Tuesday

July 29, 2014

July 29, 2014

Total # Posts: 17,557

**math**

200 * 1/3 is one way

**math**

9/16 or anything else greater than 1/2 and less than 1

**AP Calculus**

I assumed circumscribed meant outside, but it is unclear indeed.

**AP Calculus**

sketch the graph of e^x with the rectangles of height e^2, e^4 and e^6 and base of 2 each 2 e^2 + 2 e^4 + 2 e^6 = 2 (e^2 + e^4 + e^6)

**physical science**

Period = 1/f = (1/5.3)10^-14 seconds distance = speed * time lambda = 3*10^8 m/s * (1/5.3)* 10^-14 = .566 * 10^-6 meters = 566 * 10^-9 meters 10^-9 meters is nanometers, usually used for visible light wavelength

**physics**

P = angular momentum = I omega I1 = (1/2) m r^2 = (1/2)(4.7)(.17)^2 = .0679 P1 = (.0679) 2 pi (1.8) I2 = I1 + (1/2)(3.1) (.065)^2 = .0679 + .00655 = .0744 P2 = P1 so .0744 (2 pi)(rps) = .0679 * 2 pi *1.8 rps = 1.64 revs/s so I agree with you wholeheartedly

**Physics**

You are welcome :)

**Physics**

short string ----> higher frequency !!! f = k/L so (5/4) 440 = 550

**English**

Not Thanks but Satire :)

**math**

P = R - C P = 4 x - 2 x - 20 P = 2 x - 20 for 0 profit, x = 10

**math**

y = 5(1/x) is inverse 5 is the constant You only gave me one relationship.

**Physical Science**

This is the trouble with OTEC (Offshore Thermal Energy Conversion) where the difference in temperature between deep ocean water and water at the surface (in tropics of course) can be used to run a turbine system and generate electricity or whatever. However the efficiency is l...

**Physical Science**

if you mix hot and cold water and get warm water the entropy is higher, even if the energy did not change. The availability of that energy is what changed. Between a glass of hot water and a glass of cold water you can run an engine. However there is not much you can do with a...

**Physical Science**

increase

**Physical Science**

greater than Carnot cycle 1 - (Tcold/Thot) T in KELVIN (dge C + 273)

**Physical Science**

P V = n R T well, R does not change :) R = P V/(nT) = P' .5V /(.5n 2T) = P'(.5)V/(nT) so .5 P' = P P' = 2 P

**Physical Science**

Heat out = Specific heat of ice * mass of ice * change in temp

**Physical Science**

heat out = specific heat of water * mass of water * (30-0)

**Physical Science**

go boom !

**Physical Science**

heat in = SH * m * delta T SH = heat in / ( m* delta T)

**Physics**

F = k Q1 Q2 / d^2 = 9*10^9 * 1.6*10^-19*1.6*10^-19 / (26.1*10^-30) = .882 * 10^1 = 8.82 Newtons

**Dynamics**

m = 20*10^6 g = 20*10^3 kg v = 8000m/3600 s = 2.22 m/s Ke = (1/2) m v^2 = 10*10^3 * 4.94 = 4.94 * 10^4 Joules = (1/2) k x^2 x = .4 meter (wow!) x^2 = .16 (1/2) x^2 = .08 so k = 4.94 * 10^4/.08 =61.7 *10^4 N/m = 617,000 N/m

**Physics**

http://www.jiskha.com/display.cgi?id=1395061565

**Physics**

I did this already.

**Math plz help me!!! URGENT!!**

You are welcome.

**Math plz help me!!! URGENT!!**

(1/3) pi r^2 h = (1/3)(3.14) (100)(6) =628 mm^3 pi r L = 3.14 * 7 * 13 = 286

**Calc**

what is x is negative or zero Tim ?

**Calculus Help Please!!!**

I figured the same but he said specifically that a was variable.

**Calculus Help Please!!!**

2 y dy/dx = 2 x + 2 a da/dx y dy/dx = (x+a da/dx) dy/dx = (x + a da/dx)/y or dy/dx = (x + a da/dx)/(x^2+a^2)^.5 --------------------------------- 2 y dy/dx + a dy/dx + y da/dx = 2 x^2 + a + x da/dx + 2 a da/dx (2y+a)dy/dx = 2 x^2 +a +(x-y+2a)da/dx dy/dx = [2 x^2 +a +(x-y+2a)da...

**Physical Science 9**

2 H2O ----> 2 H2 + O2 That is a reaction in the outer valence electron shells so despite being a physicist, I call it chemical.

**physics**

initial momentum = 28000 u final momentum = (m+28000) v so 28000 u = m v + 28000 v initial ke = 14000 u^2 final ke = (14000+.5m)v^2 (14000+.5m)v^2 = .8 (14000 u^2) (14000+.5m)v^2= 11200 u^2 so I have these two equations to work with: 28000 u = m v + 28000 v and 11200 u^2 = (14...

