Posts by Damon

Total # Posts: 33,079

  1. Physics

    (M1/M2) ?(h1/h2)
  2. Anything

    14 * 42 - 21 = 588 -21 = 567
  3. Algebra 1

    -1=2(5)+b yes, correect now -1 = 10 + b b = -11 so y = 2 x - 11
  4. physics

    if d is distance between buildings: tan 51 = 21/d so d = 21 / tan 51 if h is the ADDITIONAL height of big building tan 46 = h/d h = d tan 46 h = (21/tan 51) tan 46 total height = 21 + h
  5. physics

    sin A = 24/45 A = sin^-1 (24/45) A = 32.2 degrees
  6. Trig

    component of weight down slope = w * sin 5.7 component of weight perpendicular to slope = w * cos 5.7
  7. Dynamics

    You need a force to balance mass times centripetal acceleration. That force is provided by the weight times the coefficient of friction.
  8. Dynamics

    mass * centripetal acceleration * height of center of mass * cos A = mass * g * height of center * sin A sin A/cos A = (v^2/R) / g = tan A 15 m/h * 5280 ft/m * 1 h/3600 s = 22 ft/s v^2/R = 22^2/50 = 9.68 ft/s^2 9.68 / 32 = .3025 = tan A so A = 16.8 deg
  9. physics

    F sin 30 = 200 N |F| = 400 N F = 400 cos 30 i + 400 sin 30 j or since you did not say what quadrant the force is in F = 400 cos 30 i - 400 sin 30 j or F = -400 cos 30 i + 400 sin 30 j or F = -400 cos 30 i - 400 sin 30 j I assume that amit means at MIT ?
  10. System of Equations

    football for example: starts at (0,0) vertex at (16, 14) {get it ?} ground again at ( (32,0) a (y - 14) = (x-16)^2 or something maybe? what is a? goes through (0,0) so -14 a = 16^2 = 256 a = -18.3 approx so -18.3 (y-14) = (x-16)^2 = x^2 - 32 x + 256 = -18.3 y + 256 or -18.3 y...
  11. Algebra

    x(75-x) = 1250 75 x - x^2 = 1250 x^2 - 75 x + 1250 = 0 https://www.mathsisfun.com/quadratic-equation-solver.html yes 50, 25 :)
  12. Electrical trade theory

    Can be split thin good insulating dielectric
  13. Physics

    stops ???????, why ???
  14. Physics

    Force = change in momentum/ change in time in other words the max force is the max slope of the impulse versus time curve
  15. Physics

    http://www.mathpages.com/home/kmath114/kmath114.htm This is probably what your big ball little ball problem was supposed to be about as well.
  16. Physics

    force = work done / distance Hey, let us see what you have done yourself.
  17. Physics

    10 * 9.81 * 1.3 Joules
  18. Physics

    Oh, I gave you the power the work = energy = (1/2) m v^2
  19. Physics

    (1/2) m v^2/ time once again now try some yourself please.
  20. physics

    No, just do mgh, assume no speed at top :)
  21. physics

    3 cm = .03 meters E = (1/2) k x^2 E = (1/2)(750)(.0009) Joules
  22. Physics

    But you have a typo I suspect. No way 100 kg is moving at any such speed at five cm. Maybe 5 m or 1 kg or something.
  23. calculus2

    if z = x^.5 dz = .5 x^-.5 dx or dx = 2 x^.5 dz = 2 z dz and you have 2∫ z arctan(z) dz but http://www.wolframalpha.com/input/?i=integrate+z+tan%5E-1+z+dz so (z^2+1) arc tan (z) - z + constant now put z = x^.5 back in
  24. Math - Calculus

    top 4 x bottom 4 x corners vertical 4 h 8 x + 4 h = 36 h = (36 - 8 x)/4 = 9 - 2 x (part i.) v = x^2 h = x^2 (9 - 2 x) = 9 x^2 - 2 x^3 dv/dx = 0 for max or min dv/dx = 18 x- 6 x^2 = 0 6 x ( 3 - x) = 0 x = 0 is minimum of course x = 3 is maximum then
  25. Math - Calculus

    length = 16 - 2 x width = 6 - 2 x height = x so V = x(6-x)(16 - 2 x) now I did that top problem for you. Do this one the same way
  26. probability with casework

    oh + die - coin -die - coin = 1/3* 1/2 *1/3 = 1/18 11/36 + 1/18 = 11/36 + 2/36 = 13/36
  27. probability with casework

