Posts by bobpursley

Total # Posts: 47,518

  1. Physics

    consider mass, time, and length in your description.
  2. Physics

    PE at that altitude: mgh=1/2 m v^2 g=GMe/(Rearth+1.5e^6)^2 v=sqrt(3e6*g *2) use g from line above.
  3. Math

    take the implicit derivative. 2x Dx -7y^3*2x Dx-7x^2*3y^2 Dy=2yDy-2xDy-2yDx Dx(2x-14xy^3+2y)=Dy(2y-2x+21y^2) solve for Dx/Dy, then put in the point (-2,5) and solve. check my work.
  4. physics

    net force pulling: g(m2-m1) F=total mass*a a= g(m2-m1)/(m2+m1) d=1/2 a t^2 solve for t.
  5. Physics

    What is it you do not understand about this? https://www.softschools.com/formulas/physics/parallel_axis_theorem_formula/346/
  6. Physics

    1/2 mv^2=mgh Vescape= sqrt (2gh) but g=GMj/d^2 so... Vescape=sqrt(2GMj/h)
  7. chemistry

    Draw the lewis strutures first. Now consider https://viziscience.com/wp-content/uploads/2017/09/s2cl2-2.jpg If that is the structure, how could it possibly be a polar (one end charged)?
  8. English

    It seems to me you discussed issues, but you never addressed What Is the Secret to Reaching Someone With Words? a) consider using powerful ideas that they understand b) sticking to the topic, letting them figure the details (there is no better teacher than experience) Now on ...
  9. Charges

    why do you have absolute signs on the charges. The sign of the charge is important. force=kq(-q)/3^2 + kqq/6^2= kqq(-1/9+1/36)=kqq(-4/36+1/36)=kqq*3/36 where q=3e-6
  10. chemistry

    Nuts to just giving you the answer.
  11. science

    first, I like D. A is ok on second.
  12. Science

    electric fields is away from positive charges, by definition.
  13. math:^]

    a. PQ=(7-5)x+(3-4(y)=2 ,-1 RS=(4-8)x+(1-6)y=-4,-5 PQ+3RS=2 ,-1 +3( -4,-5)=(2-14,-1-15)=10,-16 magnitude= sqrt(10^2+(-16)^2)=sqrt(356) factoring 356 2*178 2*2*89 magnitude=2sqrt(89)
  14. science

    thanks. Is there a question here? Were they pushing in the same direction?
  15. LA

    http://sabian.org/looking_glass6.php Ok, after the first page or two....Alice is becoming sensitive, avoiding confrontation, avoiding arguing, and Humpty is..... Did that dialoge help you develope who Alice was, and who Humpty is?
  16. Vectors

    speed relative to ground: 240E+65*cos45E+65*sin45S combine like directions, then directionactual= arctan(S/E) south of East.
  17. Math

    Hmmmm. Triangles? Not enough info.
  18. Shell Method

    here it is about y=0. So the radius will be from y=y0 to y. https://www.khanacademy.org/math/ap-calculus-ab/ab-applications-definite-integrals/ab-shell-method/v/shell-method-for-rotating-around-horizontal-line see if that helps.
  19. Chemistry

    dissociation: lactic acid>>>H+ + act- ka= x*x/(.025-x) but you know x=10^-2.74=.001819 ka= .001819^2/(.025-.001819)=.001819^2/0.023181= 0.000142735904=10^-3.85 pKa= 3.85 check my math
  20. Angular acceleration

    well, in each rotation of the wheel, the wagon goes 2PI*r speed car=2PIr/timeforonerotation=w*r w=speedcar/r so change those speed in km/hr to m/s, find wi and wf angacceleration= (wf-wi)/3sec
  21. Science

    adding more lightbulbs will make them dimmer. the current in a series circuit is CONSTANT in each part of the circuit.
  22. chem

    the max volume is 10 ml. the 6 Molarity is the concentration of the HCl. You dont do anythign with that number.
  23. Science

