# Posts by andy

Total # Posts: 940

**chemistry**

Thanks Dr Bob, I am horrible at algebra.... But since reading your reasoning I have now got ammunition to be able to reason out the answer....I will try harder and study more.. Thanks for all your advice it was great Andy

*May 9, 2010*

**chemistry**

Dr BOB, How this (3+0.844)^2/(3-0.844)^2=3.18(rounded) sqrt(3.18)=1.7832 So there fore answer=0.844 which is one of the answers! Am I on the right track? Andy

*May 9, 2010*

**chemistry**

DR Bob, If I plug in 0.01 for x then the answer is (3.000+0.01)times(3.000+0.01)divided by (3.000-0.01)times(3.000-0.01)answer according to my calculator says 9.0601.....ok how does that relate to the answer??am I to keep guessing what X isuntill I get the answer? or is there ...

*May 9, 2010*

**chemistry**

DR bob I got that far no probs...But don't know how to do the last bit could you expand please Thanks andy

*May 9, 2010*

**chemistry**

For the equilibrium H2(g)+CO2(g)<-->H2O(g)+CO(g) Kc=3.18 at 1106 K.If each of the four species was initially present at a concentration of 3.000M,Calculate the equilibrium concentration of the CO (g) at this temperature. Choices 0.844 3.268 3.844 3.460 2.156 Thanks ...

*May 9, 2010*

**Chemisty 11 U**

Determin the number of oxygen atmos in 1.75kg of potassium sulfate.

*April 27, 2010*

**Chemisty 11 U**

where??

*April 27, 2010*

**Chemisty 11 U**

Determin the number of oxygen atmos in 1.75kg of potassium sulfate.

*April 27, 2010*

**Chemisty 11 U**

Determin the number of oxygen atmos in 1.75kg of potassium sulfate.

*April 27, 2010*

**Chemisty 11**

thank you

*April 26, 2010*

**Chemisty 11**

Why is it important to use the correct salt-sand mix on highways during storms? Help please this is for my Chemisty Project

*April 26, 2010*

**physics helpppp**

Figure 10-35a shows a disk that can rotate about an axis at a radial distance h from the center of the disk. Figure 10-35b gives the rotational inertia I of the disk about the axis as a function of that distance h, from the center out to the edge of the disk. The scale on the ...

*April 18, 2010*

**physics please help**

Find Beta and Gamma for an electron that has a kinetic energy of 6.00 keV. gamma = KE/MoC^2 + 1 Beta = 1/gamma^2 + 1 gamma = 1.011723381 Beta = 1.9769592 I am getting gamma right but I am getting Beta wrong what I'm I doing wrong??

*April 18, 2010*

**physics**

Find Beta and Gamma for an electron that has a kinetic energy of 6.00 keV. â? gamma = KE/MoC^2 + 1 Beta = 1/gamma^2 + 1 gamma = 1.011723381 Beta = 1.9769592 I got gamma correct but my answer but im getting gamma incorrect can anyone explain what could be wrong

*April 17, 2010*

**physics**

Spaceship I, which contains students taking a physics exam, approaches Earth with a speed of 0.640 c, while spaceship II, which contains instructors proctoring the exam, moves away from Earth at 0.280 c, as in Figure P26.27. If the instructors in spaceship II stop the exam ...

*April 16, 2010*

**physics**

Spaceship I, which contains students taking a physics exam, approaches Earth with a speed of 0.640 c, while spaceship II, which contains instructors proctoring the exam, moves away from Earth at 0.280 c, as in Figure P26.27. If the instructors in spaceship II stop the exam ...

*April 16, 2010*

**physics**

Can a person, in principle, travel from Earth to the galactic center (which is about 2.3e4 lightyears distant) in a normal lifetime? Explain, using either time-dilation or length contraction arguments. If they want to make the trip in 24 y what distance would the person ...

*April 15, 2010*

**physics**

drwls you are awesome!!

*April 15, 2010*

**physics**

The average lifetime of muons at rest is 2.20 us. A laboratory measurement on muons traveling in a beam emerging from a particle accelerator yields an average muon lifetime of 19.668 us. What is the speed of the muons in the laboratory? u=((1-(2.2e-6/19.688e-6)^2))^(1/2)=0....

*April 15, 2010*

**chemistry**

When CO(g) (38.11 grams) and 96.48 grams of Cl2(g) in a 140.0 L reaction vessel at 782.0 K are allowed to come to equilibrium the mixture contains 0.4080 mol of Cl2CO(g). What is the equilibrium concentration (mol/L) of CO(g)? CO(g)+Cl2(g) = Cl2CO(g) Can anyone help with the ...

*April 14, 2010*

**chemistry**

When CS2(g) (545.0 grams) and 57.71 grams of H2(g) in a 200.0 L reaction vessel at 961.0 K are allowed to come to equilibrium the mixture contains 2.447 mol of CH4(g). What concentration (mol/L) of CS2(g) reacted? Molar Mass CS2(g) 76.15 H2(g) 2.016 CH4(g) 16.043 H2S(g) 34.086...

