Friday
August 26, 2016

Posts by Damon

Total # Posts: 26,794

please use one name
ah come on
July 30, 2016

Calculus AB
5, 12, 13 right triangle here so sec = 1/cos = 13/5 then 3, 4 , 5 tan = 1/cot = 4/3 so sin = 4/5 so 13/5 - 4/5 = 9/5
July 30, 2016

Calculus AB
h = ln (sin x) look at this at x = 0, x = pi/2, x = pi/4, x = 3 pi/4 , x = pi , note sin x must be >0 so only quadrants 1 and 2 ln sin 0 undefined ! ln sin pi/4 = -.346 ln sin pi/2 = 0 ln sin 3 pi/4 = -.346 etc :)
July 30, 2016

Calculus AB
y = a cos (k x - b) + c a and c are easy because c is average of 8 and -2 or 3 and a is thus 5 y = 5 cos (k x - b) + 3 cos is max of 1 at k x - b = 0 k*3-b = 0 so b = 3 k so y = 5 cos (k x - 3 k) + 3 cos is min of -1 at k x - b = pi kx - 3k = pi but x = 7 here so 7 k - 3 k = ...
July 30, 2016

English
a piece of ONE banana well, again ONE banana or just the singular type of fruit again not two apples but two pieces of apple
July 30, 2016

Math
if 4 t = 2 pi t = pi/2 if 6 t = 2 pi t = pi/3 so we need at least t = 0 to t = pi/2 or any other interval of length pi/2
July 30, 2016

Math typo
t = -1 + 5 t ? I doubt it then 1 = 4 t and t = 1/4 x = 2 - 3 (1/4) period
July 30, 2016

Physics
average force = change of momentum/time
July 30, 2016

Physics
NEWTON'S FIRST LAW !!!! 75 * 5 = (75+40) * v
July 30, 2016

Physics
mu static = friction force/normal force = 300/400 similarly mu dynamic = 200/400 Why are you asking questions that I am sure are covered in your text?
July 30, 2016

maths
ten sides? going around the outside we have to turn right ten times that means each time we turn right 36 degrees which is 360/10 that means the interior angle= 180 - 36 = 144 degrees in radians this is pi - 2pi/10 = 5 pi/5 - pi/5 = 4 pi/5
July 30, 2016

statistics
We need the sum of probabilities of 6, 7 and 8 This is much more advanced than your previous questions and requires use of the binomial distribution rules. P(x=k) = C(n,k) p^k p^(n-k) where C(n,k)=n!/[k!(n-k)!] so for example the P(x=6) is P(x=6)= C(8,6) .33^6 * .67^2 where C(...
July 30, 2016

math
b is bigger than a and smaller than c
July 29, 2016

statics is not statistics
....and statistics is not statics * | 1 2 3 4 5 6 _______________ 1 | 2 3 4 5 2 | 3 4 5 3 | 4 5 4 | 5 5 | 6 | so 10/36
July 29, 2016

statics
.....and you mean statistics :)
July 29, 2016

statics
I did NOT say 28 I said 28 divided by the sum
July 29, 2016

statics
You mean statistics by the way. I replied because I do statics and dynamics. It is just luck I knew the probability question answer.
July 29, 2016

statics
sum = 33 + 34 + 30 + 28 answer = 28 / sum
July 29, 2016

statistic
recipe is here: http://davidmlane.com/hyperstat/z_table.html
July 29, 2016

physics
d = .05 meter Fx = k [Q^2/.05^2]cos 30 from each Fy cancels so it is just 2Fx (repels of course because same sign)
July 29, 2016

general solution
Call the time, which I think is a typo, T distance is d t1 = time out t2 = time back t1 + t2 = T t1 = d/55 t2 = d/330 so d/55 + d/330 = T d = T /(1/55 + 1/330)
July 29, 2016

too long a time
7 seconds?
July 29, 2016

math
Trick question (1/cos A)(cos A) = 1 unless cos A = 0 but what is cos 90 ? If A = 90. in fact the secant is just plain not defined. http://socratic.org/questions/what-is-the-exact-value-of-sec-90
July 29, 2016

probability
Consider these events independent because there are a lot more than 4 children in Ghana. Use binomial distribution. C(4,4)(.65)^4 (.35)^0 1 * .65^4 * 1 .65^4 note C(n,k) = n!/[k!(n-k)!] defined as 1 for k = 0 see http://www.mathsisfun.com/data/binomial-distribution.html
July 29, 2016