    Primary sources can be used directly, as they appear in the natural environment: coal, oil, natural gas and wood, nuclear fuels (uranium), the sun, the wind, tides, mountain lakes, the rivers (from which hydroelectric energy can be obtained) and the Earth heat that supplies ...
  24. Physics

    sum of heats gained is zero. heatgainedhotwater+heatgainedbycoolwater=0 120*c*(Tf-50)+200*c*(Tf-10)=0 solve for Tf
  25. Physics

    and your work is? Snell's law is pretty straight forward.
  26. Physics

    Snell's law applies. The angle has to be measured from the normal, I assume by "prime" you mean normal.
  27. Physics

    even if they are end to end, the sum will be 25.
  28. Algebra (Final)

    If it is not in your text, burn your text. https://www.varsitytutors.com/hotmath/hotmath_help/topics/sum-of-the-first-n-terms-of-a-geometric-sequence
  29. Math

    area=PI*r^2 r= sqrt(area/PI)
  30. Math (Trigonometry)

    sin(5x)=sin(4x+x)=2sin4xsinx
  31. science

    glass
  32. Math

    of the 20x5 groups above, there are 11 with two or more late (**** means 2+late) 65926, 31459, ***31986, ***65809, 80462 ***27387, ***39075, ***46738, ***21986, ***59837 ***91384, ***10987, 26491,*** 68498, ***98796 32596, 26448, 31235, 63256, 53121 Pr=11/20
  33. Chemistry

    amount left=65*e^(-.693*15/3.8) put this in your google search window: 65*e^(-.693*15/3.8)=
  34. Maths

    L is longer ribbong length, S is shorter ribbon length L-17.5=S L/3=3S/4 L= 9S/4 9S/4 -17.5=S S(9/4-4/4)=17.5 S= 4*17.5/5=14 inches
  35. Sci

    if you destroy wetlands, you are probably not changing the ozone layer.
  36. math

    I already took the course, and test. What is your difficulty with this? Seems to me you need a pencil and graph paper, or a graphing calculator.
  37. Algebra 1

    rate combined=sum of rates= 1trip/1.5hr + 1trip/1hr= 2.5trips/1.5hr time to deliver= trips/rate= 1.5/2.5=3/5 hr
  38. Algebra 1

    let E be weight of expensive nuts, C be cheaper nuts E*8+C*5=10*6 value equation E+C=10 mass equation Solve it by any method, I will do determinants Det: 8-5=3 E= (60-50)/3=10/3 =3.33 lb C= 80-60 /3=20/3 =6.66 lb
  39. Science

    if you blow air thru a straw into a jar of lime water (CaO), it turns cloudy precipitating CaCO3. https://www.youtube.com/watch?v=xOoutdcV-WI
  40. english

    I only see bluntness. I think she is being stark blunt
  41. Calculus

    have you seen this? https://www.youtube.com/watch?v=fjcHK6GGqm8
  42. Math

    if secTheta=-13/5, then cosTheta=-5/13 cos^2 + sin^2=1 sin^2=1-25/169=144/169 sinTheta=12/13 (in second quadrant, positive0 sin(2Theta)=2sinTheta*cosTheta=2(12/13)(-5/13)= you do it. check my thinking
  43. Chemistry

    No
  44. Chemistry

    if H+ is 10^-5.35, so the acetate concentration the same. H acetate>><< H+ + aqcetate-
  45. Physics

    none are correct. Number 2 question is technically and issue of the word "stronger". Stronger in what sense? tensile strength? Magnetic properties? ductle? Ferrite is a brittle ceramic material, as the question is written, I would go with that. It is a poorly worded ...
  46. Physics

    and your thinking is????
  47. physics

    vf2=vi2+2ad so take the square root of your v2
  48. physics

    3. vf^2=vi^2+2g*3.8 will do it 4. same formula. vf^2=vi^2+2ad
  49. Social Science

