Thursday

August 21, 2014

August 21, 2014

Total # Posts: 17,955

**physics**

I did #1 #2 potential energy lost = m g h potential energy gained = (1/2) k x^2 for 40 kg 40 * 9.81 * (1+x) = (1/2)(12,000) x^2 solve quadratic for x #3 I have no idea because you did not tell me ratio of bounces
*July 3, 2014*

**ACCOUNTING**

is the sum of your liabilities and ownership equity not your assets? so equity = assets - liabilities
*July 3, 2014*

**chemistry**

P V = n R T T = 16 + 273 V = 10 L = .01 m^3 n of O2 = 51.4/32 n of He = 32.5/4 calculate P of each then add to get total
*July 3, 2014*

**Urgent Calculus Help**

slope is always positive the slope keeps increasing so second derivative is positive
*July 3, 2014*

**Urgent Calculus Help**

Sketch a graph of this function. Then the answers will be obvious.
*July 3, 2014*

**Algebra**

x + (x-6) = 50 2 x - 6 = 50 2 x = 56 x = 28
*July 3, 2014*

**Physics**

m g h is the same small m needs big h Sumo seems to be 20 times as massive as the ball :
*July 3, 2014*

**Physics -- check answers please**

1. ok m g h = 20 * 10 * 2 Joules 2. No. That 400 Joules of potential energy becomes 400 Joules of kinetic energy during the fall. 3. Yes - At maximum stretch the ball stops. The ball is now 2 meters plus x below the starting point where x is the stretch distance down. The ...
*July 3, 2014*

**Social Studies**

NY heeft geen Nederlanders? Ik geloof het niet :)
*July 3, 2014*

**American national government**

separate educational facilities were inherently unequal
*July 3, 2014*

**Physics**

no constant the force increases as the spring stretches F = k x work = k x^2/2 ======================== momentum increases an external force, mg
*July 3, 2014*

**Science**

rot fungus http://en.wikipedia.org/wiki/Wood-decay_fungus
*July 3, 2014*

**Calculus 1**

A = 4 pi r^2 r = D/2 so A = 4 pi D^2/4 = pi D^2 dA/dD = 2 pi D dA/dt = 2 pi dD/dt 1 = 2 pi dD/dt dD/dt = 1/(2pi)
*July 3, 2014*

**arithmetic**

Never buy fish from a farm. Farmed fish is yuucky. Good fish comes from the ocean. lets start with 40 fish the first week 5 die so we have 35 which is 7/8 of original after first week 7/8 or 35 remain then in weeks two and three 3/5* 35 = 21 die so we are left with 35 -21 = 14...
*July 3, 2014*

**Physics (A man in the lift)**

mg down F up mg - F = m a = m g/k mg - jmg = (mg/a)(b+cj) 1-j = (b+cj)/a = 1/k k (1-j) = 1 I do not know what gcd(|a|,|b|,|c|)=1 means so can go no further.
*July 3, 2014*

**us hist**

I was a student in the Netherlands during the Gary Powers U2 incident. Our prestige and President Eisenhower's credibility were terribly damaged even in the Netherlands where the US and Canada were highly respected as the people who came and drove the Germans out.
*July 3, 2014*

**algebra**

6 x^3 - 3 x + 14 x^2 - 7 = 0 3 x (2 x^2 - 1) + 7 (2 x^2-1) = 0 (3x+7)( 2x^2-1) = 0 does that help?
*July 2, 2014*

**Physics**

work in = 44* 13 = 572 Joules which is the increase in kinetic energy
*July 2, 2014*

**Physics**

(a) 208 * 1.91 Joules (b) -154 * 1.91 Joules either add answers to a and b or do (208-154)(1.91)
*July 2, 2014*

**mathematics**

Well, I suppose that is every prime number less than 50 :)
*July 1, 2014*

**Calculus I**

Maybe try this: http://www.youtube.com/watch?v=8CuBoOaiBfA
*June 30, 2014*

**Literature-Help me Ms. Sue**

Yes I agree because then they find out too late
*June 29, 2014*

**Literature-Help me Ms. Sue**

World, warm, wings yes
*June 29, 2014*

**MAT221**

5 y = 8 x + 4 y = (8/5) x + 4/5 so slope is 8/5 so slope of perpendicular is -5/8 form is y = - 5x/8 + b goes through (-4,-4) -4 = -5 (-4)/8 + b b = -4 - 20/8 b = -4 - 5/2 b = -8/2-5/2 = -13/2 so y = - 5 x/8 -13/2 or 8y = -5 x - 52 Now parallel line slope = 8/5 y = 8 x/5 + b -...
*June 29, 2014*

**Physics**

Guess mass of person, say 80 kg guess how many on elevator, say 50 (guess high, we want a strong enough motor) so total mass of people on elevator at one time = 80*50 = 4,000 kg energy change = m g h = 4,000 * 9.8 * 8 = 316,600 Joules divide by 20 seconds ----> 15,688 Watts...
*June 29, 2014*

**Literature-Help me Ms. Sue**

Did you see: " .... I am the grass; I cover all. ..." ?
*June 29, 2014*

**Algebra (Identity Function)**

An identity function returns its argument as its value. x(4) = 4 and y(99) = 99
*June 28, 2014*

**math**

average winning = ( 5+3+2 )/6 = 10/6 net = 10/6 - 2 = -0.33 The house wins, in the end :)
*June 28, 2014*

**Algebra**

quadratic is a parabola with one vertex exponential curves one way like y = e^x curves up sqrt slope becomes smaller and smaller
*June 28, 2014*

**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*

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