Thursday
November 27, 2014

Posts by Damon


Total # Posts: 19,590

Chemistry
If there are 25 mg of water in a typical drop of water, how many drops of water would react completely with 2 mmol of phenylmagnesium bromide? How do I set up the problem?
November 9, 2014

Physics
sum of vectors, not product Pa =3.2[ 2.3 i + 4.2 j] = 7.36 i +13.44 j Pb =2.9[ -1.8 i +2.7 j] =-5.22 i +7.83 j P = (7.36-5.22) i +(13.44+7.83) j
November 9, 2014

Physics
initially p1 = 4 i + 2 j p2 = -3i + 3 j total p = 1 i + 5 j final p must be the same final p1 = px i + py j p2 = 6 i - 3 j px + 6 = 1 px = -5 vx = -5/2 = -2.5 py -3 = 5 vy = 5/2 = 2.5 so v = -2.5 i + 2.5 j
November 9, 2014

physics
no question was asked
November 9, 2014

Physics
m g h + (1/2)m v^2 = total energy = constant h is height above hanging straight down mg(2-2 cos 30)+.5m*9 = total energy = m g (2 -cos max angle when v = 0) notice m has nothing to do with this problem, cancels = mg(2-cos45) +.5 m v^2
November 9, 2014

Physics
Ke - work done against friction = (1/2)kx^2 (1/2)mv^2 - .3 m g (.2+x) = (1/2)(800)x^2 (1/2)*2*9 -.3*2*9.8(.2+x) = 400 x^2 solve quadratic for x why are you talking about m g h ??? it fell on horizontal plane?
November 9, 2014

Math
b did both draw Venn diagram fri---both- weekend |20-b | b |29-b| 20-b + b + 29-b = 40 49 - b = 40 b = 9 11 fri , 9 both , 20 weekend
November 9, 2014

Calculus
You are welcome.
November 9, 2014

Calculus
Do you mean? y= (x^3+8)/(x+2) ???? or what you typed? If my guess is correct then (bottom dtop/dx -top d bottom/dx)/bottom^2 =[(x+2)(3x^2)-(x^3+3)(1)]/(x+2)^2 =[3x^3+6x^2-x^3-3]/(x+2)^2 = (2x^3+6x^2-3)/(x+2)^2
November 9, 2014

calc
x y = 50 2 x + y = p 100/y + y = p dp/dy = 0 for min = -100/y^2 + 1 y = 10 x = 5 p = 20 feet of fence
November 9, 2014

Algebra
if x = 6 then f(x/2) = f(3) = 4 y = 4/2 = 2 (6,2)
November 9, 2014

Algebra
if x = 3 then f(x) = 4 so y = 4 + 4 = 8
November 9, 2014

Physics, please!
I used g = -10, you do it with your g
November 8, 2014

Physics, please!
I guess he kicked it horizontally? Hi = 22 0 = Hi - (1/2)(10) t^2 4.4 = t^2 t = 2.1 seconds goes 17 meters horizontal in 2.1 seconds u = 17/2.1 = 8.1 m/s
November 8, 2014

Physics
F = mu m g work = F d = mu m g d Ke lost = (1/2) m Vo^2 Vo^2 = 2 mu g d mu = Vo^2/(2gd)
November 8, 2014

Algebra 2
4x(x-6)-x(x-2)=-24 4 x^2 - 24 x - x^2 + 2 x + 24 = 0 3 x^2 -22 x + 24 = 0 18 and 4 I bet (3x - 4)(x - 6) ??? yes x = 4/3 or 6
November 8, 2014

Algebra 2
6 x^2 - 13 x + 6 = 0 we want 6 * 2 and a 1 to get 13 or 9 and 4 (3 x - 2)( 2x - 3 ) ah, 9 and 4 x = 2/3 or 3/2
November 8, 2014

Algebra
speed up = u -c speed down = u+c d = speed * time 3 = (u-c)1.5 3 = (u+c)1 1.5 u - 1.5 c = 3 1.5 u + 1.5 c = 4.5 --------------------- add 3 u = 7.5 u = 7.5/3 3 = 7.5/3 + c c = (9-7.5)/3 = 2.5/3 = .83333333333333333333333333
November 8, 2014