    First, understand what a manifesto is: a public policy statement of goals and vision. Examples: a. <<And with your courage and with your compassion and your desire, we will build a Great Society. It is a society where no child will go unfed, and no youngster will go ...
  50. history

    that link is an excellent summary of what happened, but obviously, Napoleon would not agree with the outcomes as stated....He would have preferred a spin that favored him more as the person who was making France great again. He liked to be the star of the show, pushed himself ...
  51. Chemistry

    How many mL of water would you add to 32 mL of 0.62 M ammonium chloride stock solution to make a 0.3 M solution? >> Another method. You are diluting it .62/.3 = 2.06 times. That means one part original, and then add 1.06 parts water. if one part is 32ml, then 1.06 parts ...
  52. Science

    correct.
  53. vectors

    https://answers.yahoo.com/question/index?qid=20090914114948AAF9qjv
  54. math

    10/25=40/100= 40 percent
  55. Physics

    What is the wire wound around, or specifically, its permeability? http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/solenoid.html#c3
  56. Science

    heat=mass*heatvaporiazition.
  57. Chemistry

    It shifts to the left. More H2, more I2 is made, less HI, energy is absorbed (endo),
  58. Physics

    vf=at solve for a. put km/h into m/s, and 5min into seconds.
  59. Algebra

    multiply by sqrt30/sqrt30 you now have 4sqrt6*sqrt30/30 but sqrt 30=sqrt(5*6)=sqrt5*sqrt6 now you have 4sqrt6*sqrt6*sqrt5/30=24*sqrt5/30=.8 sqrt5
  60. Chemistry

    find moles of O2: 41.9/32= ... then, PV=nRT or T=PV/nR you have n, Pressure, Volume find temp triple check your units on R You need R in atm, liters, psi, temp in K
  61. Science

    a is correct
  62. physics

    There are a few fundamental characteristics of matter we have: a. That matter is a form of energy. b. That particles can have mass, charge, momentum, and have many characteristics of waves. c. Charge seems to be based in the fundamental characteristics of one of the quarks, ...
  63. Chemistry

    heat=mass*specheat*tempchange=122g*4.18J/(gC)*23C
  64. Physics

    sketch a diagram. How how off the ground is the child at the 30 deg point: Ans: h=2(1-cos30) a. child speed at bottom: KE=initialPE 1/2 m v^2=mgh v= sqrt (2gh) b. energy lost: initial PE-1/2 m(2)^2
  65. Science Answer Check

    7. there is a better answer.
  66. Chemistry

    yes, particles separate, thermal expansion
  67. Algebra

    If -3 were one die, then the possible sums of two dies would be -6,-5,-4,-3,-2,-1: avg -3.5 if -2 were one die, then the possible sums of two dies would be -5,-4,-3,-2,-1,0: avg-2.5 the figure all possibilities for the first die, and the avg sum on each. Add all the sums, ...
  68. Physics

    sum of heats lost is zero. -.022*Hf+.450*Cw(80-Tf)+.022(Cw)(0-Tf)=0 solve for Tf
  69. geometry

    volume=h*PI*r^2 smallest height will be at 7cm 315/PI*7^2=2.05cm largest height will be at 6.5cm 315/(PI* 6.5^2)=2.37cm
  70. Chemistry

    Na*Va=Nb*Vb .5875*3*10ml=.2625*Vb Vb= 10ml*(.5875/.2625)= about 22ml in my head
  71. Science

    abiotic. No including living things. Not A
  72. social studies

    https://history.libraries.wsu.edu/fall2015/2015/08/30/changes-in-oil-prices-and-how-they-affect-different-economies/
  73. Science

    What are factors in burning: Heat, Fuel, Oxygen. So hot temps mean more heat, so burning is increased.
  74. Math

    Hmmmm. I bet his horse's name is Sunday.
  75. physics

    vfinal=acceleration*time change km/hr to m/s
  76. socials

    They raised Hell to get the right to vote, and a constitutional amendments was passed to give them that right in US elections. Men in those days didn't think women were smart enough to vote.
  77. physics asap