**Physics**

r = .14 meter w = omega, angular rate in radians/sec Ac = w^2 r F = m Ac 4*10^-11 = 3 *10^-16 (w^2)(.14) w^2 = 9.52 * 10^5 = 95.2 * 10^4 w = 9.76 * 10^2 radians/second rev = 2 pi radians 976 rad/s * 1 rev/2pi rad = 155 rev/s

**algebra**

- (-3)^2 - 5 (-3) + 6 - 9 + 15 + 6 21 - 9 12 your turn

**algebra**

You try first. Remember anything at all to the 0 power is ONE.

**Physical Science 9**

mass heat in = specific heat * mass * temperature rise

**Physical Science 9**

a compound

**Physical Science 9**

Pressure. When you reduce the pressure over a liquid surface to below vapor pressure, it boils off. If you increase the pressure, it does not boil until a higher temperature (eg - pressure cooker). The pressure is high enough in the can to hold the contents in a liquid state, ...

**math**

can vol = pi r^2 (10) = (22/7)(3.5)^2(10) = 385 cm^3 pan vol = 20*9*14 = 2520 cm^3 2520/385 = six and a half

**cal**

fx = 3 x^2 + 4 y level if x = +/-(4y/3)^.5 fxx = 6 x fxy = 4 fy = 4 x - 4 y level when x = y fyy = -4 fyx = 4 extreme only when x = y = 0 H matrix 6 x 4 4 -4 det = -6x - 4 if x = 0, det = -4 if det <0 then (0,0) is a "saddle point"

**math**

x^2 y = 2009 I fooled around factoring 2009 and the only square I found that was a factor was 49 49 * 41 = 2009 so 7 * 7 * 41 = 2009 so I have 2 faces that are 7*7 or 49+49 = 98 stickers then I have fours faces that are 7*41 so 4*7*41 = 1148 1148 + 98 = 1246 stickers used 2009...

**Physics - Current ????**

There is no current specified so row straight across :)

**Physics ?**

Why would I need a torque to move straight? why would I need any force to move at constant velocity? I am wondering who assigned this question.

**Math**

width = x length = y kitchen is 10 by x dining room is square so (y-10) = x kitchen area = 10 x dining area = x^2 so 10 x + x^2 = 264 x^2 + 10 x - 264 = 0 (x-12)(x+22) = 0 x = 12 y = x+10 = 22 so living room is 12 by 12 length is 22

**Calc**

I want a line perpendicular to that line that passes through the point. (There are quick formulas for this but I do not remember them) the line in slope intercept form: 2 y = 2 x + 3 m = 2/2 = 1 so slope of out perpendicular is -1/1 = -1 so y = - x + b goes through (-4,-4) -4 ...

**Linear Algebra**

1 4 0

**Linear Algebra**

1 4 2 17 3 1 -5 7 2 -3 -7 -10

**Linear Algebra**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

**Probability**

prob first one walked, second did not = (18/50) (32/49) = .235 prob second one walked, first did not is the same so .235 * 2 = .47

**Probability**

18 of the 50 walked probability that the first one walked = 18/50 now you pick a second out of a population of 49 of whom 17 walked so 18/50 * 17/49 = 306/2450 = .125

**I really need help**

You are welcome, good luck :)

**I really need help**

5 * 7 * 3 =

**I really need help**

area of one side of pyramid = (1/2)(11)(15) = 82.5 cm^2 so area of 4 sides = 330 cm^2 but we also have the area of the bottom which is 11*11 = 121 cm^2 so total = 451 cm^2

**I really need help**

anything with straight sides and a pointed top has volume = (1/3)base area * height here base area = pi r^2 = 314.159 so vol = (1/3)(314.159)(6) = 628.31 mm^3

**Pre-Calculus**

OIC, ok r = sqrt (25 + 144) = sqrt (169 ) = 13 angle in quadrant 4 tan angle below x axis = 12/5 angle below x axis = 67.4 degrees or 360 - 67.4 = 292.6 degrees

**Huh ??**

usually they are of form: a i +/- b j

**Pre-Calculus**

e^i theta = cos theta + i sin theta so 9 e^i(3 pi/2) ----------------- 3 e^i(pi/4) = 3 e^i(5 pi/4) = 3 [cos (5 pi/4) + i sin (5 pi/4)] = 3 (-.707) + 3i(-.707) or -(3/2) sqrt 2 - (3/2) i sqrt 2

**Pre-Calculus**

cos pi/3 = 1/2 sin pi/3 = sqrt 3/2 so x = 3/2 and y = (3/2)sqrt 2

**Pre Calculus**

2 e^i(pi/6) * 4 e^i(4pi/6) = 8 e^i(5 pi/6) = 8 [cos (5 pi/6) + i sin (5 pi/6)] 150 degrees , quadrant 2 , 30 above -x axis 8 [ -sqrt3/2) + i (1/2) ] -4 sqrt 3 + 4 i

**Physics**

well, you must have found the east and south speeds to get the angle from tan angle = speed south/speed east then Vf = sqrt (Vsouth^2 + Veast^2)

**Money**

No, but I could 86/102 = x/100 x = 100 (86/102)

**Money**

86 = x(102) x = 86/102 = .842 100 x = percent = 84.2 %

**Math**

employees earns x manager earns 1.4 x x/1.4 x = 1/1.4 = 10/14 = 5/7

**Science**

You are welcome :)

**Science**

That seems reasonable. See for example: http://www.britannica.com/EBchecked/topic/967311/nitrogen-fixing-bacteria

**prison effectiveness research question**

If you are specific about what sort of teacher you need you do not have to waste the time of mathematicians and other wandering souls.