Stats
http://www.google.com/search?q=david+m+lane+normal+curve&ie=utf-8&oe=utf-8
July 29, 2016

Chemistry
C2D3 has a solubility product constant of 9.14×10−9. What is the molar solubility of C2D3? Express your answer with the appropriate units.
July 28, 2016

Math
92 + 64 - (73+89) - (66-49) etc down to -42-(-81)-(-73)=? = -42 + 81 + 73
July 28, 2016

makes no sense
how much time? how many km, whatever?
July 28, 2016

math
One faucet fills 100 gal in 18 min so a faucet does (50/9) gal/min 6 *(50/9) t = 25 6*(2/9)t = 1 t = 9/12 = 3/4 minute
July 28, 2016

math
2016 - 2000 = 16 16 * 7 = 112 224 - 112 = 112 half the original
July 28, 2016

mathematics
x(g+b) have not finished .65 g have not finished .55 b have not finished .65 g + .55 b = x(g+b) but g = 3 b so .65(3 b)+.55 b = x ( 4 b ) (1.95+.55)b = 4 x b x = 2.5/4 = .625 so 62.5 %
July 28, 2016

world history
First of all, who says? Although the habit is to treat Chinese dynasties as succeeding, there is no reason they should not have overlapped. That said, they had, as the Chinese always had, nomadic tribes to the north and west and the bleak ocean to the east. Mostly mountains ...
July 27, 2016

science(physics)
momentum = 0.100 * 20 = 2 kg m/s distance into plank = .020 meter average speed in plank = 20/2 = 10 m/s time in plank = .020/10 = .002 s average force = change in momentum/time = 2/.002 = 1000 Newtons
July 27, 2016

math
(9/36)*900 = 900/4 = 225
July 26, 2016

Math
This is not a submarine but a research submersible. Submarines do not go much deeper than a couple of boat lengths. 8 * 60 + 37 = 517 seconds 517 seconds * 25 ft/s = 12,925 feet Although that is far deeper than a submarine dives, it is less than half as deep as the Mariana ...
July 26, 2016

Chemistry
How much H3PO4 is needed to neutralize 1 liter of a 0.75M solution of NaOH? (in moles)
July 26, 2016

Math
8 sin 30 + 8 sin 120 8 (1/2) + 8 (1/2) sqrt 3
July 26, 2016

math
must be combined age? p = 2 j p-17 + j-17 = 33 p + j = 67 2 j + j = 67 3 j = 67 j = 67/3 = 22 1/3 so p = 134/3 = 44 2/3
July 26, 2016

physics
h = Hi + Vi t - 4.9 t^2 v = Vi - 9.81 t when is v = 0 ? (the top) t = 30/9.81 = 3.06 seconds coasting up to a stop so h = 50 + 30 (3.06) - 4.9 (3.06)^2
July 26, 2016

Physics
You kidding? 200 - 3(45)
July 26, 2016

physics
v = Vi - 9.81 t h = Hi + Vi t - 4.9 t^2 42 = 0 + Vi(2) - 4.9(4) Vi = 30.8 meters/ second when it hits ground, v = -30.8 m/s v = Vi - 9.81 t -30.8 = 30.8 - 9.81 t t = 6.28 seconds
July 25, 2016

Chemistry
Thank you so much!
July 25, 2016

Chemistry
What volume of nitrogen dioxide (in L) is produced from the complete reaction of 16.87 of lead (ii) nitrate at STP
July 25, 2016

college physics
time for one wave = period = 1/f = 10/30 so f = 3 Hz
July 25, 2016

physics
u = 10 m/s forever v = -gt = -9.81 (3) = - 29.4 m/s check if it hit the ground d = (1/2) g t^2 = 4.9 * 9 = 44.1 so still in the air speed = sqrt (10^2 + 29.4^2)
July 25, 2016

Maths
a + 20 = 3 (180-a) a + 20 = 540 - 3 a 4 a = 520 a = 130 180-a = 50
July 25, 2016

Maths
(n + m)/2 = 15 so n + m = 30 m = (30-n) (n m )^.5= 9 n m = 81 n(30-n) = 81 -n^2 + 30 n = 81 n^2 -30 + 81 = 0 (n-3)(n-27) = 0 3 and 27
July 25, 2016