S.S.
Civil Rights Act of 1964? People are still discriminating against black people, particularly in the South
November 8, 2014

Algebra 2
we know that 7*7 = 49 and 49+1 = 50 so we know what to do 7 p^2 - 50 p + 7 = 0 (7 p - 1) ( p - 7) = 0
November 8, 2014

Calculus (math)
I tried method 2 but gave up about an hour ago. I do not think there is any trick, just plug and chug.
November 8, 2014

Calculus
if you were supposed to use feet instead of meters as your other problem that I just saw, use 32 ft/s^2 for g not 9.81 m/s^2
November 8, 2014

Calculus
a = g = -9.81 m/s^2 v = -gt = -9.81 t h = Hi - (1/2) g t^2 = Hi - 4.9 t^2 b) h at t = 0 = Hi h at t = 3 = Hi-4.9 t^2 = Hi - 44.1 m/s average = (-44.1)/3 = - 14.7 m/s c) at 0 v = 0 at 3 v = -9.81*3 = -29.4 m/s at 6 v = -9.81*6 = -58.9 m/s d) well I am not about to Google Hi Hi...
November 8, 2014

calculus
I mean e^x as x --> big negative is 1/e^big positive
November 8, 2014

calculus
e^-a = 1/e^a
November 8, 2014

calculus
e^x as x --> big negative is 1/e^big negative
November 8, 2014

calculus
Thought I answered this -x/e^x e^x >> x for large x
November 8, 2014

Math
C --> y S --> 3 y J --> 3 y + 50 y + 3 y + 3 y + 50 = 7 y + 50
November 8, 2014

Calculus
Oh good grief, feet :( old text had initial speed 16 ft/s up ? I guess ? h = 32 + 16 t - 16 t^2 0 = 32 + 16 t - 16 t^2 solve quadratic t = [ -16 +/- sqrt ( 256+2048) ] /-32 t = 2 seconds v = dh/dt = 16 - 32 t = 16 - 64 = -48 ft/s
November 8, 2014

Algebra 2
4 x^2 + 2 x - 2 = 0 2 ( 2 x^2 + x - 1) = 0 (2x-1)(x+1) = 0 x = 1/2 or -1 5 x^2 + 34 x - 7 = 0 (5x-1)(x+7) = 0 etc
November 8, 2014

Algebra 2
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx x= 1, y=2, z = 3
November 8, 2014

Calculus
x --> + oo of -x/e^x
November 8, 2014

Physics
sqrt (251^2 + 80^2)
November 7, 2014

Physics
How long to fall 10 meters? 10 = (1/2)(10) t^2 solve for t, time in air then 4 meters = u t solve foe u
November 7, 2014

Science Help!!!!
Yes, first it is burned in the engine to make CO2 The CO2 is used in photosynthesis to make wood and leaves and stuff, releasing the O2 for us to breathe.
November 7, 2014

physics
Problem entirely vertical assuming your straight line is horizontal Vi = 10 sin 46 v = Vi - g t delta h = Vi t - (1/2) g t^2
November 7, 2014

CAL
f'(x) or d f(x)/dx y' or dy/dx maybe?
November 6, 2014

Calculus
-4 cos^3 x^4 sin x^4 (4 x^3) = - 16 x^3 cos^3 x^4 sin x^4 how that is tan x2 whatever that is I can not imagine
November 6, 2014

Math
log 9 - log 300 2 log 4 + 4 log 3
November 6, 2014

Science
F2 + F1 = .450 (.750) F2 - F1 = .240 (.750) -------------------------- 2 F2 = .690(.750) etc
November 6, 2014

Physics
force down = 9.81*12 max friction force = 9.81 * 12 * mu forward force - friction force = m a 15 - 9.81*12 * mu = 12 (.2)
November 6, 2014

Math
I do not think so I think h = 300 - 16 t^2 she is accelerating DOWN 100 = 300 - 16 t^2 t^2 = 200/16 t = 10 sqrt 2 / 4 = 2.5 sqrt 2
November 6, 2014

