Saturday
August 23, 2014

Posts by Damon


Total # Posts: 17,988

physics
77.9 = 10 log I/10^-12 = log I/10^-11 7.79 = log (I*10^12) 10^7.79 = I * 10^12 6.17 * 10^7 = I * 10^12 I = 6.67 * 10^-5 W/m^2
June 21, 2014

EXCEL 2010 (again)
I just tried =sum(C3:C9)/7 and it worked
June 21, 2014

physics
1) do it the same way I did the previous question 1 2) (bottom derivative top - top derivative bottom ) / bottom squared ( x^4 * 0 - 1*4x^3 )/x*8 = - 4 /x^5 3) x^2 cos x - sin x (2x) you finish
June 20, 2014

physics
1) 0 + 5 + 21 x^2 2) tan x (d cos^2 x /dx)+ cos^2 x d tan x / dx = tan x (-2 sin x cos x) + cos^2 x (sec^2 x) = -2 sin^2 x + 1
June 20, 2014

physics
Use parentheses to show what is numerator and what is denominator.
June 20, 2014

Math
1600 grams/3000 grams
June 20, 2014

physics
Hey, I told you how to do these yesterday except number 4 which is incomprehensible without adding parentheses and telling me what is u and what is du. Come on, we are volunteers here. integral x^4 dx = (1/5) x^5 + c integral 1 dx = x + c sum = (1/5) x^5 + x + c
June 20, 2014

PHYSICS
Come to think of it, anywhere at equinox you will have three hours light and three hours dark
June 20, 2014

PHYSICS
angular momentum remains the same. I2 omega 2 = I1 omega 1 I = constant * m R^2 If m2 = m1 and R2 = .5 R1 then m R2^2 = .25 m R1^2 and I2 = (1/4) I1 (1/4)I1 omega2 = I1 omega1 omega2 = 4 omega1 T2 = (1/4) T1 day is 6 hours long instead of 24 so at the equator at equinox we ...
June 20, 2014

maths trigonometry
tan T = 8/7 = sin T/cos T 8 cos T = 7 sin T ----------------------------- (1+cos T)(1-cosT) __________________ (1-sin T) (1+sin T) that is easy 1 - cos^2 T ____________ (1 - sin^2 T) but 1-cos^2 = sin^2 and 1 - sin^2 = cos ^2 so sin^2 T/cos^2 T = tan^2 T = 8^2/7^2 = 64/49
June 20, 2014

math
602234
June 19, 2014

math
987431
June 19, 2014

math
LOL, nah 0.500005
June 19, 2014

Algebra can you give me direction
on your graph paper put a big dot on the point where x = 3 and y = 5 now go right 2 and up 1 to x = 5 and y = 6 in other words(5,6) make another big dot there draw a line of infinite length through the two dots :) if you want the equation then y = m x + b 5 = (1/2)(3) + b
June 19, 2014

Health
http://www.webmd.com/bipolar-disorder/guide/bipolar-2-disorder bipolar 2
June 19, 2014

Chemistry
CaO + CO2 --> CaCO3 atomic masses Ca = 40 O = 16 C = 12 so CaO is 40 + 16 = 56 grams/mol 28/56 = .5 mol so we get .5 mol of CaCO3 CaCO3 = 40 + 12 + 48 = 100 grams/mol so we get 50 grams of CaCO3
June 19, 2014

probability
Binomial distribution p(success) = .9 1-p = .1 P(29 out of 30) = C(30,29) * .9^29 * .1^1 C(30,29) = 30! / [ 1! (29!) ] = 30 so 30 * .9^29 * .1 = .1413
June 19, 2014

physics
1. is integral x^4 dx + integral x dx 2. same deal, split into sum of two integrals integral of cot^2 x = (-1/x)cot x - x 3. yet again cos*sin/cos = cos :) cos * 1/cos = 1 :) 4. I think you have a typo and I do not know what is u and what is du or actually what is in the ...
June 19, 2014

