Sunday

February 19, 2017
Total # Posts: 701

**circuits**

the zero input response of a series RLC circuit with R=80 ohms is V(c)=2e^(-2000t)cos(1000t)-4e^(-2000t)sin(1000t) V for t>0 if the initial conditions remain the same, what is the zero-input response when R=40 ohms

*March 23, 2009*

**circuits**

in a parallel RLC circuit you have L=100mH and i= inductor current i=50e^(-4000t)-10e^(-5000t) mA how do you find R and C??

*March 23, 2009*

**math**

how do you find the coordinates of the point (x, y, z) on the plane z = 1 x + 1 y + 2 which is closest to the origin

*March 16, 2009*

**math**

Find the maximum and minimum values of f(x,y)=xy on the ellipse 8x^2+y^2=4?????

*March 16, 2009*

**math**

Find three positive real numbers whose sum is 52 and whose product is a maximum?????

*March 16, 2009*

**6th grade Science**

What relationship exists between high tides and phases of the moon?

*March 16, 2009*

**Chemistry**

Write balanced equations for the formation of [Ni(NH3)6][BF4]2 starting from an anhydrous sample of nickel(II) choride hexahydrate. (3 equations necessary) I am slightly confused by this. I think the starting sample has the formula [Ni(H20)6]Cl2 Would this react with ammonia...

*March 11, 2009*

**Chemistry**

I think that nickel(II) nitrate has the formula Ni(NO3)2. As we are starting from anhyrdrous nickel nitrate I thought the first step might be to hydrate it Ni(NO3)2 + 6H2O --> [Ni(H2O)6](NO3)2 and then I thought a reaction with potassium thiocyanate KSCN but I am not sure ...

*March 11, 2009*

**Chemistry**

Write balanced equations for the formation of K4[Ni(NCS)6] starting from an anhydrous sample of nickel(II) nitrate. (3 equations necessary)

*March 11, 2009*

**Chemistry**

What is a balanced equation for the formation of [Co(NH3)5Cl]2+ from [Co(NH3)5(OH2)]3+ ?

*March 4, 2009*

**Math**

Which 3 x 3 matrix represents a reflection in the yz plane followed by inversion through the origin?

*February 24, 2009*

**trig!!**

Sin(X-y)sin(x+y)=sin^2 x - sin^2 y work on one side only...so i worked on the right =(sinx-siny)(sinx+siny) does that equal sin(x-y)sin(x+y)??? help!

*February 21, 2009*

**Trig**

Sin(X-y)sin(x+y)=sin^2 x - sin^2 y work on one side only...so i worked on the right =(sinx-siny)(sinx+siny) does that equal sin(x-y)sin(x+y)??? help!

*February 21, 2009*

**Chemistry**

What would be the molality of a solution made up of 75cm^3 of water and 0.21 g of NaCl?

*February 19, 2009*

**math**

body of mass 7 kg moves in a (counterclockwise) circular path of radius 4 meters, making one revolution every 13 seconds. You may assume the circle is in the xy-plane, and so you may ignore the third component. how do you find the centripetal force acting on the body how do ...

*February 18, 2009*

**math**

A gun has a muzzle speed of 90 meters per second. What angle of elevation should be used to hit an object 180 meters away? Neglect air resistance and use 9.8m/s^2 as the acceleration of gravity.

*February 18, 2009*

**math**

how do you find the curvature k(t) of the curve r(t)=(-2sint)i+(-2sint)j+(-4cost)k?

*February 18, 2009*

**writing**

What should I write my narrative poem about that will make my class laugh? There has to be 4 stanzas and each have to have 3 lines.

*February 16, 2009*

**Chemistry**

What is the pH of a solution made up of 50cm^3 of 1M Ethanoic Acid and 25cm^3 of 1M sodium ethanoate? Assume Ka for Ethanoic acid is 1.8 x 10^-5 mol dm^-3 I'm not quite sure how to do this. I was going to use the equation pH = pKa + log[A-]/[HA] but it doesn't seem to ...