*April 14, 2010*

**physics**

is rest mass energy 9.11e-31 * (3e8)^2 ?? and do I need to convert from J to ev to KeV? Thanks for the help

*April 14, 2010*

**physics**

How much work must be done to increase the speed of an electron from 0.200c to 0.210c? In (MeV)

*April 14, 2010*

**physics**

A.An observer moving at a speed of 0.810 c relative to a rod measures its length to be 2.00 m and sees its length to be oriented at 30.0 degrees with respect to the direction of motion. What is the proper length of the rod? B.What is the orientation angle in a reference frame ...

*April 14, 2010*

**chemistry**

The value of the equilibrium constant (Kc) as represented by the first chemical equation is 2.70 x 10-3 at 1200 K. Calculate the value of the equilibrium constant (Kc) for the second equation at the same temperature. Express answer in scientific notation. F2(g) = 2F(g) 2F(g...

*April 13, 2010*

**chemistry**

How do you figure out the answer for the reverse reaction? At 350 K the value of Kp for the equilibrium represented by the balanced equation is 2.87 x 10-2. Calculate the value of Kc for the reverse reaction at the same temperature. Express answer in scientific notation. 2NOBr...

*April 13, 2010*

**biology**

1. Some photosynthetic bacteria are able to harvest 900-nanometer light (4 points). A. What is the energy in kilocalories of a mole (an einstein) of 900-nanometer light? B. What is the minimum number of 900 nanometer photons needed to form one molecule of ATP from ADP and ...

*April 13, 2010*

**chemistry**

Calculate the value of the equilibrium constant (Kp) for the reaction shown, if F(g) was found to be 96.80 % decomposed at 1000 K when its initial pressure was 4.638 atm. The initial pressure of the reaction products is 0 atm. 2F(g) = F2(g)

*April 8, 2010*

**chemistry**

On this problem I keep getting the wrong answer. I am subtracting the initial concentration of Cl2 by the equilibrium concentration then using the difference to subtract for the rest using the mole ratios. Then i used the keq constant equation of concentration of products over...

*April 8, 2010*

**chemistry**

I keep getting the wrong answer for this one can someone help. The initial concentration for the compounds involved in the reaction displayed were determined to be [NOCl(g)] = 0.1738 mol/L, [NO(g)] = 0.1991 mol/L, [Cl2(g)] = 0.000005938 mol/L. Calculate the value of the ...

*April 8, 2010*

**chemistry**

I was having trouble with this problem. initial pressure for the compounds involved in the reaction displayed were determined to be P(CO(g)) = 0.5794 atm, P(H2O(g)) = 0.5662 atm, P(CO2(g)) = 0.7950 atm, P(H2(g)) = 0.2754 atm. Calculate the value of the equilibrium constant (...

*April 8, 2010*

**chemistry**

I also had a problem with this type of questionthe initial pressure of NOCl(g) is 4.329 atm, calculate the % of NOCl(g) left over after the reaction reaches equilibrium according to the balanced equation. The value of Kp at 400.0 °C is 1.99. The initial pressure of the ...

*April 8, 2010*

**chemistry**

i forgot to enter the formula: CO(g)+H2O(g) = CO2(g)+H2(g)

*April 8, 2010*

**chemistry**

I was having trouble with this problem. initial pressure for the compounds involved in the reaction displayed were determined to be P(CO(g)) = 0.5794 atm, P(H2O(g)) = 0.5662 atm, P(CO2(g)) = 0.7950 atm, P(H2(g)) = 0.2754 atm. Calculate the value of the equilibrium constant (Kp...

*April 8, 2010*

**Computer Science**

w w w (dot)cs(dot)umass(dot)edu(slash)~verts(slash)coins105(slash)quizzes(slash)images(slash)hw10(dot)gif Using the constants in cells A2:A9, create formulae for cells A12:A15 (surrounded by a dark line) to compute the corresponding "derived" physical constants ...

*April 4, 2010*

**chemistry**

How many millimoles of H+ are present in 1.00 L of 1.24 M CF3CO2H solution?

*April 1, 2010*

**Chemistry**

can someone explain how to find 1.Chemical shift (ppm) 2.Multiplicity (splitting) 3.intergration (# of h's) for C2H6O

*March 29, 2010*

**Chemistry NMR**

the spectrum didn't turn out but peak one 2 hydrogen approx 4.10 ppm peak two 1 hydrogen approx 2.00 ppm peak three 3 hydrogen approx 1.10 ppm

*March 29, 2010*

**Chemistry NMR**

3h 2h 1h 4 3 2 1 0 ppm C2H6O I tried to duplicate the spectrum for this compound. I'm guessing its ethanol but I don't know how to answer the following questions for each peak 1,2,3....1.Chemical shift(ppm) 2.Multiplicity(splitting) 3.Integration(# of h's)

*March 29, 2010*

**Behavior Science**

it not only affects the human mind, but the body as well

*March 28, 2010*

**physics**

there is a figure that accompanies this problem the mirror is perpendicular to the screen where the mirror is the x-axis and the screen is the y-axis does that help because I am having trouble with this one

*March 24, 2010*

**physics**

Interference effects are produced at point P on a screen as a result of direct rays from a 518 nm source and reflected rays off the mirror.If the source is 99 m to the left of the screen, and 1.15 cm above the mirror, calculate the distance y (in millimeters) to the first dark...