Physics
calculate I of solid disc omegai = 90 rev/min * 2 pi rad/rev * 1 min/60 s = 9.42 radians/second Ke = (1/2) I omegai^2 at start, zero at finish Torque = 4 R = 4*.34 newton meters alpha = Torque/I omega = omegai - alpha t omega = 0 at finish so t = omegai/alpha which is time to ...
June 19, 2014

typo
Huh?
June 18, 2014

Physics
mg = 83.8*9.81 = 822.1 N so Fdown = 822.1-109.1 = 713 a = F/m = 713/83.8 = 8.51 m/s^2 v = a t h = (1/2) a t^2 25 = (1/2)(8.51) (v/8.51)^2 50 (8.51) = v^2 v = 20.6 m/s
June 18, 2014

math
well, if sides are both x and the base is 10 then the perimeter is 2 x + 10 so the sides are x, period, no more can be said. If it were equilateral, then every side would be 10
June 18, 2014

math
sin 20 = w/200 w = 200 sin 20
June 18, 2014

physics
initial momentum = .0165 * 285 change of momentum = -.0165*285 average speed during stop = 285/2 time to stop = .226/average speed during stop Force = change in momentum / time to stop
June 18, 2014

Physics
135 min = 2.3 hr speed = (1/2.3) sqrt (105^2+120^2) km/hr velocity = speed at angle tan^-1(120/105) east of north
June 17, 2014

MATH
well, the easy way is to google Gauss Jordan reduction calculator. http://www.gregthatcher.com/Mathematics/GaussJordan.aspx otherwise do it by elimination First eliminate z from first two: 2x+y-3z = 4 times 2 = 4x+ 2y-6z = 8 4x+0y+2z=10 times 3 = 12x+0y+6z = 30 add the two 16 ...
June 17, 2014

PHYSICS.
a) m g h / t b) answer to a /.35 is power input that times 3.5 is energy input.
June 17, 2014

Functions
Good, you are welcome
June 17, 2014

Functions
180 x - 2 x^2 = A 2 x^2 -180 x = -A x^2 - 90 x = - A/2 x^2 - 90 x + 45^2 = -A/2 + 45^2 (x-45)^2 = -(1/2) (A- 4050) vertex at x = 45 so 45. 45 , 90 area = 4050
June 17, 2014

math
x^2 - 4 = y x^2 - 4 + (4/2)^2 = y + (4/2)^2 (x-2)^2 = y + 4 so vertex at (2,-4)
June 17, 2014

physics
-16 + 3 (30)
June 17, 2014

physics
assuming no friction, gravity does all the work and it is the change in potential energy m g h = 50 * 9.81 * .250 Joules
June 17, 2014

finite math
5/54
June 17, 2014

Maths
.7 x = 21 x = 21/.7 = 30
June 17, 2014

math
.03575/4 = .0089375 per quarter year 30 * 4 = 120 compoundings V = Vi (1.0089375)^120 68,000 = Vi (2.90878 ) Vi = 23,377.45
June 17, 2014

Calculus
I suppose :)
June 17, 2014

Calculus
You have dV/dt = k V and you know that k = -.010526
June 17, 2014

Calculus
sure, in fact I did it with 235 = 240 e^2k
June 17, 2014

Calculus
dV/dt = k V dV/V = k dt ln V = k t + C e^ln V = V definition of ln V = e^(kt + C) C is arbitrary so far V = e^kt * e^C = C e^kt since e^c could be any old C Now that is general solution. Now put in t = 0 at t = 0 e^kt = e^0 = 1 so 240,000 = C e^0 = C so V = 240,000 e^kt Now if...
June 17, 2014