*February 16, 2009*

**math**

Tank 1 initial contains 70 L (liters) of water and 450 g of salt, while tank 2 initially contains 20 L of water and 200 g of salt. Water containing 10 g/L of salt is poured into tank1 at a rate of 1 L/min while the mixture flowing into tank 2 contains a salt concentration of ...

*February 6, 2009*

**Spanish**

What does Pablo Neruda refer to in the last verse of his poem "La Anaconda Copper Mining Company"? "Y hay una y otra cruz torcida en las laderas infernales como única leña dispersa del árbol de la minería."

*February 6, 2009*

**8th grade**

What is domain?

*February 6, 2009*

**8th Grade Math (Algebra1)**

What is domain?

*February 3, 2009*

**Maths**

A particle rotates in a circular orbit about a point located 30cm away, with angular speed 2 rad s^-1. If the angular momentum is 0.2 Js, determine the mass of the particle. I used L=mr^2 omega and got 1.11kg A constant torque of 0.2Nm accelerates the particle for 5s. ...

*February 2, 2009*

**math**

how do you find the differential equation for t(dy/dt)+9y=8t and y(1)=6?

*January 29, 2009*

**math**

how do you find the function to satisfy y'-2y=2e^(3t) and where y(0)=-5?

*January 29, 2009*

**math**

how do you find the solution to (dy/dx)+ycos(x)=6cos(x) when the initial conditions y(0)=8? all i can get is y(x)=e^sin(x) + 7

*January 29, 2009*

**social studies**

What from nature might have given the Egyptians the belief that they would have life after death?

*January 22, 2009*

**Chemistry**

The cell Pt|H2(1 bar)|HCl(m)|AgCl(s)|Ag has an Stadard elctrode potential value of 0.2224V at 298K Using the Nernst equation, calculate a value for the EMF when the HCl concentration is 0.20M. I know what the Nernst equation is but I am unsure how to use it when I only have ...

*January 14, 2009*

**math**

How do you find the area of irregular figures using 3.14 for pi?

*January 13, 2009*

**math**

How do you find the area for an irregular figure using 3.14 for pi?

*January 13, 2009*

**english**

Say one of the funniest moments you had in school and tell them why that was so memorable and funny

*January 13, 2009*

**AP World History**

Well we are doing a project on empire building and we had to answer a couple of questions. I looked all over the internet and I can't find answers to these four questions. this is due tomorrow so I'm really desperate. Can someone help me out? My empire is the Spanish ...

*January 11, 2009*

**Chemistry**

One mole of nirtogen at 273K occupying 10 litres (state 1) is to be expanded to a volume of 20 litres at 373K (state 2). An infinite number of paths from state 1 to state 2 are possible. Consider the following important paths: (a) The gas is expanded isothermally and ...

*January 8, 2009*

**6th grade**

I'm supposed to write a paper on the "real" reason behind not running in the house. It's just why you think you shouldn't run in the house, just something funny nothing real. What should I say is the reason, that will make my class laugh?

*January 7, 2009*

**Chemistry**

A conductivity cell was calibrated using KCl solution (0.01 mol dm^-3) with a conductivity of 0.141 S m^-1 and the resistance was found to be 520 Ohms. The resistance of a saturated solution of silver chloride was found to be 3.8 x 10^5 Ohms. Calculate the solubility product ...

*January 4, 2009*

**Chemistry**

Which phosphates are found in human urine? I am writing about the discovery of phosphorus. I know that after urine was left to stand for several days and boiled to a paste it contained ammonium sodium hydrogen phosphate. Is this a constituent of fresh urine or did a reaction ...

*January 4, 2009*

**English**

Such a person as he/him is.... use "he"or"him"?

*December 20, 2008*

**Chemistry**

What is a definition for i) radial wavefunction ii) angular wavefunction What is the physical meaning of each?

