Wednesday

November 26, 2014

November 26, 2014

Total # Posts: 1,777

**trig**

write sin4xcos2 as the sum or difference of two functions. answers: 1/2(cos6x+cos2x), 1/2(cos2x-cos6x), 1/2(sin6x+sin2x), sin6x-sin2x
*May 17, 2012*

**trig**

find the angle between vector U=<2,3> and V=<1,-5> answers: 88 degrees, 45 degrees, 135 degrees, or 92 degrees...?
*May 17, 2012*

**Chemistry**

A solution of formic acid 0.20 M has a pH of 5.0. What is its Ka value? a) 5.0 x 10-10 b) 1.0 x 10-5 c) 5.0 x 10-5 d) 25
*May 16, 2012*

**Chemistry**

Mols benzoic acid = 12.2g/122.12g = 0.0999 Int. Concentration of Benzoic acid = 0.0999 mol/ 0.500L = 0.1998 M Ka = 6.3 x 10-5 = (x)(x)/0.1998 – x X = [H+] = * M pH = -log(*) = * Sorry, this question is just really confusing me..
*May 16, 2012*

**Chemistry**

Thanks so much, you're an awesome help.
*May 16, 2012*

**Chemistry**

Mols benzoic acid = 12.2g/122.12g = 0.0999 Int. Concentration of Benzoic acid = 0.0999 mol/ 0.500L = 0.1998 M Ka = 6.3 x 10-5 = (x)(x)/0.1998 – x X = [H+] = * M pH = -log(*) = * Sorry, this question is just really confusing me..
*May 16, 2012*

**Chemistry**

Calculate the pH of a solution prepared by dissolving 12.2 g of benzoic acid in enough water to produce a 500 mL solution. Ka = 6.3 x 10^-5
*May 16, 2012*

**Chemistry**

Can a solution of CrCl3 be stored in an aluminum container?
*May 15, 2012*

**Chemistry**

Using the following spontaneous reactions, classify the 3 metals involved (Cr, Sn, Al) according to increasing reductant properties. a) 2Cr + 3Sn2+ 2Cr3+ + 3Sn b) Al + Cr3+ Al3+ + Cr
*May 15, 2012*

**Chemistry**

Which pair of ions will be most likely to react at standard state conditions? 1. a) MnO4- and Sn2+ 2. b) Zn2+ and Cl- 3. c) I- and Cu 4. d) Fe3+ and Cu2+
*May 15, 2012*

**Chemistry**

If a piece of copper metal is dipped into a solution containing Cr3+ ions, what will happen? Explain with Ev values
*May 15, 2012*

**Chemistry**

Pb(NO3)2(aq) 2 x 10-3 M Na2SO4(aq) 2 x 10-3 M Pb(NO3)2(aq) + NaSO4(aq) → PbSO4(s)+ 2NaNO3(aq) a) What are the concentrations of each ion within this solution? b) If 1L of each solution is mixed; will a precipitate form? why?
*May 15, 2012*

**Spanish-8th grade Help!**

Thank you- I think what I put is right- I've rechecked it but it seems so odd the way I have it.I know it's a reflexive so maybe it is correct.
*May 12, 2012*

**Soanish-8th grade Help!**

I'm trying to conjugate this in the past tense tú/presentarse would I conjugate it in past tense like this- (tú te presentaste) Something looks wrong with it
*May 12, 2012*

**math**

what is the first step in solving the equation x/5 - 9=6?
*May 9, 2012*

**Physics Help**

So is there no shift? and if so why is that the case?
*May 9, 2012*

**Physics Help**

If we witness events taking place on the moon, where gravitation is weaker than on Earth, would we expect to see a gravitational red shift or a gravitational blue shift? and Explain please a)blue shift b)red shift c)no shift
*May 9, 2012*

**Chemistry**

The following reaction has a Delta G value of 42.6 kJ/mol at 25oC: HB(aq) +H2O(l) --> H3O+(aq) +B-(aq) Calculate Ka for the acid HB.
*May 7, 2012*

**Physics Help!!**

Comparing Einstein's and Newton's theories of gravitation, can the correspondence principle be applied? and Why or Why not? a)Yes b)No
*May 7, 2012*

