about the depth below the surface.
  4. Calculus

    Well, I did the indefinite integral and have no idea where your a and your square root come from. There is something your are not telling us.
  5. Calculus

    from where to where then and what is the a in (1/2)ax ? Please check what you typed carefully.
  6. Calculus

    integral of (cos (6x)+1) dx ??? from where to where or indefinite? anyway if you do not have a typo, that is the sum of two integrals cos 6x dx + 1 dx (1/6) sin 6x + x + c
  7. Math

    Or you could lay it out on a number line and notice that the 1/5 to 1/5 goes away :)
  8. Math

    May I say 2 - 1 + 1/5 - 1/5
  9. Science

    Yes, of course, positive buoyancy floats
  10. Huh?

    Hey, what do you think?
  11. Math

    Fringlebats cost $21 for 5 of them. How much will 12 of them cost?
  12. Math

    a+b+70 = 180 a+b = 110 max a = 70 so min b = 110-70 = 40 agree
  13. Math

    .023*68 = 1.564 yes + 68 = 69.6 ok agree A .135 * 68 = 8.97 NOT 9.18 disagree on C 8.97+68 = 76.97 NOT 81.5 disagree on D
  14. Math

    (.1812/12) * 529.84 = $12 It is 18.12 PER YEAR divide by 12 for month
  15. Math

    100* 2/7 = 28.6 % What on earth did you do?
  16. math plz help! urgent!

    So I did your wave equation below Waves
  17. Physics

    The equation is: d^2y/dx^2 = (1/c^2 )[d^2y/dt^2] here: d^2x/dz^2 = (1/c^2 )[d^2x/dt^2] with the strange letters for displacements I will just do the half that is moving right (z+ct)= constant or f(z-ct) write as f(w) where w = z-ct df/dz = df/dw * dw/dz = df/dw d^2f/dz^2 = d^...
  18. Physics

    Oh my, I have to get my old MIT T shirt out of the closet? well, the amount of E coming out is proportional to charge inside for example. That is one of them. It can be expressed in integral or in differential form. In integral for example: integral over closed surface of E ...
  19. Physics

    You are evidently working in feet and inches assuming this event occurred on earth. s is the height above the launch point here. 80 ft/s is initial speed up and 16 is g/2 s = 80 t - 16 t^2 the velocity upward is the time derivative of height v = 80 - 32 t at t = 2, v = 80 - 64...
  20. fluid mechanics

    work done per second = rho Q g h = useful power you need more for head losses rho Q g (h+22) = power needed , Q is in m^3/s = 850,000 * 0.78 rho = 1000 kg/m^3 g = 9.81 m/s^2 so 1000 * Q * 9.81 (64) = 0.78 * 850,000
  21. MATH!

    half of 18% of 100 :)
  22. MATH HELP!!!!!!

    To get from a fraction to a percent multiply by 100
  23. Math

    What you want to use is (a-b)(a+b) = a^2-b^2 and you do not want square roots in the denominator so multiply top and bottom by (1+?3) and you will have 1-3 = -2 in the denominator
  24. Physics

    The total angular momentum stays the same, but the bug pushes back on the disk to move forward on it.
  25. Physics

    Yes.
  26. Geometry

    right 8 and up 4 magnitude = sqrt (64+16)= sqrt (4^2* 4 + 4^2) = 4 sqrt 5= 8.9 tan angle n of e = 1/2 so angle n of e = 26.6
  27. Algebra

    x + y = 5 x - y = 2 ======================= Substitution solve the top one for x or y eg y = 5 - x substitute that (5-x) for y in the second one x - (5-x) = 2 2 x -5 = 2 2 x = 7 x = 3.5 then y = (5-x) = 1.5 ======================================== elimination get magnitude of ...
  28. Math

    both start at origin Ship one 110 from north is 20 degrees below +x axis x1 = 2 * 32 * cos 20 y1 = -2 * 32 * sin 20 Ship 2 230 from north is 40 deg below -x axis x2 = -2 * 40 cos 40 y2 = -2 * 40 sin 40 d = sqrt [(x2-x1)^2 + (y2-y1)^2 ]
  29. Physics