*November 30, 2008*

**Chemistry**

An ammonium halide A contains 9.664% nitrogen. Identify A.

*November 20, 2008*

**math**

How else can you write x^2+4x-15?

*November 18, 2008*

**calculus**

this is part of calculus cause i need it to find critical points of a graph

*November 18, 2008*

**calculus**

solve 4x^3-6x+2=0 for all x

*November 18, 2008*

**Math**

Find the stationary points of function E(a,b) = a^4 - 2a^2 + 2b^2 and classify each of these as either a minimum, maximum or saddle point.

*November 14, 2008*

**Chemistry/Math**

No, I can't find one for a second order reaction.

*November 10, 2008*

**Chemistry/Math**

Write a differential equation describing a second order reaction – a reaction in which the rate of depletion of the concentration of the reactants depends on the square of reactants’ concentration. Solve this differential equation and hence find an expression for the...

*November 10, 2008*

**Math**

Find the specific solution for the following differential equations: a) (dy/dx)^2 - x^4 = 0 given the initial value y(1) = 0 b) dy/dx = ysinx given the initial value y(pi) = 1

*November 9, 2008*

**Maths**

P=(2J+1)exp(-(BJ(J+1))/kT) where B, k and T are constants a. Show that dP/dJ=(2-(B(2J+1)^2)/kT)exp(-BJ(J+1)/kT) b. Show that P exhibits a maximum and determine the expression for Jmax c. Find the value of P when J=0 and the limiting value of P when J becomes large(infinity).

*October 28, 2008*

**physics**

Ok, I am not sure how to about about solving this problem and have been staring at it and drawing pictures for several hours now. Do I use the spring equation for potential energy? Or is it a momentum problem where I should assume the spring has it's own velocity? Any help...

*October 19, 2008*

**Maths**

I think to plot it as a straight line you would plot logy on the y-axis against logx on the x-axis, but I'm not sure.

*October 18, 2008*

**Maths**

Transform the following relationships/funtions into linear form and identify expressions for the x and y variables. a) (x^2/a^2) + (y^2/b^2) = 1 where a and b are constants. b) k(T) = (kT/h)exp((deltaS)/R)exp(-(deltaH)/RT) where k, deltaS, deltaH and R are constants.

*October 18, 2008*

**Maths**

A(t)=A'e^(-t/r) where A(t) is the amount after time t, A' is the initial amount at t=0 and r is the decay time. Give an interpretation of the parameter r.

*October 10, 2008*

**Chemistry**

Given that for ethanoic acid pKa=4.75, calculate the pH of sodium ethanoate 0.1M.

*September 26, 2008*

**chemistry**

that's what I don't understand! :(

*September 11, 2008*

**chemistry**

a cubic piece of metal measures 5.00 cm on each edge. if the metal is nickel, whose density is 8.90g/cm cubed, what is the mass of the cube?

*September 11, 2008*

**Chemistry**

I have worked out that the element is nitrogen and the first hydride is NH3. I calculated the second hydride to have the empirical formula NH2. Would the molecular formula be N2H6? I'm not too sure about the structures.

*September 2, 2008*

**Chemistry**

Two hydrides A and B of an element X contain 17.76% and 12.58% by mass of hydrogen. Identify A and B and comment on their structures.

*September 2, 2008*

**algebra 1**

simplify 11/12-(1/3+1/4)

*July 15, 2008*

**Economics**

How to explain the differences in prices of "homogeneous" goods among sellers.

*June 25, 2008*

**English-Accented Syllables**

The accented syllable is the syllable in the word that you automatically say louder or more clearly.

*June 19, 2008*

**year 7 geography**

research which instruments are needed to measure which feature of the weather Temperature , Precipitation , Cloud cover , Cloud type , Wind direction , Wind speed , Visibility. The example i have got is visibility - eyes and instruments Does the question mean you have to put ...