Physics easier
http://outreach.phas.ubc.ca/phys420/p420_04/sean/
November 6, 2014

Hurricane Project for Physics Class
Physics (hard) http://www.psfc.mit.edu/library1/catalog/online_pubs/iap/iap2013/emanuel.pdf
November 6, 2014

Hurricane Project for Physics Class
Physics (hard) http://www.psfc.mit.edu/library1/catalog/online_pubs/iap/iap2013/emanuel.pdf
November 6, 2014

Hurricane Project for Physics Class
Click on hurricane in the upper right corner
November 6, 2014

Hurricane Project for Physics Class
http://coast.noaa.gov/hurricanes/#app=c64c&88cd-selectedIndex=1
November 6, 2014

Calculus
no v = w^2 h = (2300/3) h but h = (2300 -w^2)/4w
November 5, 2014

Calculus
v = w^2 h A = 2300 = w^2 + 4 w h 4 w h = 2300 - w^2 h = (2300 -w^2)/4w so v = w^2 [ (2300 -w^2)/4w ] v = 2300 w/4 - w^3/4 4 dv/dw = 2300 -3 w^2 = 0 for max w^2 = 2300/3 w = 27.7 cm etc
November 5, 2014

Math
2 w + 2 L = 18 so L = 9-w A = w L = 9 w - w^2 w^2 - 9 w = -A find vertex by completing the square for max A w^2 - 9 w + (9/2)^2 = - (A-81/4) (w -9/2)^2 = - (A-81/4) w = 9/2 for max area by the way that means 2 w = 9 and therefore 2 L = 9 so it is a square with sides = 9/2
November 5, 2014

Physics
No. To start it moving you must overcome the static friction. After that it gets easier. 648 * .86
November 5, 2014

algebra
sum of arithmetic series a1 = 1 d = 2 an = a1 + (n-1) d so a700 = a1 +(699)(2) sum = (a1 + a700)/n
November 5, 2014

calculus careful with parentheses
do you mean what you wrote 7 + 3 x^.5 or do you mean 3 [x+7]^.5 ??????????? anyway (x+1)(derivative of second) + (second) (1)
November 5, 2014

Calculus I
using T for theta dR/dT = (Vo^2 /9.81) cos2T (note max range when T = 45 degrees :) ) 100 dT/T = 2 dT = .02 T = .02 * pi/6 dR = (Vo^2 /9.81) cos2T dT 100 dR/R = cos 2T dT / sin 2T
November 5, 2014

physics
m g h = (1/2) m v^2 so h = (1/2) (v^2/g) mass has nothing to do with it
November 4, 2014

RIGHT TRIANGLE TRIG
You are welcome.
November 4, 2014

RIGHT TRIANGLE TRIG
sin 65 = h/150 assuming that the string hypotenuse is straight
November 4, 2014

Physics- linear acceleration
Find out how far the wagon went in 19 seconds d = (1/2) a t^2 = (1/2)(.3)(19)^2 each revolution or 2 pi radians the wheel rolls 2 pi r meters so divide d by (2*pi*.374) to find how many turns then multiply that by 2 pi to get radians (1/2)(.3)(19)^2 /.374
November 4, 2014

Math, Please Help! I don't understand!
I guess x is right and y is up final x = initial x + change in x final y = initial y + change in y beginning x = -2 moves one right -2 + 1 = -1 beginning y = -5 moves 3 up -5 + 3 = -2 b) (-1 , -2)
November 4, 2014

Algebra
f(f(x)] = p(px+q) + q f[f(f(x)) = p[p(px+q) + q] + q = p^2(px+q) + pq + q p^3 x + p^2 q + pq + q = 8 x + 21 = (p^3-8)x + p^2 q + pq + q = 21 this can not be a function of x or it would not be constant 21 so p^3-8 = 0 p = 2 4 q + 2q + q = 21 q = 3
November 4, 2014

Algebra
1. slope = 3 y = 3 x + b so to find b 2 = 0 + b b = 2 y = 3 x + 2 2. same way but slope = -1
November 4, 2014

