Monday
September 22, 2014

Posts by Damon


Total # Posts: 18,625

Algebra
If the difference in x values is constant and the difference in y values is constant then the slope is constant and we have a straight line.
June 28, 2014

Chemistry
1 dm^3 = 1000 cm^3 = 1 liter so X2CO3 is 15.2 g/liter a liter of this requires 27.5/25 or 1.1 liters of .2 M HCl 1.1 * .2 = .22 mols of HCL X2CO3 + 2 HCl --> 2 XCl + H2CO3 maybe? so we only need .11 mols of X2CO3 .11 mols of X2CO3 weigh 15.2 grams 1 mol X2CO3 weighs 138 ...
June 28, 2014

physics
By the way, Newton 2 is force = rate of change of momentum F = m A is the simple version but will not work if mass is not constant (rocket or special relativity for example)
June 28, 2014

physics
Force = rate of change of momentum = m a if mass is constant (7.88 - 8)/.04 = -3 (-5.28+5) /.04 = -7 (0 - 0 ) = 0 so yes m a = .140 (do it in kg) * that a vector
June 28, 2014

physics
Now wait a minute. If friction wins, you do not move it in any direction. Again in number two, imagine. If you caught the ball at the top, the time is all spent getting up. If you tossed the ball off your roof, most of the time would be spent going down. So d) Time to reach ...
June 28, 2014

physics
a = change in v/ change in t = -5/1.4 = -3.57 m/s^2 so F = m a = 6(-3.57) = - 21.4 Newtons The friction force will be larger because proportional to the normal force (eight) F = -21.4 (9/6) = -32.1 Newtons friction force F = m a a = -32.1 / 9 = 3.57 m/s^2 so same time, 1.4 ...
June 28, 2014

Physics
You add the final VERTICAL velocity and the constant horizontal velocity as vectors. You can find the direction with trig if you wish, but the vector components imply direction as well as magnitude. For example V = u i + v j where u is the horizontal velocity component v is ...
June 28, 2014

physics
The vertical velocity is 0 at the top v = Vi - 9.81 t 0 = 5.25 - 9.81 t t = .535 second to the top h = 0 + Vi t - 4.9 t^2 h = 5.25 (.535) - 4.9 (.535^2) h = 1.40 meter alternate and faster way: (1/2) m v^2 = m g h [ conservation of energy ] h = v^2/2g = 5.25^2/19.6 = 1.40 meter
June 28, 2014

Physics
sure If you stand on frictionless ice (good luck), your weight is still held up by the ice.
June 28, 2014

Algebra
multiply by 1.10 every month
June 28, 2014

physics
How long to fall ? 54 = (1/2) g t^2 108 = 9.81 t^2 t = 3.32 seconds in the air, screaming and wishing for parachute In 3.32 seconds we went 130 meters at constant horizontal velocity u 130 = t (3.32) t = 39.2 m/s so now convert that to miles/hr. (Google). 87.7 miles/hr it says
June 28, 2014

physics
260,000 m/h * 1 h /3600 s = 72.2 m/s = Vinitial average speed during deceleration = 72.2 / 2 = 36.1 m/s goes 1500 m at 36.1 m/s 1500/36.1 = 41.5 seconds
June 28, 2014

statistics
3 a Yes, 5/15 = 1/3 3 b just add 5/15 + 3/15 = 8/15 3 c p what are chances of d then a then g ? 5/15 * 7/14 * 3/13 = .03846153 d then g then a ? 5/15 * 3/14 * 7/13 = same etc a then d then g a then g then d g then d then a g then a then d six ways in total, each .03846153 so ...
June 27, 2014

statistics
for 2 use : http://davidmlane.com/hyperstat/z_table.html
June 27, 2014

NEED HELP WITH CALC
Yes, you do ds/dt = -.02 s ds/s = -.02 dt ln s = -.02 t + c e^ln s = s = e^(c-.02t) = e^c e^-.02 t e^c = C any old constant in the general solution s = C e^-.02 t when t = 0, s = Si the initial amount so s/Si = e^-.02 t BUT that is P, the fraction remaining so we have part a b...
June 27, 2014