    I interpreted as rise during push, not total height
  30. Physics

    A. (1/2) m v^2 = 2.7*10^-4 J (1/2) (2.3*10^-4) v^2 = 2.7*10^-4 v = 1.53 m/s agreed B. Work done = force * distance 2.7*10^-4 = 0.44 d solve for d
  31. Math

    https://www.mathsisfun.com/geometry/herons-formula.html
  32. Math

    length and width decreased by 0.80 * 2 = 1.6 m L = w = sqrt 72.25 = 8.5 m A = (8.5 -1.6)^2
  33. science

    9.8 * Re^2/Rn^2 * Mn/Me = 9.8 *1/3.89^2 * 16.7 = 10.8
  34. Physics

    2*10^-6 Coulombs/second pass a point on the wire every second 1 electron is 1.6*10^-19 Coulombs so 2*10^-6 Coulombs/second * 1 electron/1.6*10^-19 Coulombs = 1.25*10^13 electrons/second electrons/s = electrons/cm^3 * area*velocity = what is electrons/cm^3? density = 8900*10^3 ...
  35. Physics,,,,,,,How do I solve this?

    Lower frequency ---> longer wavelength because T = 1/f = distance/speed then for part B we know the frequency of red is lower. The frequency and period DO NOT CHANGE (there is no place to store extra waves) Therefore if the wavelength of red gets shorter it had to cover ...
  36. Chemistry

    This might help. See page 4. http://fileserver.net-texts.com/asset.aspx?dl=no&id=5630
  37. american government

    I am not going to disagree with you. I think a case can be made for A and for D.
  38. american government

    Yes, that is one case where my theory fails. However usually I think the third party candidate is more in the nature of Ross Perot.
  39. american government

    I am inclined to agree with you. However if I had to choose one I think I would pick A. More often than not a third party candidate takes votes from the candidate who is NOT dominant. The third party candidate and the main stream challenger split the votes cast against the ...
  40. american government

    I would pick B because it is not modern at all and I do not think it is even used seriously any more.
  41. Math

    Looking at your other question I wonder if you typed this one incorrectly as well. Could you perhaps have meant that there were 7 females for 8 males? That would be more common. In that case 7/15 are female 100(7/15) = 46.7 %
  42. Math

    (7/8)48 = 7*6 = 42 are female 100 (42/48) = 87.5 %
  43. You try first

    What are your answers?
  44. Physics

    F = d momentum/dt = mass/second * v so F = 60 kg/s * v = m g = (1000+3000) (9.81) so v = 4000*9.81 / 60
  45. Physics

    a m/s^2 b m/s c m If an object is acted upon only by acceleration a then x = Xi + Vi t + (1/2) a t^2 Xi is initial position in meters Vi is initial velocity in x direction in meters/second a is acceleration in x direction in meters/second^2
  46. Algebra

    area of square outside frame = x^2 area of painting inside frame = (x-2)^2 so x^2 - (x^2 -4 x + 4) = 4 x -4
  47. Algebr

    You are welcome.
  48. Algebr

    5d(3d^2+8d-3) + 2 (3d^2+8d-3) ------------- add and simplify 15d^3 +40 d^2 - 15 d + 6 d^2 + 16 d -6 ------------------ 15d^3 + 46 d^2 + 1 d - 6
  49. Lab Physic

    I guess you mean a pendulum (Please type entire problem in the future) let theta = A sin 2pi t/T h = L (1 - cos theta) for small theta that is h = L theta^2/2 h max = (L/2)A^2 Max potential energy = m g h max = m g (L/2)A^2 theta= A sin 2 pi t/T v = A L (2 pi/T) cos 2 pi t/T ...
  50. science

    Displacement is position vector in this case it is 70 i + 100 j in x y coordinates where i is unit x and j is unit y vectors its magnitude is sqrt (70^2 + 100^2) it direction north of east is tan theta = 100/70 the compass angle east of north is 90 -theta
  51. math