**algebra**

That is interesting but not particularly useful. Do you have another line to go with it so we can see where the cross?

**chemistry 101**

PBr3 is 271 grams per Mol Br is 80 g /mol so Br3 is 240 g/mol (240/271)1.57 = 1.39 grams

**Huh?**

You can not find the forces or acceleration without more information. The only thing you can use is the First Law, conservation of momentum, which will give you final speed if they stick together. (1/3 the original speed) To answer questions about force and acceleration, you m...

**Calculus**

You can see that tangent from (0,3), the top of the ellipse, to (12,3) is y = 3 by inspection. The other tangent requires some work :)

**Physics**

I suspect Flove is in Newtons, not in meters integral F dx from 0 to 2.6 (2/3) x^3 + (3/4) x^4 zero at 0 so just evaluate for x = 2.6 11.71 + 34.27 = 46 Newtons

**statistic**

a. 1/4 b. 4/52 = 1/13 c. 1/52 d. 13 clubs including jack and 3 other jacks = 16/52 e. 16 face cards , 4 are Jacks 4/16 = 1/4 f if we know we got a heart, it is red 13/13 = 1

**math**

well first a typical common denominator example find a common denominator to compare 1/3 and 2/5 the denominator will have to have a 3 in it and a five in it In this simple case 3*5 = 15 will work Now find something over 15 that is the same as 1/3 multiply top and bottom by fi...

**What is the question ?**

If both are true, then ay = ax and therefore y = x

**algebra**

x = year -1940 if x = 0 , y = 23,800 if x = 60, y = 113,100 slope = m = (113,100 - 23,800)/60 y = 1488.33 x +23,800 when year = 2040 x = 2040 - 1940 = 100 years y = 1488.33 (100) + 23800 = 172,633 so the last one

**Physics**

height = x sin theta potential energy = m g h = m g x sin theta assuming x is zero at the bottom and positive up ramp potential energy + kinetic energy = total energy = constant if ignoring friction potential = m g x sin theta kinetic = (1/2) m v^2 sum is constant so as x get...

**science pls help**

This is all the same question, Newton's second law. Force = mass * acceleration THINK !!!

**Math**

sum of 1 + 3 + 9 + 27 ..... 3^(n-1) geometric series a = 1 r = 3

**physics**

distance flown if level = d tan 78.6 = 5900/d d = 1190 meters in ten seconds so 119 meters/second

**Social studies check answers ***damon*****

largest cities ? Look at map, coastlines I would say A for the second one. Look at Brazil and Argentina and Columbia. The joke is that Peruvians descend from the Incas but Argentinians descend from the boat :)

**math**

8+8+8+8+8+8+8+8 = 64

**science URGENT so need help**

F = m a

**Needs plant biologist**

Hey, my degree is in Physics :)

**math**

yes yes assuming only one of them is white which is implied by the grammar.

**Dividing Polynomial**

2. yes 3 x^2 + 2 x + 3 R = -2

**Dividing Polynomial**

1. yes 5 x^2 - 4 x + 4 R = -11

**math**

2*6*6 ?

**not sure Writeteacher**

I do not know of anyone here who can help off hand. I think Jenny had best ask at the University of Chicago :)

**OK, I did it**

http://www.jiskha.com/display.cgi?id=1394740694#1394740694.1394743546

**please check(Social studies)**

I would not have thought of that answer but I would certainly include it. I would also include specifics such as trade connection between Byzantine Empire and the Vikings (I say that because it is very important in the news right now but no one knows that except historians and...

**Science**

Hey, go Google Periodic table. Table was invented before protons and electron valence effects were known about. It is D historically.

**math**

yes. 1/10 for breakfast bars

**math**

yes 1/10 for the breakfast bars strange, most of your problems are easy but the two coins was a level higher

**math**

four possibilities h h h t t h t t only ONE of the four is two heads so 1/4 NOT 1/2

**physics**

take an element d A where A is the angle around the cylinder tension T to the left tension T + dT to the right then normal force toward center = (T+dT)(dA/2) + T(dA/2) = T dA for small dA so friction force = mu T dA so dT = mu T dA dT/T = mu dA ln T = mu A T = c e^mu A at A = ...

**8:01 X ?**

Now where might this question come from ?

**MATH**

Yes

**math**

I tried to tell you, you must give the whole question. do you want probability of scratched CD or unscratched CD? for example 1/4 ARE Fiction but 3/4 are NON-Fiction You did not say which you wanted.

**ah - good luck**

I have never taken business economics. I hope there is someone here who has but have not run into them.

**math**

Yes, assuming the mashed potatoes are not well known to be lumpy and the heart surgeon said French fries are ok.

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