**Physics Help please**

If we witness events taking place on the moon, where gravitation is weaker than on Earth, would we expect to see a gravitational red shift or a gravitational blue shift? and Explain please a)blue shift b)red shift c)no shift
*May 7, 2012*

**Chemisttry**

A 100.0-mL sample of 0.250 M aniline (C6H5NH2) is titrated with 0.500 M HCl. What is the pH at the equivalence point?
*May 6, 2012*

**Chemistry**

You take 326 g of a solid (melting point = 57.6oC, enthalpy of fusion = 346 J/g) and let it melt in 757 g of water, and the water temperature decreases from its initial temperature to 57.6oC. Calculate the initial temperature of the water. (Note that the speciﬁc heat ...
*May 6, 2012*

**Physics Help!!**

A passenger on an interplanetary express bus traveling at v = 0.94c takes a seven-minute catnap by his watch. How long does the nap last from your vantage point on a fixed planet?
*May 5, 2012*

**Physics Help please**

A bus moving with speed 0.93c is 65 feet long according to its passengers and driver. What is its length from your vantage point on a fixed planet?
*May 5, 2012*

**Chemistry**

Thanks it worked perfectly
*May 3, 2012*

**Chemistry**

there isnt a kp or a kc
*May 3, 2012*

**Chemistry**

Nitrogen gas (N2) reacts with hydrogen gas (H2) to form ammonia (NH3). At 200 oC in a closed container, 1.1 atm of nitrogen gas is mixed with 2.1 atm of hydrogen gas in an otherwise empty container. At equilibrium, the total pressure is 2.2 atm. Calculate the partial pressure ...
*May 3, 2012*

**Physics!!**

Green light is emitted when electrons in a substance make a particular energy-level transition. If blue light were instead emitted from the same substance, would it correspond to a greater or lesser change of energy in the atom? and why?
*May 2, 2012*

**calculus**

what is the integer values of n that satisfies this inequality -5<3n<12? Please answer :)
*May 1, 2012*

**chemistry**

Gaseous butane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 16.9 g of butane is mixed with 39. g of oxygen. Calculate the minimum mass of butane that could be left over by the chemical reaction. Round your answer to 2 significant...
*April 30, 2012*

**chemistry**

Gaseous butane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 16.9 g of butane is mixed with 39. g of oxygen. Calculate the minimum mass of butane that could be left over by the chemical reaction. Round your answer to 2 significant...
*April 30, 2012*

**math**

if you invest 500 dollars in a savings account that pays 8% interest per year, compounded quarterly, how much will you have in the account at the end of 11.6 years?
*April 26, 2012*

**statistics**

What type of statistical information would I include in my report to determine our year-to-date performance of our division; example, mean, median, or standard deviation.
*April 26, 2012*

**Life orientation**

It damages communities
*April 24, 2012*

**Math**

In an election, ethan got 5 fewer votes than christohper,who got 3 more votes than olivia, who got 4 fewer votes than Ava. How many more votes did ava get than ethan ?
*April 21, 2012*

**math**

Given P(x) = x^3 - 3x^2 - 5x + 10 a evaluate P9x) for each integer value of x from -3 through 5 b. Prove that 5 is an upper bound on the zeros of P(x)
*April 21, 2012*

**Physics**

Two masses, m1=3kg and m2=2kg, are suspended with a massless rope over a pulley of mass M = 10kg. The pulley turns without friction and may be modeled as a uniform disk of radius R=.1m. You may neglect the size of the masses. The rope does not slip on the pulley. The system ...
*April 18, 2012*

**Calculus**

Suppose vectors a and b are vectors such that a x b =(3,1,4). What is the cross product of twice of a with twice of b?
*April 17, 2012*

**Calculus/Physics Please help!!**

An intravenous line provides a continuous flow of drug directly into the blood. Assuming no initial drug in the blood, the amount of drug in the blood t hours after the dosing begins in m(t) - (a/k)(1-e^-kt), for t (=>)0, where k is the rate constant (again related to half ...
*April 17, 2012*

**CALCULUS PLEASE HELP!!**

suppose m(0) milligrams of a drug are put in the blood of an injection. The amount of drug t hours after the injection is given by m(t)=m(o)e^-kt, for t (=>) 0, where k is the rate constant, which is related to the half life. we also treat oral administration of drugs as an...
*April 17, 2012*