    I get die - coin - coin - coin = 1/3 * 1/2 *1/2 = 1/12 die - die - die - coin = 2/3 * 2/3 * 1/2 = 4/18 = 2/9 so 1/12 + 2/9 = 3/36 + 8/36 = 11/36
  28. Calculus check my answers

    whoops ! Go with Steve
  29. Calculus check my answers

    dy/dx = 0.2 constant slope is a parabola ??? first trap = (1/2)(1+3)(1.1 - 1) second = (1/2)(3+5)(1.3 -1.1) etc
  30. Check my calc please

    integral is t^2 + 2 t + constant so at t = x minus at t = 1 x^2 + 2 x + c - 1^2 -2 - c = x^2 + 2 x - 3
  31. Calculus check

    Yes, the slope is always positive, goes up forever.
  32. Calculus

    I guess you mean f(x) = x?-6 [?(36-t^2) ] dt in general ? (p^2-u^2)^.5 du = (1/2)[ u sqrt(p^2-u^2)+p^2(sin^-1(u/p) here p = 6 , u = t (1/2) [ t sqrt (36-t^2) + 36 sin^-1 (t/6) ] at t = x - at t = -6 (1/2) [ x sqrt(36-x^2) +36 sin^-1 (x/6)] - (1/2) [-6sqrt(36-36) + 36 sin^-1(-...
  33. Algebra

    do you mean f(x) = 3 x^2 / (x-2) ??? if so then f(4) = 3 * 4^2 / (4-2) = 3*16 / 2 = 3 * 8
  34. Physics

    http://www.physicsclassroom.com/class/circles/Lesson-4/Mathematics-of-Satellite-Motion and https://physics.info/orbital-mechanics-2/practice.shtml
  35. science

    find potential energy of stopped electron .01 meters from another one. k e^2/.01 Double that. That is the work done to bring the electron in from infinity. That is the kinetic energy required at infinity (1/2) m v^2
  36. Physics

    Remember potentials add. bring m1 into .04 m from m2 and m4 and .04*sqrt 2 from m3 get Pe remember G MM'/d then do m 2 in between the other 3 then m3 , then m4 then add
  37. phisics

    If mirror is level facing down incoming ray is headed East 65 North which is 25 clockwise from North outgoing ray is headed East 65 South which is 155 clockwise from North turned from 25 to 155 which is 130 degrees (which is 65 + 65 of course)
  38. Chemistry

    2HCl + Li2CO3 = 2LiCl(aq) + CO2(g) + H2O BUT LiCl is in the form Li+ and CL- no precipitate so they tell you to say no reaction, although CO2 bubbles off indicating that there was a reaction :) Beats me.
  39. Physics

    The impulse is the change of momentum 0.06 (31 - - 51) = .06(82) toward the net It does negative work slowing the ball down and then positive work speeding it up. [force opposite to motion then force in direction of motion] -(1/2)(.06)(51)^2 +(1/2)(.06)(31)^2 ignoring losses ...
  40. Chemistry

    20 * .5^(30/8.07)
  41. Chemistry

    how many half lives? 10 * 60 = 600 600/231 = 2.6 (1/2)^2.6 = .165 .165*100 = 16.5 %
  42. math

    23 + 5x ?
  43. ELA

    I’m Mayor Kenndrick. I’m thrilled to announce the launch of Wessex County’s first community garden here at South Falls High School. Either half can perfectly well stand alone. So I agree with you :)
  44. science