Physics
find change in momentum .145(27+32) force = change in momentum/time = change in momentum /(1.5*10^-3 )
November 4, 2014

Physics
131 * 9.9 .00932 * 618
November 4, 2014

Calculus
x^2 - 6 = - y vertex on y axis, opens down (sheds water) so just do the right half half A = x y hA = -x (x^2-6) = -x^3 + 6 x dhA/dx = 0 at max = -3 x^2 + 6 x^2 = 2 x = sqrt 2 include left half length along x axis = 2 sqrt 2 if x = sqrt 2 y = 6 - x^2 = 6-2 = 4
November 4, 2014

Calculus
Oh, well I guess I found your point :) (15/26,5/13)
November 4, 2014

Calculus
rewrite as y = -(6/4)x + 1/4 line perpendicular has slope +4/6 = +2/3 y = (2/3) x + b we want it through 0, -1 -1 = (2/3) 0 + b b = -1 so y = (2/3) x - 1 where does that hit original line? (2/3) x - 1 = -(3/2) x + 1/4 4 x - 6 = -9 x + 3/2 13 x = 15/2 x = 15/26 then y = 5/13 ...
November 4, 2014

physics
change in momentum = .001 (300 - 700) time in block = .08/(average speed = .08 / [(700+300)/2] Force = change in momentum/time in block
November 4, 2014

Physics
F = m a solve for a then v = 0 + a t to get t: d = 3.3 = (1/2) a t^2
November 4, 2014

Physics
PLEASE CHECK FOR TYPOS slope of the air slope of air WHAT?
November 4, 2014

least to greatest fractions
6/9 is 2/3 if that is what you are asking. I have no idea what the second and third lines are about 4/40 is 1/10 2/5 is 4/10 maybe 7/10 is next ? 3/7 is 6/14 8/14 is 8/14 5/7 is 10/14 so next would be 12/14 = 6/7
November 3, 2014

math
y = 5 x + 100 your brother has the sign of the slope wrong
November 3, 2014

Algebra
q = [ (x+113)/2 ]^1/3 q = [ (137+113)/2 ]^1/3 q = 125^1/3 = 5
November 3, 2014

Math
-1.4 b = -28 b = 28/1.4 = 20
November 3, 2014

Algebra
y = x^5 - 1/3 inverse x = y^5 - 1/3 y^5 = x + 1/3 = -31/96 + 32/96 = 1/96 if y^5 = 1/96 then y =1/2.5 = .401
November 3, 2014

Calculus
cost of x tables = [160-.5(x-250)]x for x>/=250 c = 160 x + 125 x - .5 x^2 c = 285 x - .5 x^2 dc/dx = 285 - x max when x = 285 then c = .5*285^2 = 40,612.50 and c = 0 when x = 0 of course but also when x = 285*2 = 570
November 3, 2014

Algebra
f^-1(1) = 2 (when y = 1, x = 2) f^-1(2) = 5 f^-1(5) = 3
November 3, 2014

Physics
F = m a 12.1 = 5.9 a solve for a d = (1/2) a t^2 2.6 = (1/2) a t^2 we know a, solve for t v = a t
November 3, 2014

Algebra
x = 3 y^3 + 2 y^3 = (x-2)/3 so y = [ (x-2)/3 ]^(1/3) = f-1(x) so [ (x-2)/3 ]^(1/3) = 4 [ (x-2)/3 ] = 64 x - 2 = 192 x = 194
November 3, 2014

algebra
4 q = 5 * 18 2 q = 5 * 9 q = 45/2 = 22 1/2
November 3, 2014

Algebra
1,1 6,7 2,7 2,3 7,9 3,9 3,5 3,1 8,7 4,7 4,3 9,6 5,6 1,6 1,2 6,8 2,8 2,4 7,10 3,10 3,6 3,2 this thing is a pretty good vacuum cleaner, keep going until it repeats a point :)
November 3, 2014

Algebra
if y = x^2 - 2 x f(y) = (x^2-2x)^2 - 2(x^2-2x) = f(f(x)) so x^2-2x = (x^2-2x)^2 - 2(x^2-2x) of course x = zero will do :) let z = x^2 - 2x z = z^2 - 2 z z^2 - 3 z = 0 z (z-3) = 0 so another solution is x^2-2x = 0 = x (x-2 we already have x = 0 so now also have x = 2 and also ...
November 3, 2014