**Calculus**

Could someone please explain on how to do this question step-by-step. Thank you! A bolt is being loosened by a 40 cm wrench. The torque in this situation has a magnitude of 12 J and the force makes an angle of 60 degree with the wrench. What is the magnitude of the force used ...
*April 17, 2012*

**CALCULUS PLEASE HELP!!**

suppose m(0) milligrams of a drug are put in the blood of an injection. The amount of drug t hours after the injection is given by m(t)=m(o)e^-kt, for t (=>) 0, where k is the rate constant, which is related to the half life. we also treat oral administration of drugs as an...
*April 15, 2012*

**Calculas**

suppose m(0) milligrams of a drug are put in the blood of an injection. The amount of drug t hours after the injection is given by m(t)=m(o)e^-kt, for t (=>) 0, where k is the rate constant, which is related to the half life. we also treat oral administration of drugs as an...
*April 15, 2012*

**Calculus**

I checked in the book answer and the site u gave me matched with the answer. How did the website get solutions as: x= -3.28183 x= -1.863
*April 14, 2012*

**Calculus**

Use the algorithm for curve sketching to sketch the graph of each function. a) f(x) 4x^3+6x^2-24x-2 1. First to find intercepts y=0 0=4x^3+6x^2-24x-2 =2(2x^3+3x^3-12x-1) I don't know how to find the x-intercept. I can't use quadratic formula or synthetic division :S
*April 14, 2012*

**Math help**

So do I draw lines through the vertices?
*April 12, 2012*

**Math help**

Sketch the graph: (x+2)^2/25-(y+4)^2/25=1 I don't understand this at all! When I tried graphing it I just had two lines going through the center, which is (-2,-4). But it should be a hyperbola, right? Could anyone help me?
*April 12, 2012*

**World History**

During the Columbian Exchange what diseases were brought from the new world to Europe?
*April 11, 2012*

**HELP PLEASE PHYSICS!!**

Thank you!!!
*April 9, 2012*

**HELP PLEASE PHYSICS!! **

How much does it cost to operate a 100 W lamp continuously for 1 week if the power utility rate is 8/kWh? answer in $
*April 9, 2012*

**Physics Need Help PLEASE**

okay great!!! Thank you again!!!! you do a wonderful job!!!!
*April 9, 2012*

**Physics Need Help PLEASE**

its looking for the N/C I got 4*10^-21 but I'm not getting it correct
*April 9, 2012*

**Physics Need Help PLEASE**

Thank you so much Elena that helped me out a lot! I was wondering if you could also help me with another question. A droplet of ink in an industrial ink-jet printer carries a charge of 6 10-13 C and is deflected onto paper by a force of 2.4 10-7 N. Find the strength of the ...
*April 9, 2012*

**Physics Need Help PLEASE**

Two point charges are separated by 8 cm. The attractive force between them is 14 N. If the two charges attracting each other have equal magnitude, what is the magnitude of each charge?
*April 9, 2012*

**Calculus**

Which plane goes through the origin and is perpendicular to the line r=(2,-2,1) + s(2,3,-4), seR? a) 2x-2y+z=0 b) 2x+3y-4z=0 c) 2x+3y+z-4=0 d) none of the above. I got D, none of the above. I have substituted and couldn't find the answer equal to zero.
*April 8, 2012*

**Calculus**

Are the points P(1,2), Q(7,3) and R(-2,1) o the line with vector equation r=(19,5) +s(6,1), SeR
*April 8, 2012*

**Calculus**

which pair of lines are perpendicular? a) 2x + 3y - 7=0, -3x - 2y + 2=0 b) 2x - 3y + 2=0, 5x - 7y + 2=0 c) -4x + y - 3=0, x + 4y=0 d) -5x + y + 1=0, 5x + y + 1=0 Please explain. I know we have to use the dot product :3
*April 7, 2012*

**engineering mechanics**

14 degrees
*April 5, 2012*

**Calculus**

A rusted bolt requires 30 J of torque to be loosened. If only 40 N of force is applied to a wrench with which it makes a 90° angle, how long is wrench?
*April 2, 2012*