    2 pi * (6) = circumference so (35/60)(2 pi)(6)
  52. You try first

    enough
  53. physics/electrical circuits

    Hey, look, I do not need practice. You do. Post your attempts.
  54. Chemistry

    1 mole of C8H18 ---> 8 mols of CO2 mol mass of C8H18 = 2*12 + 18 = 42 g/mol so (34.6/42) mol of C8H18 so 8(34.6/42) mol of CO2 mol mass of CO2 = 12 + 2*16 = 44 g/mol so in the end 44 * 8 (34.6/42) grams of CO2
  55. physics/electrical circuits

    i = V/total R = 11*V/R so R/11
  56. enough already

    Hey, enough. I answered these.
  57. physics/electrical circuits

    i = V/2R P1 = Vi =V^2/2R after new Rn = R/2 i = V/(R/2) = 2V/R P2 = Vi =2V^2/R P2/P1 = 4 so if P1 = 20 P2 = 80
  58. physics/electrical circuits

    resistance proportional to length and inversely to area 4/2 =
  59. physics/electrical circuits

    if diameter is twice resistance is 1/4
  60. Math

    wins = 7 x losses = 2 x total games = 9 x so 9 x = 27 x = 3 wins = 7*3 losses = 2*3
  61. Math

    3 C = 3(2 pi r) = 66*10^3 meters so r = (11/pi)10^3 meters
  62. math;)

    sec x = 1/cos x cos is between -1 and +1 when x = pi/2 or 3pi/2 the denominator is zero, boom so it has no zeros cos is symmetric about origin, so this is as well
  63. Science

    I would lower the baseball so it was completely under water into a pan of water filled to the brim and then measure the volume of water that spilled over with a measuring cup.
  64. Math

    You are welcome.
  65. Math

    8 - 3 |x| = 2 - 3 |x| = -6 |x| = 2 x = + 2 or x = -2 so p-4 = 2 so p = 6 p-4 = -2 so p = 2 I agree with you.
  66. math

    You are welcome. But PLEASE learn to add angles to 180 in a triangle. Promise ?
  67. math

    1. Hey 180 - 68 - 22 = 90 ! 2. Same mistake 71 + 71 + 38 = 180 It already said it was an isosceles triangle because two equal sides ! 3. Once again 45 + 90 + ? = 180 and you know two angles have to be equal !! 4. OF COURSE the angles of an equilateral triangle are congruent ! ...
  68. Physics

    F =-k x -m g = -k x (0.030)(9.81) = k (0.05) k = (0.030)(9.81)/(0.05) Newtons/meter
  69. error

    6/7 = 24*6/168 = 144/168 so it should be (21+144+28)/168
  70. math

    just like 2 pumpkins + 3 pumpkins = 5 pumpkins 2(1/6) + 3(1/6) = 5/6 but 2 apples + 3 pumpkins is just that :) 1(1/3) + 1 (1/2) = nothing useful but that
  71. math

    Annabelle, To add fractions you need a common denominator. like 1/3 + 1/2 = 2/6 +3/6 = 5/6
  72. math

    Annabelle -- no!
  73. math

    8 = 2*2*2 7 = 7 6 = 2*3 so least common multiple is 8*7*3 = 168 1/8 = 21/168 6/7 = 24/168 1/6 = 28/168 so (21+24+28)/168
  74. Physics

    I am not sure I understand but maybe something like this? let z = 1/r^2 F = G M1 M2 z dF/dz = G M1 M2 = 70 ? G = 6.67*10-11 m^3 kg^-1 s^-2 dF/dz = 6.67*10^-11 M1 M2 = 70 M2 M2 = (70/6.67)10^11
  75. Math

    In other words you can do it the math way with proportions or the science way with units.
  76. Math

    486 blueberries (15 min/135 blueberries) = (486/135)*15 min = 54 min
  77. Science

    But it was elastic so B has to go right after V = -30 before A moving right at 30 after A moving left at 30 before B moving left at 10 after B moving right at 10 speeds of both the same before and after so same Ke momentum is zero before and after
  78. History