    1. There is no vertical motion, so no vertical acceleration. 2. The velocities are constant anyway, again no acceleration. So weight = m g = about 90.6 * 9.81 Newtons Someone is trying to confuse you.
  45. chemistry

    K2CO3 + 2 HCl --> 2 KCl + H2O + CO2 so 2 HCl mols for every K2CO3 mol How many HCl mols did we use? 40 cm^3 * 1 liter/1000 cm^2 = .04 liters .01 * .04 = .0004 mols of HCl so there were 0.0002 mols of K2CO3 mol mass K2CO3 = 39*2 + 12 + 16*3 = 138 grams/mol 138 *.0002 = .0276...
  46. chemistry

    Huh? 6 * 10 = 60 60/12 = 5 times
  47. Math

    circumference of hour hand circle = 2 pi *9 in one hour it goes circumference / 12 so distance = 18 pi/12 = 1.5 pi now the minute hand circumference = 2 pi * 12 it goes all the way around so answer = 24 pi - 1.5 pi = 22.5 pi
  48. calculus2

    How high is the top of the spout from the center of gravity of the tank ??? radius + 3 = 9 + 3 = 12 meters So you have to lift the weight of the water 12 meters. mass of water in tank = m = (4/3) pi r^3 * 1000 Kg weight = w = m g = 9.8 * m work = weight * distance lifted = (4/...
  49. Calculus

    You are welcome.
  50. Calculus

    Take a look at the one Steve just showed William how to o: https://www.jiskha.com/display.cgi?id=1530213278
  51. Calculus

    ( I am a Naval Architect :)
  52. Calculus

    slight oversight I think (1/2)(1/6) [ f(1) + 2 f(7/6) etc
  53. Calculus

    d^2s/dt^2 = a = 40 ds/dt = v = 40 t - 20 [so v is -20 when t = 0] s = (40/2 ) t^2 - 20 t + 10 [ so s is 10 when t = 0) s = 20 t^2 - 20 t + 10 feet
  54. physics

    3 , 4 , 5 right triangle so distance = 10 If 8 in the x direction and then 6 in the y direction then tan A = 6/8 = 3/4 where A is angle above x axis A = 37 degrees approximately
  55. Maths

    1 - 3/5 = 2/5 3/4 * 2/5 = 3/10 1/4 * 2/5 = 1/10
  56. physics

    W = (1/2) k x^2 .040 meters = x F = k x 15 = k (.04) k = 15/.04 = 375 so W = (1/2) (375) (.04)^2
  57. physics

    area you sure you mean .055 cm and not .055 m ? F = k x .8 = k *.00055 x + 1.5 = F/k + 1.5 = 3.2 *.00055/.8 + 1.5
  58. Maths

    if x^2 + d x complete square x^2 + d x + (d/2)^2 here (4/2)^2 = 4 x^2 + 4 x + 4 = (x+2)^2
  59. Physics

    find local g a = -g v = Vi - g t h = Hi + Vi t - .5g t^2 here Hi = 1 Vi = 0 so h = Hi - .5g t^2 Hi = 1 h = 0 at ground 0 = 1 - .5 g t^2 .5 g (.7)^2 = 1 .5 * .49 g = 1 .49 g = 2 g = 4.08 m/s^2 weight = m g = 60 * 4.08 Newtons ====================== r = 1.6*10^6 Newton - law of ...
  60. Physics

    You did not give the current direction except to say it is north of east. I will say it is y degrees north of east. In that case the water is moving Wn = 1.5 sin y is water north speed We = 1.5 cos y is water east speed say you head x degrees west of north Sn = 5.5 cos x = ...
  61. Physics

    atta go :)
  62. Physics

    then v = 0 - a t = - g t = -9.81 t h = Hi + 0 t -9.81/2 t^2 h = 1.95 - 4.9 t^2 ground is h = 0 so when it hits the floor t^2 = 1.95.4.9 solve for t Now for t seconds, the horizontal velocity was constant = 24.5 m/s x = v t = 24.5 t
  63. Physics

