Posts by Damon

Total # Posts: 32,928

  1. Math

    400.00 - 57.38 - 33.50 + 20.00 = ???
  2. physics

    speed = 3 * 10^8 m/s / 1.5 = 2*10^8 m/s distance = 0.9 meters (really ? ) time = (0.9 /2) * 10^-8 seconds
  3. Calc

    What second line? What first line? That is a parabola. Its slope is df(x)/dx = 2x - 12
  4. Calc!

    distance / time for example from time 0 to 1.5 (66-0) / (1.5-0) = 44
  5. math;)

    Hey, you try first. You are supposed to know how to take the derivative of a polynomial. if y = a x^n then dy/dx = n a x^(n-1) and the derivative of a constant is therefore 0 because if y = a x^0 dy/dx = a * 0 * x^-1 = 0 so if v = -t^2+15 then a = dv/dt = -2 t + 0 and at t = 5...
  6. math;)

    f'(x) = -2x at x = 1 f'(x) = slope m = -2 so y = -2x + b at (1,4) 4 = -2 + b b = 6 continue f' = 8 x + 2 so put in a for x what is your problem with this?
  7. math;)

    f' = 12 x - 1 so what is -12 - 1 ?????
  8. science

    1 S + 1 N = 0 5 W = 5 W We are interested in his motion vector, not where he started so in the end his displacement vector was 5 W
  9. Calc

    It would have made much more sense to ask you what is average velocity from t = t to t = t+h ? s(t+h) = 15 + 31 (t+h) -4.9 (t^2+2 t h+h^2) s(t) = 15 + 31 t - 4.9 t^2 then distance moved is s(t+h) - s(t) = 31 h - 9.8 t h - 4.9 h^2 divide by time elapsed h [ s(t+h)-s(t) ]/h = 31...
  10. Calc

    at 0 it is 15 at (1+h) it is 15 + 31(1+h) - 4.9(1+h)^2 subtract d moved = 31(1+h) - 4.9(1+h)^2 divide by time (1+h) d moved/time = 31 - 4.9(1+h)
  11. Calc

    if I go 4 miles from here to downtown at 30 miles/hour, then immediately come back at 30, my average velocity is ZERO. I went nowhere :) However my average SPEED was 30
  12. Calc

    The reason I went into that detail is I am not sure your question is worded correctly. I wonder if they really want the average speed, not the average velocity.
  13. Calc

    average velocity = displacement / time by the way NOT distance/time distance is scalar displacement is vector, might be - part of the time. if on earth and original height = 15 meters original speed up = 31 m/s and v = 31 - 9.8 t acceleration = -g = -9.8 m/s^2 then h(t) = 15...
  14. chemistry

    P V = nRT here V, n and R are constant so P/T = constant so P1/T1 = P2/T2 So I agree with you.
  15. Science

    Yes
  16. Electron acceleration

    Yes m a = q E so E = m a/q
  17. math:^]

    work = Force * distance in direction of force = Force vector dot Distance vector = |F| |D| cos angle between the two vectors = 60 * 100 * sqrt 2 / 2
  18. science

    You can assume for this problem that the speed of light is infinite, about 3*10^8 meters/second which is a lot bigger than 346. so in the two seconds between the flash and the noise the sound traveled 2*346 meters
  19. Sue

    60/21.5 = h/19
  20. Orbital period

    http://www.physicsclassroom.com/class/circles/Lesson-4/Mathematics-of-Satellite-Motion T^2/R^3 = constant for any old star
  21. physics

    when she crosses the bar she is moving in horizontal direction Ux = 1.16 the whole time. Now the vertical problem: (1/2) m Vi^2 = m g h so Vi = sqrt (2gh) {This is worth remembering} Vi = sqrt (2*9.81*1.89) = 6.09 so |v| = sqrt (1.16^2+6.09^2) = 6.20 sure enough
  22. math

    You do not tell us what the question is but I could not do it anyway because I do not know if the 3 were caught in the first minute or the fourth or whatever.
  23. Maths

    (1/3) long , x = (3/4) short , y x = y + 17.5 (y+17.5)/3 = 3 y/4 4 y + 70 = 9 y 5 y = 70 y = 14
  24. math