General Mathematics
http://www.jiskha.com/display.cgi?id=1469428320
July 25, 2016

Maths
7 +8 +3 = 18 so 2 are white 2/20 = 0.1
July 25, 2016

huh? typos?
maybe 2 meters deep and find volume not height? if so v = w L d = 20 *100 *2 = 4,000 m^3
July 25, 2016

Math (Rational Inequality)
x^2 h = 8 x = sqrt(8/h) if h = x x = h = 2 if x > h, not allowed if x < h then h > 2 so x < 2
July 25, 2016

algebra
Well, you know 48 = 16*3 You know that 3/3 = 1 so multiply 3/16 by 3/3 and get 9/48
July 25, 2016

ststistics
binomial distribution p = .24 1-p = .76 n = 10 P(2) = C(10,2).24^2 (.76^8) but C(10,2) = 45 so 45 * .0576 * .111 = .288 P(1) = 10 * .24 * .76^9 = .203 so answer to b is 1 - .288 - .203 c is same way but boring. you do it
July 25, 2016

Hey wait a minute
This is very, very similar to one I already helped you with. Please try them yourself. It does not do you any good to have us do all the problems for you. The idea is that we can help, but not do virtually the same problem over and over for you. http://www.jiskha.com/display....
July 24, 2016

MATH
let x = tan t then dx = sec^2 t dt sec^2 t dt/[ tan t (1+tan^2 t) ] NOTE: 1+tan^2 t = sec^2 t !!! wow that helps :) so we have dt/tan t = ctn t dt = ln (sin u)
July 24, 2016

Math
u = 1 - y^2 du = -2 y dy or dy = du/-2y ((y^3)/(u^2))[du/-2y] (-1/2)y^2 du/u^2 but y^2 = 1-u so -(1/2)(1-u) du/u^2 = (u/2)du/u^2 - (1/2)du/u^2 = (1/2) du/u - .5 u^-2 du finish and check my arithmetic :)
July 24, 2016

Someone Please Help me- PreCalc
x^2 + y^2 = 1 16/49 + y^2 = 49/49 y^2 = 33/49 y = +/- sqrt (33) /7 so since in Q IV where y is negative (4/7, -sqrt(33)/7 )
July 24, 2016

physics
10 * 100
July 24, 2016

physics
potential energy at top = kinetic energy at bottom m g h = (1/2) m v^2
July 24, 2016

maths
24 + 5 - 17
July 24, 2016

Physics
Oh, do cos wt = -1/2 as well
July 24, 2016

Physics
x = X sin w t v = X w cos w t so X w cos w t = (1/2) X w cos w t = 1/2 w t = 60 degrees, 300 degrees etc or in radians pi/3 etc so what is x/X when wt = pi/3 etc x/X = sin wt x/X = sin 60, 300 etc x/X = .866 , -.866 etc
July 24, 2016

Math
x + 24 = 36 ?? -24 = -24 ---------------add x + 0 = 12 so x = 12
July 23, 2016

Math
.3(10) = 3 .3(10+10) = 3+3 = 6 .3(10+10+10) = 3+3+3= 9
July 23, 2016

physic
kinetic energy = (1/2) m v^2 that goes into heating the brakes (use Joules not calories) energy =specific heat*mass*(Tend-Tbegin)
July 23, 2016

Science
(1/2) m v^2 = (1/2)(1/2)(9) = 9/4 Joules
July 22, 2016

math
first blue: 6/16 second blue 5/15 so 3/8 * 1/3 = 1/8 = 0.125
July 22, 2016

math whoops 4/13
sorry, 4/13
July 22, 2016

math
careful !
July 22, 2016

math 11/36
http://davidmlane.com/hyperstat/A136602.html
July 22, 2016

math
Yes,note unlike the other two questions because red and spade are mutually exclusive
July 22, 2016

physicis
metal A length x metal B length (15-x) x(4.3)(pi r^2) + (15-x)(6.3)(pi r^2) = 21757 4.3 x + 94.3 - 6.3 x = 21757/(81 pi) 2 x = 8.8 x = 4.4 cm
July 22, 2016