**Calculus**

Determine the value(s) of k such that the area of the parallelogram formed by vectors a = (k+1, 1,-2) and b =(k,3,0) is [sqrt(41)]
*April 2, 2012*

**Calculus**

For which value(s) of k will the dot product of the vectors (k,2k-1, 3) and (k,5,-4) be 7? I did this so far, 2k-1=5 6/2 k=3
*March 29, 2012*

**College Chemistry**

Write three equations (including ΔH values) that represent the heats of formation for each C6H12O6(s), CO2(g), and H2O(l). (Hint: look up heats of formation for each participant)
*March 29, 2012*

**Calculus**

Two force vectors act on an object and the dot product of the two vectors is 20. If both of the force vectors are doubled in magnitude, what is their new dot product?
*March 29, 2012*

**Calculus**

Sorry for the confusion. May I ask why my answer does not work? :S its asking for the vertices, not equal to Point P.
*March 27, 2012*

**Calculus**

Why add?
*March 27, 2012*

**Calculus**

I am bit of confused from this question. I have shown the work below and to subtract, am I supposed to be X2 - X1, Y2-Y1, Z2-Z1? or X1-X2, Y1-Y2, Z1-Z2? ------------------------------------ A triangle has sides formed by the vectors PA=(2,7,3) and PB=(6,2,2). The point P=(1,3,...
*March 27, 2012*

**Physics**

A box of mass m=1.5 kg is attached to a spring with force constant k=12 and suspended on a frictionless incline that makes a 30 degree angle with respect to the horizontal. With the spring in its unstretched length, the box is released from rest at x=0. The box slides down the...
*March 27, 2012*

**Calculus**

I am bit of confused from this question. I have shown the work below and to subtract, am I supposed to be X2 - X1, Y2-Y1, Z2-Z1? or X1-X2, Y1-Y2, Z1-Z2? ------------------------------------ A triangle has sides formed by the vectors PA=(2,7,3) and PB=(6,2,2). The point P=(1,3,...
*March 27, 2012*

**Calculus**

1. Which of the following sets of vectors spans [r^2] ? a) {(1,1), (-2,-2)} b) {(1,1), (1,2)} c) {(1,2), (1/2,2)} d) {(-1,1), (1,-1)} 2. Which of the following sets of vectors spans [r^3] ? a) {(1,1,1), (2,2,2)} b) {(1,3,1), (2,2,2)} c) {(1,2,1), (1/2,1,1/2)} d) {(1,3,2), (-1...
*March 27, 2012*

**Calculus**

Point A=(1,3,4) and point B=(-2,2,0). Determine AB. a) (3,1,4) b) (-3,-1,-4) c) (-1,5,4) d) (1,5,4) I chose answer C. 2. A goes from (2,1) to (4,-1) Determine the components of A. a) (6,0) b) (-2,2) c) (2,-2) d) (0,6)
*March 26, 2012*

**Calculus**

Vector D represents: URL is here imgur dot com/AX4EN a) A+B b) A-B c) C+B d) A+C I chose answer A. Is that the correct answer?
*March 26, 2012*

**Chemistry**

How many moles of nitrogen are needed to produce 1.52 moles of nitrogen (ll) oxide ? N2 + O2 > FeCL3 + 3H20
*March 24, 2012*

**Algebra**

Use the substitution method to solve -x + 3y=24 5x +8y=-5
*March 23, 2012*

**Calculus and vectors**

|C|=5 and |D|=8. The angle formed by vectors C and D is 35 degrees, and the angle formed by vectors A and C is 40 degrees. Determine |B|. Could someone explain this question
*March 23, 2012*

**fractions**

6/8 pizza left, which can be reduced to 3/4.
*March 23, 2012*

**Calculus and vectors-Help~David**

Thank you very much!
*March 22, 2012*

**Calculus and vectors-Help~David**

Rectangular prism is defined by vectors (2,0,0)(0,9,5) and (0,0,3). Find the volume. I have done this so far, would anyone please verify this. (2,0,0)(0,9,6) (0-2, 9-0, 6-0) =(-2,9,6) (-2,9,6)(0,0,3) =(2,-9,-3) (2)(-9)(-3)=54 cm^3 Therefore volume is 54 cm^3
*March 22, 2012*