    Five of the eight letters are not e.
  25. Physics

    watts = volts * amps
  26. Math

    3(22+20) = 3(42)
  27. Social studies

    I agree.
  28. Math

    3x+2 = x^2+3x-4 x^2 - 6 = 0 x = +/- sqrt 6 if +sqrt 6 y = 3sqrt 6 + 2 = 6+3sqrt 6 -4 check :) there are solutions but none of them are on your list
  29. History

    I do not think it is C.
  30. math

    https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
  31. math

    arithmetic sequence, a = 14, d = 5
  32. math

    Yes
  33. Math

    20 = 4 * 5
  34. Computer

    https://www.binaryhexconverter.com/binary-to-decimal-converter You want decimal? 2824088250
  35. physics

    original momentum = .050 * 0.6 + 0 = 0.03 final =0.03 = 0.050* 0.24 + 0.20* v solve for v
  36. science

    gain of of kinetic energy at low spot = loss of potential energy coming down from top (m/2)(Vbottom^2 - Vtop^2) = m g (meters down from top) or if stopped at top (1/2)m v^2 = m g h or (remember this) v = sqrt (2 g h)
  37. Calculus

    You did not say how many rectangles. Here it is for ten: http://mathworld.wolfram.com/RiemannSum.html
  38. Calculus

    graph it! You know how to find the area of rectangles and triangles.
  39. Chemistry

    I would have .62 mols in a liter so I have .62 (.032 ) = .01984 mols .01984 mols /x liters = 0.3 mols/1 liter x = .01984/.3 = .06613 liters = 66.13 mL so add 66 -32 = 34 mL of water
  40. Math

    14! = 87?178?291?200 indeed
  41. Geometry

    It was unclear to me which way the scale was supposed to go actually.
  42. Geometry

    if the scale factor is s Like L' = s L and w' = s w and h' = s h then L'w' h' = s^3 L w h in other words volume scales as the cube of the length scale if the volume of one thing is twice another similar object then every length measure on the big one is...
  43. Chemistry

    Yes, I should have said that :)
  44. Chemistry

    there are 3 times as many Na+ ions as sodium phosphate molecules 3.3*3 = 9.9
  45. Math

    Exactly Michael.
  46. physics

    work done = F D = gain in Ke Now which of those has the same force times distance (time has nothing to do with it)? We are not doing power, just energy.) The heavier mass will just end up moving slower if they started at rest but will have the same gain in Ke.
  47. Science

    work output = 30*2 = 60 Joules work input effort = 10*8 = 80 Joules well the time is the same so the velocity out is 2/8 = 1/4 the velocity in eff = 100 * work out/work in = 100(6/8) = 75%
  48. Algebra

    four times a year so every 1/4 year multiply by 1 + .075/4 = 1.01875 do that for n years or in other words 4n periods so 3 = (1.01875)^4n log 3 = 4n log 1.01875 I suspect you can take it from there.
  49. History

    You just want me to answer the questions for you? Read the excerpts carefully and try to answer before asking us to do your reading for you please.
  50. vectors

    Somehow you can tell one of us does physics and the other does math :)
  51. vectors

    x = a i + b j y = c i + d j a^2 + b^2 = 11^2 = 121 c^2 + d^2 = 23^2 = 529 x-y = (a-c)i + (b-d)j (a-c)^2 + (b-d)^2 = 30^2 = 900 = a^2 - 2ac + c^2 + b^2 -2bd + d^2 so 900 = 121+529 -2(ac+bd) so 250 = -2(ac+bd) now x+y = (a+c)i + (b+d)j |x+y|^2 = a^2+2ac +c^2 +b^2+2bd+d^2 = 121+...
  52. vectors

    I put A at lower left and B a lower right. AB = 1 i + 0 j AC = (1+cos 60)i + sin 60 j AD = 1 i + 2 sin 60 j AE = 0 i + 2 sin 60 j AF = -cos 60 i + sin 60 j sum of x components = 3 sum of y components = 6 sin 60 = 6 (sqrt3 /2) = 3 sqrt 3 magnitude = sqrt(3^2 + 9*3) = sqrt 36 = ...
  53. Physics

    Ke = (1/2) m v^2 + (1/2)I omega^2 you have everything there but omega, the angular speed, but you know that omega = v/R = 4.0/0.10 = 40 rad/second
  54. math

    yes. 2/6 = 1/3
  55. math

    The team shoots ?????????? goals in their sixth
  56. Physics

    time to stop = t v = Vi - 10 t 0 = 40 - 10 t t = 4 seconds to stop d = average speed during stop * time = 20 * 4 = 80 meters
  57. math