Algebra
I would have said something like that but have been having fun :) She has an imaginative teacher!
November 3, 2014

Algebra
y = (3x-7) / (x+1) inverse x = (3y-7) / (y+1) x y + x = 3 y - 7 3 y - x y = x + 7 y (3 - x) = (x+7) y = -(x+7)/(x-3) f^-1(x) = -(x+7)/(x-3)
November 3, 2014

physics
What you did makes sense to me. I guess we are assuming that the sphere has a very thin wall thickness to get the (2/3) m r^2
November 3, 2014

Math
(5/6 )24 = 20 pennies 20 / 50 = 2/5
November 3, 2014

Math
(2/5 )35 = 14 did not go in piggy bank (1/2) 14 = 7
November 3, 2014

trig actually, or maybe vector trig
4.19 cos 10.4
November 3, 2014

PHYSICS
lol - the other half of the problem 4.19 sin 10.4
November 3, 2014

Physics
emf = N d flux /dt emf = 660 B pi r^2 d/dt (sin 2 pi t/T) when t = .024, t/T = 1/8 T = .192 second so emf = -660 (pi r^2) (2 pi/T)B cos (2 pi t/T) now I do not know what "average means. Obviously the average of a cosine function is zero. You might guess they mean ...
November 3, 2014

Physics 11U
goes up from 2 to 8 or 6 meters do vertical problem v = Vi - g t 0 = Vi - 9.8 t at the top (8meters) so t at top = Vi/9.8 h = 2 + Vi t - 4.9 t^2 at top 8 = 2 + Vi t -(1/2)(9.8) t^2 6 = Vi t -(1/2)(9.8) t^2 6 = Vi^2/9.8 - (1/2) Vi^2/9.8 12 (9.8) = Vi^2 Vi = 10.84 m/s now do the...
November 3, 2014

Math Help!
well, 30 would be 900 and 28 would be 784 so do my proportion thing again 28 x 30 784 872 900 (872 -784)/ (x-28) = (900-784)/(30-28) x-28 = 2*88/116 x = 28 + about 1.5 or around 29.5 so 30 try calculator sqrt (872) = 29.529
November 3, 2014

math
speed = distance/time speed1 = 1020/3.30 speed2 = 1020/2.75 so speed2/speed1 = 1020/2.75 / 1020/3.30 = 3.30/2.75
November 3, 2014

Math Help!
go back and see how I did the earlier one with linear interpolation. It clearly works best when you pick perfect squares above and below the desired answer.
November 3, 2014

Physics
find induced EMF from 193 *area * dB/dt E = (193)pi (5.5*10^-2)^2 (.908) current = i = E/.241 now find B due to i B = mu N i/2 r = 4 pi*10^-7 (193)(i)/(2*5.5*10^-2)
November 3, 2014

Math Help!
15 --> 225 14 --> 196 13 --> 169 12 --> 144
November 3, 2014

Math Help!
x 3 z 4 y 9 14 16 linear interpolate (z - 3)/(14-9) = (4-3)/16-9) z - 3 = (5)(1)/7 z = 3 + 5/7 or a bit over 3.5 so pick 3.7 now use calculator 3.742 :)
November 3, 2014

Physics
(1/2) m v^2 = 182 m v = 27.6 so m = 27.6/v (1/2) (27.6/v) v^2 = 182 (1/2) (27.6) v = 182 etc
November 3, 2014

Help!-algebra
agree, c
November 3, 2014

Math Help!
In other words, Brady is right :)
November 3, 2014

Math Help!
0.8743 8743 8743 8743 * 10^-4 + 8743 * 10^-8 + 8743 * 10^-12 ...... repeating decimal, infinite geometric series a = 8743 r = 10^-4 sum = a/(1-r) = 8743 /(1 - .0001) =8743/.9999 = 87430000 / 9999 which is a rational number being the quotient of two integers/
November 3, 2014

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