General Physics 1
change in velocity/ change in time = (17.9-29.6) / 4.08 = -2.67 m/s^2 d = Vi t - (1/2) 2.67 * t^2 = 29.6(4.08) - 1.33 (4.08^2) = 121 - 22.1 = 98.9 m
June 16, 2014

math
320 dollars / 40 hours = 8 dollars/hr divide your number line from 0 to 320 up into 40 equal parts.
June 16, 2014

Physics
695 - 135 = 560 N that is the answer you asked for If you also want the acceleration it is a = F/m = 560/18 = 31.1 m/s^2
June 16, 2014

Physics
F = m a a = F/m a' = 3 F /2m = (3/2) F/m (3/2)(2) = 3 m/s^2
June 16, 2014

Calculus
dy / y = 4 e^(5x) dx ln y = (4/5) e^(5x) + c e^ln y = y = e^ [(4/5)e^(5x) +c) y = e^c e^[(4/5)e^(5x) ] y = C e^[(4/5)e^(5x) ]
June 16, 2014

Physics
change in potential energy = m g h = 12 * 9.81 * 15 = 1766 Joules power = joules per second = 1766/3.5 =505 Watts Input power = 505/.15 = 3363 Watts Input energy = 3363 Watts * 15 seconds = 50,451 Joules
June 16, 2014

Physics
assume hydrostatics is negligible F = m a a = 200/70 = 2.86 v = Vi - a t 0 = 10 - 2.86 t t = 3.5 seconds to stop d = Vi t - (1/2)(2.86) t^2 d = 10 (3.5) - 1.43 (3.5)^2 d = 35 - 17.5 d = 17.5 meters well, that is what we get. It is ridiculously high but so be it. Let's hope...
June 16, 2014

Physics
I guess maybe you mean 3.5 kg ??? Force = change in momentum / change in time average speed = (70+0)/2 = 35 m/s so time = .90 /35 = .0257 seconds F = 3.5 * 70 / .0257 = 9528 N
June 16, 2014

physics
loss of gravitational potential energy = m g * change in height = 5 * 9.81 *(2 + .25) = 110 Joules that is now stored in the spring (1/2)kx^2 so (1/2) k (.25)^2 = 110 k = 3532 N/m
June 16, 2014

Math: Trig
Perhaps you were supposed to give both the quadrant 2 and quadrant 2 answers
June 16, 2014

Math: Trig
which is pi +/- pi/3 2 pi/3 or 4 pi/3
June 16, 2014

Math: Trig
sec = 1/cos so what angle has cosine = -1/2 that angle is 180 + or - 60 degrees
June 16, 2014

college physics
Archimedes floats boats !!!
June 16, 2014

physics
I am just plain not going to answer this. Look up what determines the frequency.
June 16, 2014

physics
Jake, what do you think the answer is? Look at pictures of waves on a string. which is the longest wave? Do waves get longer or shorter as the frequency and number of the harmonic go up?
June 16, 2014

physics
When you see a (1/2) rho v^2 in something, which principle do you think of?
June 16, 2014

physics
T = 2 pi sqrt (m/k) 5.5 = 2 pi sqrt (.0029/k) .87535 = sqrt (.0029/k) .766= .0029/k k = .0038 N/m
June 16, 2014

Math
(sqrt3)/2 / 1/sqrt 3 = 3/2
June 16, 2014

Calculus
http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=7c9206fea2b96c1f22626b03b18327b3&title=Math+Help+Boards:+Indefinite+Integral+Calculator&theme=blue says: (x-1)/[7 sqrt(x^2-2x+8) ]
June 16, 2014