    They run up and down like free range cattle.
  58. math

    plug and chug (y-k)^2 = 4a (x-h) k = 8 given h = -9 given distance from vertex to directrix = a distance from -9 to - 16 = 7 = a (positive for directrix to the left of the vertex) so (y-8)^2 = 28 (x+9)
  59. math

    9x^2 + 9y^2 + 72x ? 108y + 368 = 0 well put all the x stuff on the left first maybe 9x^2 + 72 x = -9 y^2 +108 y - 368 divide by 9 x^2 + 8 x = -y^2 +12y - 368/9 complete square on left by adding(8/2)^2 = 4^2 = 16 to both sides x^2 + 8 x + 16 = -y^2 +12 y - 368/9 + 144/9 (x+4)^2...
  60. World History

    Better Ulan Bator ?
  61. Chemistry

    well, first, isotopes are different masses of atoms of the same element. In other words they have the same number of protons but a different number of neutrons. Now some such isotopes are unstable. Some like carbon 14 (regular carbon 12 with two extra neutrons) take a long ...
  62. math

    well the middle is halfway between (8/2 , -12/2) = (4,-6) center so (x-4)^2 + (y+6)^2 = r^2 try a point like (1,-7) (-3)^2 + (-7+6)^2 = r^2 9 + 1 = r^2 so r = sqrt 10 = (x-4)^2 +(y+6)^2 = 10 ========================check with other point (7,-5) (3)^2 + (1)^2 = 9 + 1 = 10 good...
  63. Pre-Calculus

    like t = y/2 then x = t^2 = y^2/4 so y^2 = 4 x but y = r sin T x = r cos T so r^2 sin^2 T = 4 r cos T r sin^2 T = 4 cos T r =4 cos T/sin^2T = 4 cot T csc T
  64. Pre-Calculus

    First you try.
  65. Physics

    v = Vi - g t at the top, v = 0 and t = 1.6/2 = 0.8 s g = 9.81 m/s^2 approximately so 0 = Vi -9.81(0.8) Vi = 9.81(0.8) meters/ scond
  66. Pre-Calculus Help?

    Then post your attempts.
  67. Pre-Calculus Help?

    Hey, you try some now !
  68. Pre-Calculus Help?

    x(t) = e^-t x^-2 = (e^-t)^-2 = e^2t 3 x^-2 = 3 e^2t = 3/x^2 = y
  69. math

    now if f(x) = x^n f(x+dx) = (x+dx)^n = x^n + n x^(n-1) dx + [n(n-1)/2!]x^(n-2) dx*2 ..... + ....dx^bigger f(x) = x^n still -------------------------subtract f(x+dx) -f(x) = n x^(n-1)dx+[n(n-1)/2!]x^(n-2) dx*2 ..... divide by dx [f(x+dx) -f(x)] /dx = n x^(n-1) + [n(n-1)/2!]x^(n...
  70. math

    f(x+dx) = (x+dx)^2 = x^2 + 2 x dx + dx^2 f(x) = x^2 ------------------------ subtract f(x+dx) - f(x) = 2 x dx + dx^2 divide by dx [ f(x+dx) - f(x) ] / dx = 2 x + dx let dx ----> 0 = 2 x the end d/dx (x^2) = 2 x is now established in your mind forever.
  71. Calculus

    typo, radius 2 I think
  72. Pre-Algebra

    Yes, although not since I was a young man lobstering and ground fishing out of Gloucester, Massachusetts.
  73. Pre-Algebra

    By the way this is a 3, 4, 5 triangle 9 + 16 = 25
  74. Pre-Algebra

    The hypotenuse is 20 one of the legs is 12 what is the other leg? 12^2 + x^2 = 20^2 = 400 x^2 = 400 - 144 x^2 = 256 x = 16 and yes, I am a fisherman.
  75. calclus

    https://www.jiskha.com/display.cgi?id=1526514290
  76. calclus

    Well, if you were a boat navigator you would use the 45 degree trick. Measure that distance from you to that road. That distance, d, should be perpendicular to the road. Now look 45 degrees right (or left). The distance along the road to that point on the road from your ...
  77. physics

    first 250 km/hr = 250,000 meters / 3600 seconds = V acceleration = rate of change of velocity = change in V / change in time = (250,000/3600) / 2.2 meters/ second^2
  78. physics asap

    second one Again the mass does not matter (1/2) m v^2 = m g h v = sqrt (2 g h) (remember that)
  79. physics

    his mass has nothing to do with it. Vi = 4.7 how long to reach top? v = Vi - g t 0 = 4.7 - 9.81 t t = .479 seconds up H = 3.8 + Vi t - 4.9 t^2 h = 3.8 + 4.7(.479) - 4.9 (.479^2) h = 3.8 + 2.25 - 1.12 h = 4.93 meters stopped above ground, falls from there 4.93 = 4.9 t^2 t = 1 ...
  80. maths