    Now the vertical problem is another matter entirely. The ball has no initial speed up or down F = - m g is the vertical force therefore m a = - m g a = -g constant acceleration down of about 9.81 m/s^2
  64. Physics

    There are no horizontal forces. Therefore there is NO change in horizontal velocity !!!
  65. geometry

    times -10 2. DRAW IT !!! 3. -1*-1 = +1 and 1^2 = 1, 2^2 = 4, 3^2 = etc 4. you can do this.
  66. Physics

    6.1*4.2 = 25.62 max 5.9*3.8 = 22.42 min difference between max and min = 3.2 divide by 2 = 1.6 nominal = 6*4 = 24 so 24 +/- 1.6
  67. physics

    from left end where x = 0 b up at x = 2.0 10 down at x = 3.5 m up at x = 4.0 20 down at x = x and m = 3 b =================== forces up = forces down b + m = 10 + 20 = 30 moments clockwise = moments counterclockwise about x = 0 10*3.5 + 20 x = b * 2 + m *4 so 20 x = 2 b + 4 m...
  68. chem

    2.48*10^5 Pascals 1 atm is 1 bar = 10^5 Pascals so 2.48 bar 1860.15 is about 1860 It is NOT about 186 !!!!!! You could say it is 1.86 * 10^3 though
  69. geometry

    You are welcome.
  70. geometry

    by the way lines in #2 and #3 are parallel, so pick any old point on one of them
  71. geometry

    I will not do them all for you, they are all virtually the same. 1) Given the following line and point not on the line, find the distance between them. y = 7x + 5 (-8,-1) ============================== find a line perpendicular to that one through that point slope = m' = -...
  72. Math probability

    now if the distance from 0 to 1 is 2*.43 sigma, what is sigma?
  73. Math probability

    click scond circle put in area = .3333 and area = .6667 and you will get that -.43 and + .43 which means the mean is halfway between 0 and 1 :)
  74. Math probability

    http://davidmlane.com/hyperstat/z_table.html
  75. world history

    A is correct. Despite being started in Nederland and representing Dutch interests it was one of the first multinational corporations and initiated trade with the Dutch East Indies much of which is now Indonesia and the Spice Islands.
  76. science

    - gain in potential energy due to going up
  77. Physics

    volume of oak under water = 15*15 * 10.5 so Archimedes says mass of oak = density of water * volume under water = 1 g/cm^3 * 15*15 * 10.5 total volume of oak = 15*15*15 density = mass/volume = 1 g/cm^3 * 10.5/15
  78. Physics

    assume you mean what fraction of the VOLUME is under water density = 570 kg/m^3 where water is 1000 kg/m^3 UNITS MATTER !!! mass of wood = 570 * volume = 200 mass of water displaced = 1000 * volume under water so 1000 * volume under water = 200 = 570 * volume so volume under ...
  79. Math

    9. 6 - -2 = 8 6 - -1 = 7 6 - +3 = 3 11. hint 2*-2 + 1 = -3 2*0 + 1 = 1 2*1 + 1 = 3
  80. Science

    Ice at 30 deg C??? Not likely but anyway specific heat of ice (about 2 J/gram deg c) does not matter in the end here call it sh heat into cold ice = heat out of hot ice 5 (T - -20) * sh = 10 (30-T) * sh 5 T + 100 = 300 - 10 T 15 T = 300 T = 20 BUT I doubt the whole thing ...
  81. math

    joh = 1 y / 2 h m = 1 y / 3h so (1/2 + 1/3) yard per hour together = 5/6 y/h (5/6) yards/hr * t hr = 1 yard t = 6/5 hours
  82. Math

    p = 2 L + 2 w = 728 so L + w = 364 and L = (364-w) A = L w A = (364-w)w = 364 w - w^2 dA/dw = 0 at max or min = 364 -2w so w = 182 L = 364-w = 182 LOL, a square or if you do not know calculus w^2 - 364 w = -A complete square to find vertex w^2 - 364 w + (182)^2 = -A+182^2 (w-...
  83. Physics

    first figure out how long it took the block to fall to the floor: h = (1/2) g t^2 t = sqrt (2 h/g) so it went 2 meters in t seconds so the horizontal speed was u = 2/t NOW you have a conservation of momentum problem u(2.5 + .008) = .008 v solve for v
  84. Math