Calculus
∫(x2 − 2x + 8)^-1.5 dx
June 16, 2014

Calculus - not sure how but rewrote
I do not know but suspect you mean ∫1/(x^2 − 2x + 8)^(3/2) dx
June 16, 2014

physics
101.5 * 10*3 + 1029 *9.81 * 9.5 = 101.5 * 10^3 + 95.898 * 10^3 = 197 k Pa or about 2 atmospheres note, 30 feet deep is about additional atmosphere
June 15, 2014

physics
x = A sin wt v = A w cos wt a = -A w^2 sin wt = -w^2 x F = m a so -kx = - m w^2 x w^2 = k/m w^2 = k/.0029 w = 18.6 sqrt k when w t = 2 pi, t = T = 5.5 so (18.6 sqrt k) (5.5) = 2 pi sqrt k = .0615 k = .0038
June 15, 2014

physics
x = .084 sin wt max x = .084 when sin w t = 1 then Pe = (1/2) k x^2 = (1/2) 204)(.084)^2 now what is Ke when sin wt = 1? v = .084 w cos wt if sin wt = 1, then cos wt = 0 because sin^2 + cos^2 = 1 always so v = 0 when sin wt = 1 so TOTAL energy = PE at sin wt = 1 = (1/2) (204...
June 15, 2014

physics
x = a sin wt v = a w cos wt a = -a w^2 sin wt = -w^2 x F = m a = -kx when x = 0, equilibrium , sin wt = 0 and cos wt is 1. That is max velocity when w t = pi/2, cos wt = 0 so v = 0 v = a w cos wt which is certainly not constant a = -a w^2 sin wt = -w^2 x which is 0 when x = 0 ...
June 15, 2014

physics
from t = 0 to t = .02 she goes(.21 - .043) = .167 .167 m / .02 seconds = 8.35 m/s
June 15, 2014

english
multiple sclerosis Is the correct spelling I think.
June 14, 2014

PHYSICS
calculate distance 20*2 + 40*2 + 60*6 = calculate time 2+2+6 av speed = distance/time
June 14, 2014

Biomechanics
You exceeded he elastic limit of the material and permanent bending occurred.
June 14, 2014

Algebra
5*4 the rest cancels.
June 13, 2014

Algebra
(x-3)(x+5) well, if x were 4 It could be 9 x 1 or if x were 5 it could be 10 x 2 or if x were 6 it could be 11 x 3 or if x were 7 it could be 12 x 4 etc
June 13, 2014

Science
This question would take all night to answer. I will just make a suggestion or two. Just think about sources. Obviously burning carbon causes CO2 no matter what form the carbon takes (coal, diesel, gasoline, methane ..... ) Some create more problems than others, coal for ...
June 13, 2014

Damon, Still need your help please tho
You are welcome :)
June 13, 2014

Damon, Still need your help please tho
y = k/x 4 = k/6 k = 24 so y = 24/x Just do what it says :)
June 13, 2014

Damon, Still need your help please tho
LOL, many years ago.
June 13, 2014

Damon, Still need your help please tho
I guess C which is 7; where x =/ 2 assuming that x=/2 means not when x = 2
June 13, 2014

Damon, Still need your help please tho
7 where x not equal to 2 (x=2 is not in the domain, function undefined there)
June 13, 2014

Damon, Still need your help please tho
7(x-2) /(x-2) = 7 * 1 = 7 but x may not be 2 or the original denominator would be zero
June 13, 2014

Damon, Still need your help please tho
did the first one already http://www.jiskha.com/display.cgi?id=1402703533#1402703533.1402705078
June 13, 2014

Algebra ll
You are welcome.
June 13, 2014

Algebra ll
x = 3, y = 12 Step 2: Enter the values for your matrix, and press the "Solve" button. Divide row1 by 4 1 -1/2 -3 3 -1 -3 Add (-3 * row1) to row2 1 -1/2 -3 0 1/2 6 Divide row2 by 1/2 1 -1/2 -3 0 1 12 Add (1/2 * row2) to row1 1 0 3 0 1 12
June 13, 2014

Algebra ll
+4 -2 -12 +3 -1 -3 gauss jordan see http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
June 13, 2014

Tricky Math tho (Damon)
Yes, C
June 13, 2014

Tricky Math tho (Damon)
OH !! remainder allowed just do long division 5x - 5 with remainder of 3 so 5x - 5 and 3/(5x-3)
June 13, 2014