**Calculus**

Is B=(2,-1,-6)?
*March 22, 2012*

**Calculus **

If A=(1,2,4) and Vector A+B =(3,1,-2). What is B?
*March 22, 2012*

**Calculus and vectors @ Bob Purs**

I multipled by 2 since its a rectangle, there is an example of similiar to this question but its a triangle.
*March 22, 2012*

**Calculus and vectors @ Bob Purs**

Rectangle side is represented by (2,3) and (-6,4). Find the perimeter of rectangle. Is this correct? (-6-2), 4-3) sqrt(8^2+1^2) sqrt(65) =8.062257748(2) =16.124?
*March 22, 2012*

**Math**

Is this correct? ((-6-2), 4-3) sqrt(8^2+1^2) sqrt(65) =8.062257748(2) =16.124?
*March 22, 2012*

**Math**

Rectangle side is represented by (2,3) and (-6,4). Find the perimeter of rectangle. Do I have to find the magnitude of (2,3) and (-6,4) and square root the answer?
*March 22, 2012*

**Calculus**

Thank you for answering. Don't I have to find the magnitude then use square root of the answer and multiply by 2? If so, could you show it.
*March 22, 2012*

**Calculus **

Rectangle side is represented by (2,3) and (-6,4). Find the perimeter of rectangle. Could someone please help~
*March 22, 2012*

**Calculus and vectors**

Could someone explain to me how I can find the area/perimeter/volume of a rectangular prism if I am given R^3 points. For example find area of rectangular prism given pts (2,3,4)(5,3,2), similar to this.
*March 21, 2012*

**Calculus and vectors**

Bob can swim at a rate of 5km/h. He is in a river that is flowing at a rate of 9 km/h. a) if bob swims upstream, what is his relative velocity to the ground? b)if bob swims downstream, what is his relative velocity to the ground? c) Someone decides to help Bob out of the water...
*March 20, 2012*

**physics**

Bob can swim at a rate of 5km/h. He is in a river that is flowing at a rate of 9 km/h. a) if bob swims upstream, what is his relative velocity to the ground? b)if bob swims downstream, what is his relative velocity to the ground? c) Someone decides to help Bob out of the water...
*March 19, 2012*

**Math**

Bob can swim at a rate of 5km/h. He is in a river that is flowing at a rate of 9 km/h. a) if bob swims upstream, what is his relative velocity to the ground? b)if bob swims downstream, what is his relative velocity to the ground? c) Someone decides to help Bob out of the water...
*March 19, 2012*

**Chemistry**

Why doesn't water undergo electrolysis? Why does Na2SO4 undergo electrolysis?
*March 19, 2012*

**trig**

verify that 2/1+cos theta - tan squared (theta/2) = 1
*March 19, 2012*

**Math**

Multiplying a vector by a scalar results in: a) a scalar b) a perpendicular vector c) a collinear vector c) a parallel scalar
*March 18, 2012*

**Math**

Sabrina and John cut a pie into 4 slices. Sabrina eats 2 slices. John eats the rest. What fraction names the part of the pie that John eats?
*March 14, 2012*

**Biology**

Among humans, increased interest in food intake normally occurs _____. only after the production of glucose in the liver can no longer meet metabolic needs when fewer calories are taken in than are expended, but only after the body depletes its reserves of fat in the liver via...
*March 14, 2012*

**SCIENCE/ earth**

Thanks Ms Sue!!!
*March 14, 2012*

**SCIENCE/ earth**

plate tectonics crossword puzzle what Qs and As can i use??????? PLZZZZZ HELP ME!!!!!!!!!!!!!
*March 14, 2012*

**PHYSICS**

A space explorer is 4.6 billion km away from a certain star, and observes that the gravitational force of attraction exerted on the spacecraft by the star is 500 N. What will the force become when the craft has approached to a position 2 billion km from the star?
*March 11, 2012*

**PHYSICS**

Determine the value for the acceleration due to gravity at the surface of the planet Mars, given the following data: Mass of Mars = 6 .42 x 10^23 kg Radius of Mars = 3.37 x 10^6 m Thanks!
*March 10, 2012*

**chemistri**

so are dispersion forces one of them?
*March 10, 2012*

**chemistri**

what are van der waals forces
*March 10, 2012*

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