*June 2, 2008*

**Calculus**

OK I understand the concept present value but I don't understand how to solve for present value in this context: Assume that you won a local contest for which you gain a continuous income stream at a rate R(t)=5000e^0.1t per year for 5 years and r=0.05. Find present value...

*April 29, 2008*

**algebra**

A certain population of bacteria doubles every 3 weeks. How long will it take for a population of 3,500 to triple?

*April 27, 2008*

**Caluculus**

Can anyone help me with this problem? Suppose that during a controlled experiment, the temperature in a beaker containing some chemical substance at time t is rising at a rate of (15/13)t^2-(7t) degrees centigrade per minute. If the temperature after 1 minute is measured to be...

*April 22, 2008*

**Spanish homework**

Sorry, I made a mistake. INstead of 'When poachers steal the eggs came' it should be 'When poachers come to steal the eggs.'

*April 12, 2008*

**Spanish homework**

Yesterday, I saw Martin Luther sitting on top of a large pumpkin. A cabbage fell from the sky and hit him in the head. Martin Luther was angry and swore at the cabbage. Most people do not know this, but Ralph Waldo Emerson is still alive. He was found buried under a layer of ...

*April 12, 2008*

**English/Spanish**

And "sorry" is triste

*April 11, 2008*

**English/Spanish**

By th wat the Spanish word for 'homework' is tarea

*April 11, 2008*

**English/Spanish**

No matter. If you need to translate it just type it in at Google Translate.

*April 11, 2008*

**SOCIAL STUDIES**

NAME A MONARCHY

*April 8, 2008*

**Social Studies**

OMG I AM SO SORRY I DIDN'T MEAN TO POST THAT ON THIIIS SITE...SORRRYY

*April 4, 2008*

**Social Studies**

WOOOOOOOOOOOOOOOOOOO ...

*April 4, 2008*

**English**

Does anyone know any specific poems or a website with poems that may relate to any of these themes...? - loss of innocence/youth - taking a chance - being yourself - imagination vs. reality any poems relating to these will do! even a poem that is opposite of the theme will be ...

*April 2, 2008*

**English**

2 questions: 1. what is the one poetic device called that's an extended metaphor and can last for mostly all of the entire poem? 2. what is the conceit that the tv shows 'rugrats' and 'family guy' share with regards to biabies and speech????? thanks!

*April 2, 2008*

**Caluculus**

Does anyone know how to find the derivative of 3x^ln(2x)?

*March 27, 2008*

**calculus**

This is stupid, but can anyone find the derivative of f(x)=8^(1-2x^2)?

*March 23, 2008*

**math**

Are these answers correct 4.0171 Answer: 4 171/10,000 Arrange in order from smallest to largest 2.05, 25/10, 2.0513, 2.059, 251/100, 20515, 2.052, 2.051. Answer: 2.05, 2.051, 2.0513, 2.0515, 2.052, 2.059, 251/100, 25/10 45.6 – 8.75 Answer: 36.85 Add thirty-eight and nine ...

*February 20, 2008*

**statistics**

In the U.S. 42% of the population has type A blood. Consider taking a sample size 4. Let y denote the number of persons in the sample with type A blood. a)Pr(y=O) b)Pr(y=1) C)Pr(y=2)

*February 5, 2008*

**Social Studies**

Did Bismarck form any tax LAWS that were not approved by the Reichstag?

*February 5, 2008*

**chemistry**

what happens when a hot empty coke can is put in a icy cold water ? what is the reaction?

*October 16, 2007*

**chemistry**

assuming that the calorimeter contains 5.00 * 100 g of water and that the initial temperature is 30.0 degree celcius. what will the final temperature be? (use the proper formula and units, and show your work below)

*October 9, 2007*

**chemistry**

the value of this quantity for water is ?

*October 9, 2007*

**chemistry**

the unit in which the quantity of heat energy is usually expressed is called the ?

*October 9, 2007*

**Legal and Ethical**

why might legal rules be insufficient for fulfilling one's ethical responsibilities?