    You are welcome.
  81. maths

    I read even numbers so increased by 2 each time. Just do increase by 1 same system, same answer
  82. maths

    [ n+ (n+2) + (n+4) + .....(n+12) ] /7 = 16 [ (n+2) + (n+4) + .... (n+12) ] = 108 ==================================== well, multiply the first one by 7 [ n+ (n+2) + (n+4) + .....(n+12) ] = 16*7 = 112 [ (n+2) + (n+4) + .... (n+12) ] = 108...
  83. math

    You are welcome.
  84. math

    y distance = 40 x distance = 30 d = sqrt (40^2 + 30^2) the hypotenuse = 50 I suspect (3,4,5 triangle)
  85. physics

    How about 4184 J/kg deg C ? https://water.usgs.gov/edu/heat-capacity.html
  86. Physics

    https://www.jiskha.com/display.cgi?id=1526419154#1526419154.1526420002
  87. Math

    https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html a = 4 d = 4 and do you not have a text book ?
  88. Physics

    Well, they usually follow some sequence, generally something like a geometric sequence. 2 4 8 16 32 64 ..... If you left 8 out you would notice.
  89. Quadratic Functions and Equations

    well, (100+2w)(25+2w) = 3 (100*25) 2500 + 250 w + 4 w^2 = 7500 w^2 + 62.5 w - 1250 = 0 agree with bobpursley
  90. Probability

    possible outcomes 1 | 1 2 3 4 5 6 2 | 1 2 3 4 5 6 3 | 1 2 3 4 5 6 4 | 1 2 3 4 5 6 5 | 1 2 3 4 5 6 6 | 1 2 3 4 5 6 of those 36, 5 of them add to 8
  91. Pre-Algebra

    ....and by the way, Google distributive property of multiplication for example: http://www.math-worksheet.org/multiplying the way I think of it is (a+b+c)(d+e+f) = a(d+e+f) +b(d+e+f) +c(d+e+f) = ad+ae+af+bd+ ....... get it :)
  92. Math

    3 years = 36 months .07/12 = .00583333.... 1.00583333...^36 = 1.232925587 1.232925587 p = 30,000 p = 24,332.37
  93. math

    So do it. -10 = m (1) + b -2 = m (-7) + b ---------------------- subtract
  94. math

    d = k x + b by the way b is un stretched length 12 = 2 k + b 18 = 5 k + b ----------------- subtract -6 = -3 k k = 2 then b = 8 25 = 2 m + 8
  95. math

    (12t^6 - 8t^8) ÷ (2t^3) 2 t^3 ( 6 t^3 - 4 t^5) ÷ (2t^3) so ( 6 t^3 - 4 t^5) agree
  96. Math

    3,3 3,6 6,3 6,6 is 4 out of 36 = 1/9
  97. Math

    6 taken 4 at a time with no order 6!/[4!(2!) ] = 6 *5 / 2 = 15
  98. physics

    Hg is about 13.5 times water density of about 1 gram/cm^3 50 mL = 50*10^-3 Liters liter is 10^3 cm^3 so we have 50 cm^3 13.5 g/cm^3 * 50 cm^3 = 675 grams = .675 kg if you want weight not mass m g = .675 * 9.81 Newtons
  99. Math

    agree first one 9/36 = 1/4 agree second one 3/36 = 1/12
  100. Physics

    (1/2) rho v^2 + p = constant Q = volume flow rate = 275 kg/min * 1min/60 s * 1 m^3 / 1200 kg = 0.00382 m^3/second so v skinny pipe = 0.00382 / .068 = 0.0562 m/s v fat pipe = 0.00382 / 0.083 = 0.0460 m/s p fat pipe - p skinny pipe = (1/2)*1200 *(.0562^2 - .0460^2) = 600*0.00104...
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