Algebra
2 sqrt (3) * 4 sqrt (3 * 7) = 8 sqrt (3*3*7) = 8*3 * sqrt (7) = 24 sqrt (7)
June 26, 2014

Physics
I assume you mean approaching FROM south for example, so moving north momentum 1500 * 9 N = 13500 N momentum 700 * 15 E = 10500 E final mass = 1500 + 700 = 2200 2200 v cos (heading ) = 13500 2200 v sin (heading)= 10500 tan heading = 10500/13500 heading = 37.9 degrees east of ...
June 26, 2014

Physics
East 5.9 + 2.4 cos 20 = 8.16 north 2.4 sin 20 + .5 = 1.32 d^2 = 8.16^2 + 1.32^2 tan heading = 8.16/1.32 heading east of north = 80.8 deg or heading north of east = 90-80.8 = 9.19 deg
June 26, 2014

physics
a = change in V/change in time = 40/10 = 4 m/s^2
June 25, 2014

linear algebra
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
June 25, 2014

World Geography
I am very glad Ms Sue answered this because I would have found it necessary to write a book on the subject :) Visions of lateen rigged ships crossing the Indian Ocean from the Spice Islands to East Africa and the Red Sea and caravans trudging overland from the Red Sea to the ...
June 23, 2014

PreCalculus
2x + 2x + x = 200 5x = 200 Pre - Calculus, sure is.
June 23, 2014

Algebra II
f(x+h) = 5/(x+h) f(x) = 5/x [f(x+h) - f(x)]/h = [5x -5(x+h)]/[hx(x+h)] = -5 /[x(x+h) } = -5/(x^2+hx) By the way, if you take the limit of that as h--->0 then you are a calculus student and you just found the derivative d/dx (5/x) = -5/x^2
June 23, 2014

Algebra II
1/(x-a) the domain is all real numbers EXCLUDING x = a where the function is undefined.
June 23, 2014

Suspect typo
I bet it was 0.4 ohm internal resistance.
June 23, 2014

algebra
He is asking the same questions over and over again without trying to do them.
June 22, 2014

algebra
.2 n + 1 n = well, this time it is one of the answers you listed.
June 22, 2014

algebra
4 n + 7 n = now I did the last one, you finish this one. By the way, none of those answers.
June 22, 2014

algebra
7 n - 4 n = 30 3 n = 30 n = 10
June 22, 2014

algebra
-2x + 7x - 2x = -7 + 2
June 22, 2014

Algebra 2
I think you may mean 5^(n-1) try y = 103 * 5^(n-1) when n = 1, y = 103 * 5^0 = 103 when n = 2, y = 103*5^1 = 103*5 when n = 3, y = 103*5^2 = 103*5*5 etc
June 22, 2014

math
originally when n = 0, y = 5 after one month, n = 1 and we should have ten so y = 5 * 2^n after 42 months y = 5 * 2^42
June 22, 2014

Probability
Draw a Venn diagram say we have 100 items 75 are in A or B (25 are outside) 15 are in B 2 of those are also in A (intersection you mean I think) so 13 are exclusively in B That means 75 - 13 = 62 are in A 62/100 = .62
June 22, 2014

Probability
H H H H H H H T H H T T H T T T T T T T
June 22, 2014

Physics
a) No true a) the same as b) but impulse = F dt = delta (mv) F dt = 120 N * 10 s = 1200 N s The change of momentum is M (final velocity - 0) so 1200 N s = M (8 m/s) so M = 150 N s^2/m which is 150 kg note N force =Mass (m/s^2) so N s^2/m = M in kilograms 8 m =
June 21, 2014

first what then what ?
missing input
June 21, 2014

physics
pi r^2 = area = .25 pi = .785 m^2 area * speed = volume/second .785 m^2 * 1.2 m/s = .942 m^3/s times 3600 seconds /hr = 3393 m^3/hr
June 21, 2014

physics
(1/2) rho v^2 = rho g h v = sqrt (2 g h ) = sqrt (2*9.81*1.38) which is exactly what would happen if you just dropped a rock that distance or see http://en.wikipedia.org/wiki/Bernoulli%27s_principle
June 21, 2014

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

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