*October 9, 2007*

**Chemistry**

I need to come up with an idea of an experiment using only baking soda, sodium chloride,a test tube, soapy water, a scale to measure the mass, and a stop watch..... any ideas...of the procedures to use..? help would be nice thank you soo much!!! =p

*September 18, 2007*

**BIOLOGY**

[Proton]+1 [neutron] 0 [electron] -1

*September 18, 2007*

**anatomy and physiology II**

why does air move into the lungs? Bob Pursley answered this question for you earlier. See you previous post of the same question

*July 13, 2007*

**anatomy and physiology II**

Any compound that can stimulate the body to produce antibodies is call what? You will find the answer at http://en.wikipedia.org/wiki/Antigen

*July 13, 2007*

**anatomy and physiology II**

air moves into the lungs bacause? Pressure difference between the lungs and the atmosphere. THe diaphram movement causes this.

*July 13, 2007*

**anatomy and physiology II**

The respiratory menbrane lining the air sacs consist of what? The actual site of gas exchange within the lungs are? the actual site of gas exchange in the lungs are at the capillaries (smallest blood vessels) You are talking about the alveoli. Since this is not my area of ...

*July 13, 2007*

**History**

I'm doing a project on Medieval nights- please help! How did chivalry reflect medieval culture especially religon? Its due on Monday and i still have HEAPS to do!!!!! Please help me! You mean Medieval knights, right? If you spell it wrong during a search on Google or any ...

*May 12, 2007*

**chemistry**

take the amount of grams (.548) and multiply it by .628 You then get .37373 (this is the concentration of ASA that the problem is focusing on) So you divide .37373 by 180.16 to figure out the amount of moles= .002075, divide this number by .250L to get your Molarity, your ...

*May 10, 2007*

**Spanish**

I would like to know if my answers to the following questions are correct: ¿Qué es lo importante para tí en un trabajo? Opino que un trabajo debe ser interesante. Me gustaría un trabajo que es un desafío y pienso que es bueno si paga bien, ...

*April 26, 2007*

**Chemistry**

I want to know the enthalpy change for this reaction which occurs in a blast furnace: Fe2O3(s) + 3C(s) --> 2Fe(l) + 3CO(g) You will need the heat of formation for CO, and ironIIIoxide, and the heatofmelting for iron. I suspect you have some temperature in mind also which ...

*April 15, 2007*

**math**

14.what value of n will result in a mean if 31 15.what value of n will result in a median of 23 15.what value of a will result in a range of 84 14,46,19,10,39,22,24,77,n Refresh your memory about the defnition of median, mode and range of a set of numbers. Then pick a value of...

*March 4, 2007*

**French**

I'm trying to figure out how you would say "he is being" in French. I know it has something to do with the present participle "étant," but we haven't really gotten very far into this yet in class. Would you say "il est étant"...

*March 4, 2007*

**home economics**

what are the different names of equipment used for cooking? Please post the names of the equipment that you know. Then, we'll be glad to help you find more names, if necessary.

*February 5, 2007*

**GEOMETTRY**

HOW MANY VERTEXS DOES A HEXAGON HAVE? Draw a hexagon, a six sided figure, and count the vertices. Thank you for using the Jiskha Homework Help Forum. The following site may help you to see this: http://en.wikipedia.org/wiki/Hexagonal_tiling seee

*January 7, 2007*

**firms**

what are 3 disadvantages of firms merging? Sometimes when firms merge, the company is simply too large or diverse for the management to handle. Sometimes the profits from one of the businesses don't increase as fast as was originally expected. Also -- there's a ...

*November 13, 2006*

**pre-calculus**

THe sume of 2 positive numbers is 20. Find the two numbers such that 1) the sum of the square is minimum b) the product of one and the square is maximum. c) the product of the square and one and the cube of the other is maximum I will be happy to critique your work on this.

*November 11, 2006*