Tricky Math tho (Damon)
try factoring the top. If this problem is possible, a factor is (5x-3) (5x-3)( 5x +or-6 to get 18) (5x-3)(5x-6) hey are you sure it was not 25 x^2 -45 x + 18 ?????
June 13, 2014

Almost done with this math tho
It is 7 but there is no solution if x = 2 (undefined, zero denominator, not in domain)
June 13, 2014

Almost done with this math tho
7(x-2) / (x-2) = ?
June 13, 2014

Algebra
do you mean 1/x + 1/(x+5) + 1/(3x) = 100/225 ???? 225/x +225/(x+5) + 75/(x) = 100 300/x + 225/(x+5) = 100 (x+5)(300) + 225 x = 100x(x+5) 300 x + 1500 + 225 x = 100 x^2 + 500 x 100 x^2 -25 x -1500 = 0 20 x^2 - 5 x - 300 = 0 4 x^2 - x - 60 = 0 (x-4)(x+15) = x = 4 or x = -3.75
June 13, 2014

this math tho (Damon or Steve)
30 = 5 * 2 * 3 all prime numbers so sqrt (30) is sqrt (30) period however sqrt on the bottom is no fun, should rationalize multiply top and bottom by sqrt 30 (5/sqrt30)(sqrt30/sqrt30) = (5 sqrt 30) /30 = sqrt (30) /6
June 13, 2014

this math tho
You are welcome :) No thinking, just doing and CHECKING
June 13, 2014

this math tho
x^2 - 6 x + (6/2)^2 = 7 + (6/2)^2 x^2 - 6 x + 9 = 7 + 9 (x-3)^2 = 16 (x-3) = 4 or (x-3) = -4 x = 7 or x = -1 check 1 + 6 = 7 49 - 42 = 7
June 13, 2014

Another this math tho
2 * 1 = 2 b^-6 * b^12 = b^(-6+12) = b^6 so yes, 2 b^6
June 13, 2014

this math tho
well, first of all, check your answer back in the originl for example if x = 8 3 (8-4) + 54 = -3(8) ???? 12 + 54 = -24 I doubt it Now let me try 3 x - 12 + 54 = -3 x 6 x + 42 = 0 x = -42/6 = -7 now check that back in the original
June 13, 2014

ALGERBRA
that comes out to: .0004952 or use combinations 13 hearts in deck number of combinations of 5 in 13 = c(13,5) = 13!/[ 5!(8!) ] = 1,287 5 in 52 = 52!/[5!(47!)] = 2,598,960 quotient = .0004952
June 13, 2014

ALGERBRA
first card 1/4 second card 12/51 third card 11/50 fourth card 10/49 fifth card 9/48 multiply :)
June 13, 2014

math
You are welco0me. Just remember to reverse arrow when multiplying (or dividing) by negative quantity
June 13, 2014

math
14 < -2x 7 < -x or -7 > x reverse arrow when multiplying by negative quantity or x <-7 check that, for example if x = -8 14 + 7x = 14 - 56 = -42 5 x = -40 so yes, 14 + 7x < 5x
June 13, 2014

Financial Math
2500 * (1.03^6) = 2985.13 now 2985.13 (1+ .05/12)^24 = 3298.39 3298.39 -2500 = 798.39
June 13, 2014

English
5 is the only one that sounds right to me.
June 13, 2014

algebra
look at that second equation. You can easily solve it for y namely y = 2x-1 so use (2x-1) for y in the first equation 3 x - 4(2x-1) = 5 3 x - 8 x + 4 = 5 -5 x = 1 x = -1/5 then y = -2/5 -1 = -7/5 check that -3/5 +28/5 = 25/5 = 5 yes, checks -2/5 + 7/5 = 5/5 = 1, yes, so we ...
June 13, 2014

algebra
x = 3 , y = 2 is the intersection
June 13, 2014

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