    I just did the first on below.
  78. physics

    his final KE=KE at launch + PE at launch 1/2 mv^2=1/2 m 4.7^2 + m(9.8)(3.8) V^2=44+37 v= 9m/s
  79. Chemistry

    1. You need no website. If half is gone after 20 days, then after 40 days, half of half is all that remains: 1/4*200=50g 2. Molarity= mass/molmass * 1/volumeinLiters = 19.3/formalamassNaCl * 1/4 formula mass Na=23+35 check that. 3. pH+pOH=14 pOH=-log(OH)=-log (10^-9)=9 PH=14-9=5
  80. Chemistry

    they move apart.
  81. Chemistry

    they get closer together, and collide more often, and collide more often with the walls of the container.
  82. Physics

    time it takes the coin to fall: h=1/2 g t^2 t=sqrt(2h/g) time it takes sound to come back: h/vs given: those times add to 5.2 seconds 5.2=sqrt(2H/g)+h/v a quadratic: let u=sqrt h so u^2=h u^2/v+u(sqrt2/g)-5.2=0 u^2+u*vsqrt(2/g)-5.2v=0 calculate v for that temerature, then use ...
  83. Math (Help)

    notice for each increase in x of one, y goes down by 5, so it is a linear equation. general form: y=mx+b using two data points (-2,9; 2, -11) 9=-2m+b -11=2m+b add the equations -2=2b or b=-1 with b=-1, then 9=m(-2)-1 m=-5 y=-5x-1 should do it.
  84. CHEMISTRY

    changing concentrations to Normality: 2.5e-2 M= 5e-2N on sulfuric .03M KoH=.03N KOH Na*Va=Nb*Vb Va=(.03/5e-2)125ml=75ml
  85. Social Studies

    Wouldn't it depend on your product or service you are planning? http://francistapon.com/Books/The-Hidden-Europe/Where-is-Eastern-Europe-and-what-countries-are-in-it
  86. Chemistry

    you have 3.44/1.86 moles. molemass=11.32*3.44/1.86
  87. Maths, physics, science

    rate=volume(time) rate*time=volume time=volume/rate= 1.5m^3/(PI*25*3) seconds
  88. Social Studies

    On the peace question, A is probably the best answer, but with fingers crossed. Bill Clinton did make the hyprocrisy of the UK evident, and it did spur some movement. On the second: lower interest, easier money, more things are bought. Why would anyone default on a loan if the...
  89. Science

    just follow the directions.
  90. Chemestry

    assume 100Liters, mass then is 89.7 grams PV=nRT so you have P, v(100lites), n=mass/molmass and you know mass, Look up R for your units, and you know temperature
  91. chemistry

    molarity=(:mass/molmass)/volume mass=molarity*molmass*volume=58.4*1.0*.300=17.5grams
  92. Chemistry

    So what is the other 9 percent of the unknown compound?
  93. Chemistry

    you percents only add to 91 percent
  94. Quadratic Functions and Equations

    well, the dimensions of each end is (25+2w)w and the side (100w). the total lawn area A=2(25+2w)w+2(100w)=50w+4w^2+200w=4w^2+250w=2*2500 4w^2+250w-5000=0 w^2+62.5w-1250=0 solve the equation. check my thinking d
  95. ELA

    C is ok.
  96. physics

    mass=density*(thickness)(diameter/2)^2*PI = 7500*.05*(.250)^2* PI=73.6kg check my calculations
  97. math

    in matrix form 6,-3,-10 2,1,-9 3x r2, add r1,r2 12,0,-37 x=-37/12
  98. Chemistry

    I recommend look at the definitions of each: keyword: google search.
  99. Math

    correct
  100. Physics

    66=h1-h2=1/2 gt^2-1/2 g(t-1)^2 solve for time t.
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