Physics
m = 670/g = 670/9.81 = 68.3 kg F = G m Ms/(r^2) F=6.67*10^-11*68.3*1.99*10^30/7500^2
July 22, 2016

stats
http://davidmlane.com/hyperstat/z_table.html
July 22, 2016

PHYSICS
well, I am just going to estimate iron density about 8 times water 8000 kg/m^3 or 8 g/cm^3 8 L pi r^2 = 8(85)(3)(2.5)^2 about 8 * 85 *3 * 6.3 or 12852 grams 12.8 kg no problem :) less than 30 pounds
July 22, 2016

maths
n cupcskes n/6 to neighbor , 5n/6 remain (7/10)(5n/6) to sister or 7n/12 to sister (3/10)(5n/6) remain or n/4 remain so n/4 =12 n =48
July 22, 2016

Physics
How high does it go? v = Vi -9.81 t at top v = 0 0 = 14 -9.81 t so t = 14/9.81 then h = 100 + 14 t - 4.9 t^2 now fall from h v^2 = 2 g h
July 22, 2016

Algebra
x and (60-x) 2 x -.5(60-x) = 10 2 x -30 +.5 x = 10 2.5 x = 40 25 x =400 x = 16 60-x = 44
July 22, 2016

Algebra
(y-a)^2 = y^2 - 7 y + p y^2 - 2 a + a^2 = y^2 - 7 y + p 2 a = 7 a = 7/2 so p = a^2 = 49/4
July 22, 2016

Physics,Mthe
mass/volume = density =100/10 = 10 but you have given no units so it could be anything at all.
July 22, 2016

math
96
July 21, 2016

math
64
July 21, 2016

math
32
July 21, 2016

Physics
I am not going to just give you the answers to these very basic questions. Try yourself and maybe someone will help if you get messed up.
July 21, 2016

No way !
No, I refuse to just answer. You say and tell us why. What do you think? What is the difference between mass and weight? Would it be different at different locations in the body?
July 21, 2016

American History
Budgets cuts in our Defense has led to inefficient weapons available to the soldiers to fight wars here in America or Overseas. ??????????????????? Please compare US defense budgets and resulting weaponry to those of other countries.
July 21, 2016

Math
For what value(s) of r is r^2+5r+6/r+2 equal to 0? A) -2 only B) -3 only C) 3 only D)-2 or -3 E) 2 or 3 I got A but it is incorrect and I'm still confused Thanks
July 20, 2016

Chemistry
How many grams of hydrogen peroxide (H2O2) must be added to 1,500 ml of water to produce a concentration of 1.33 m (molal solution)?
July 20, 2016

Math
checks at http://www.mortgagecalculator.org/
July 20, 2016

Math
payment = principal [ r/ (1 - {1+r}^-n) ] here principal = 200,000 r = .10/12 = .0083333333..... n = 25*12 = 300 = 200,000 [ .00833... / (1-{1.00833..}^-300) ] = 200,000 [ .009087 ] = 1817.40
July 20, 2016

math
7 * 9 = 63 315/63 = 5 so 7 * 9 * 5 = 315
July 20, 2016

Geometry
y = 2 x - 5 to y = 2 x moves up 5
July 20, 2016

Math
have played x have won .75 x will have won .75 x + 4 will have played x + 4 so .75 x + 4 = .80 (x +4) 4 - .8*4 = .05 x 4 - 3.2 = .05 x .8 = .05 x 800 = 5 x x = 160
July 20, 2016

Algebra
c^2 + 18 c - 175 = 0 (c + 25)(c - 7) = 0 c = 7 or c = -25
July 20, 2016

statistics
15951/13 = 1227 per yesr
July 20, 2016

Math
7 1/2 = 15/2 15/2 / 3/4 = 30/3 = 10 =============== or 10 * 3/4 = 30/4 = 7 1/2
July 20, 2016

algebra
Well, if the denominator is constant and x is alone up there (no x^2 or sin x or anything) then yes
July 19, 2016

Northwest is not 30 deg n of e
when you get the geometry figured out look at: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/forwir2.html
July 19, 2016

Nobody knows
we do not know what the dimensions were on the plans, or alternately the area. If you know the area on the plan, A in^2 then Areal = A (9 ft^2/6.25 in^2)
July 19, 2016

physics
Well, you could use Maxwell's equations, but it might be easier to make a common sense guess. If moving the magnet makes a voltage, then it is likely that moving it faster will make a bigger voltage.
July 19, 2016

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