    Clearly written by a Mexican. It was not only lamentable for his country(Mexico) but also for the reputation of the Americans. Even Americans thought it was robbery etc, etc, etc
  79. Math

    well if six students each get half a roll, you better start with three rolls :)
  80. Physics

    Well, completely elastic is impossible of course but a Newton's cradle is very, very close. https://www.youtube.com/watch?v=eUSTw8nLfZM Inelastic is easy, any two cars that meet, crash, and stick to each other as they slide away.
  81. Social Studies

    ..in a cavern, in a canyon, excavating for a mine .... Where do you suspect? I have a hunch they came from a lot of places, but only a few from China and those mostly to build railroads to the gold. People from here (East Coast fishing port) went there looking for gold. (but ...
  82. Physics

    first geometry 3,4,5 triangle sin A = 0.6 so A = 36.9 degrees slope cos A = 0.8 now problem normal force = m g cos A = .8 m g friction force = mu m g cos A = mu(.8m g) force down slope = m g sin A = .6 m g begins to slide so forces equal and opposite .8 mu m g = . 6 m g mu = 3...
  83. physic

    :)
  84. physic

    No problem, was able to get there from first link.
  85. physic

    Say TL = tension in left string Say TR = tension in right string a = acceleration of all to right On the middle mass F = TR - TL - 0.10*2*g = 2 a TR = 5.06 (g-a) TL = 4.24 (g+a) so 5.06(g-a)-4.24(g+a) =2 a + 0.2g 0.82 g - 9.3 a = 2 a + 0.2 g 11.3 a = 0.62 g a = .055 g if g = 9...
  86. Physics and nobody knows

    If you pasted a diagram, that does not work here.
  87. algebra and a little bit of geometry

    well, on the left you have a four sided figure with parallel vertical left and right sides. The height on the left is 5 and on the right it is 6 so the average height is 5.5 and the base is 4 so that left partt has area = 4 * 5.5 = 22 then on the right you have an isoseles ...
  88. Math / geometery

    sqrt(144+49)
  89. Math

    Well, for fun: 6*4 = 24 so 24 yards + 4 yards + 2 feet + 6 in 24 yards + 14 feet + 6 in 24 yards + 12 feet + 2 feet + 6 in 24 yards + 12 feet + 30 in now divide by 6 :) 4 yards+ 2 feet + 5 in or in inches 1038/6 =173 inches (Which comes out the same luckily :)
  90. Math

    I did the other one. You do this one.
  91. Math

    A = 1.6 p B = .4 p B/A = .4/1.6 = .25 25%
  92. social studies

    Agree, read Hemingway "For Whom the Bell Tolls".
  93. physics

    I guess by falling it means tangential velocity F = ma = mv^2/r where m is mass of body n orbit = G m M/r^2 where M is mass of central body, in this case earth so v^2 = GM /r call moon orbit r = 1 and sun r = 372 so for moon 1.4^2 = G M/1 and sun v^2 = G M/372 v^2 = 1.42^2/372...
  94. Math

    Nice answer !
  95. Math

    LOL -infinity and (infinity+10)
  96. Math

    I assume all positive 0 and 10 0 if that is not allowed 1 and 10
  97. math

    divide by 9 which is 3 squared like length/3 * width/3 but in general for similar figures area is proportional to length squared and volume to length cubed
  98. Ap chemistry

    half hour = 30 min = 3 half lives 84 * 1/2 * 1/2 * 1/2 = 84/8 = 10.5g or in general mass = original mass /2^n where n is the number of half lives
  99. algebra

    V = pi r^2 * h 224 pi = pi (16) h h = 224/16
  100. Math

    cos 8t = 3 sin 8 t tan 8t = sin 8t/cos 8t = .333333333333333 8 t = 18.4 degrees t = 2.3 in degrees t = 2.3 *pi/180 = .04014 seconds if you do trig in radians =================== check t = .04014 8 t = .321 radians or 18.4 deg cos 18.4 = .949 3 sin 18.4 = .947 pretty close
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