    1.035 * 13.65
  85. Math

    distance = speed * time speed 1 = 75 speed 2 = 125 time 1 = t time 2 = t - 2 distances the same 75 t = 125 (t-2) 75 t = 125 t - 250 250 = 50 t t = 5 hours so what is 75 * 5 ?
  86. Science

    mass of water = 105.75 - 55.75 = 50 g so volume of water = 50 g (1 cm^3/g) = 50 cm^3 = vol of bottle mass of stuff = 123.75 - 55.75 = 68 g density of stuff = 68 g /50 cm^3 = 1.36 g/cm^3
  87. physics

    stretches 5 cm by whatever son is (100/son) * 5 cm + 20 cm
  88. math

    Heading vector: South = 550 cos 83 East = 550 sin 83 Wind vector - air moving: South = 85 cos 70 East = -85 sin 70 so in the end South 550 cos 83 + 85 cos 70 East 50 sin 83 - 85 sin 70 I think you can take it from there.
  89. math

    u + v = 5 i - 8 j + 1 k 5 j = 0 i + 5 j + 0 k u + v - 5 j = 5 i - 13 j + 1 k
  90. math

    Hey, you have a textbook I suspect that shows the trig formulas you need for example cos (2 T) = 2 cos^2 (T) - 1 or = cos^2(T) - sin^2 (T) I am not going to do the arithmetic for you
  91. science

    http://www.physicsclassroom.com/class/refrn/Lesson-3/The-Critical-Angle nr must be smaller than ni because there is no such thing as a sine with a value greater than one. As nr increases closer to n incident the critical angle gets closer to 90 degrees (sin 90 = 1.00) In other...
  92. Physics

    L = 5 d = 2*10^-3 r = 10^-3 A = pi r^2 = pi (10^-6) stress = 50 N / 3.14*10^-6 = 15.9 * 10^6 Newtons/ m^2 strain = delta L/L = .25*10^-3 / 5 = .05 *10^-3 = 50 * 10^-6 m E = stress / strain
  93. math

    What is t when h = 150 ? 150 = -4.9 t^2 + 58.8 t + 8.6 or 4.9 t^2 - 58.8 t + 141.4 = 0 solve quadratic https://www.mathsisfun.com/quadratic-equation-solver.html 8.67 - 3.33 = time above 150
  94. math

    a = 94/2 = 47 b = 47/2 = 23.5 x^2/47^2 + y^2/23.5^2 = 1 now google ellipse to find focus :)
  95. geometry

    8 b = 56 so b = 7 CD = 8 b + 7 b = 56 + 49 = 105
  96. geometry

    NQ = 4 m = 13 so m = 3 MQ = 5 m + 1 = 15 + 1 = 16
  97. math

    42 = 2*21 = 2 * 3 * 7 (lucky :) so log 42 = log 2 + log 3 + log 7 all base 7 but what is log 7 base 7 7^log 7 = 7 but that is 7^1 so log 7 = 1 if base 7 so log 42 = log 2 + log 3 + 1 no way I will add those numbers without my machine :)
  98. physics

    F = k x F = m g x = 0.021 meter m g = 2.3 * 9.81 so k (0.021) = 2.3 * 9.81 then omega = 2 pi f = sqrt (k/m) the 3.8 cm has nothing to do with it.
  99. Economics

    I agree with you. D is the only answer that makes sense. The short term loans posited in B would not help much and the other choices are total nonsense.
  100. problability

    had five apples p of red = 2/5 now have 4 apples one red p of red = 1/4 so 2/5 * 1/4 = 1/10 = 0.10 = 10%
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