*March 24, 2010*

**physics**

Interference effects are produced at point P on a screen as a result of direct rays from a 518 nm source and reflected rays off the mirror.If the source is 99 m to the left of the screen, and 1.15 cm above the mirror, calculate the distance y (in millimeters) to the first dark...

*March 24, 2010*

**physics**

A.A pair of narrow, parallel slits separated by a distance of 0.335 mm are illuminated by green laser light with wavelength = 543.0 nm. The interference pattern is observed on a screen 2.43 m from the plane of the parallel slits. Calculate the distance from the central maximum...

*March 21, 2010*

**physics**

Imagine an airplane passenger looking down on two automobiles side by side on the ground. According to the Rayleigh criterion, at what maximum altitude will the passenger just resolve them as two if their center-to-center separation is 3.3 m? Assume that the passenger has good...

*March 19, 2010*

**College Math**

they will have the same slope y=mx+b y=2x+2 and y=2x+4 are parallel

*March 18, 2010*

**physics**

Imagine an airplane passenger looking down on two automobiles side by side on the ground. According to the Rayleigh criterion, at what maximum altitude will the passenger just resolve them as two if their center-to-center separation is 3.3 m? Assume that the passenger has good...

*March 18, 2010*

**math**

45/60 = 3/4 numerator/denominator 192=numerator*denominator then its easy enough to just plug in numbers...so find fractions that are equal to 3/4...such as 9/12 12/16 15/20

*March 18, 2010*

**physics**

single-slit diffraction pattern is formed when light of 680.0 nm is passed through a narrow slit. The pattern is viewed on a screen placed one meter from the slit. What is the width of the slit (mm) if the width of the central maximum is 2.69 cm?

*March 16, 2010*

**physics**

A 17.1 cm focal-length lens is used to project 35 mm slides onto a screen 4.77 m from the projector lens. What must be the width of the screen ( m) if the image of the slide is to just fill the screen? The width of the image on the slide is 34.3 mm.

*March 14, 2010*

**French**

I've been working hard on this french composition and I'm afraid I can no longer pick out the mistakes and accurately proofread it. The following composition is on Toulouse Lautrec and Montmartre: Un des plus célèbres post impressionnistes faisait ...

*March 7, 2010*

**math**

a few months ago, Van had 100 days to wait until his birthday. His wait is 98% over. Today is Monday. What day is Van's birthday?

*March 2, 2010*

**Corporate Finance**

1. The Federal Reserve recently shifted its monetary policy, causing Lasik Vision's WACC to change. Lasik had recently analyzed the project whose cash flows are shown below. However, the CFO wants to reconsider this and all other proposed projects in view of the Fed action...

*March 1, 2010*

**Corporate Finance**

1. Langston Labs has an overall (composite) WACC of 10%, which reflects the cost of capital for its average asset. Its assets vary widely in risk, and Langston evaluates low-risk projects with a WACC of 8%, average projects at 10%, and high-risk projects at 12%. The company is...

*March 1, 2010*

**Corporate Finance**

19. Fool Proof Software is considering a new project whose data are shown below. The equipment that would be used has a 3-year tax life, and the MACRS rates for such property are 33%, 45%, 15%, and 7% for Years 1 through 4. Revenues and other operating costs are expected to be...

*March 1, 2010*

**Corporate Finance**

1. TexMex Products is considering a new salsa whose data are shown below. The equipment that would be used would be depreciated by the straight-line method over its 3-year life, would have zero salvage value, and no new working capital would be required. Revenues and other ...

*March 1, 2010*

**physics**

haha thanks bobpursley you are right that's the problem

*February 21, 2010*

**physics**

This is a two part question the first part was to find the number of turns which is 535 like you said. L=(mewsub0*N^2*A)/length A= .5 pi r^2 N=number of turns=535 mewsubO= 4 pi 10^-7 thats the formula to use but I'm not getting a correct answer any suggestions?

*February 21, 2010*

**physics**

A solenoid is wound with a single layer of insulated copper wire of diameter 2.800 mm and has a diameter 5.000 cm and is 1.500 m long. Assume that the adjacent wires touch and that the insulation thickness is negligible. what is the inductance per meter(H/m) for the solenoid ...

*February 21, 2010*

**physics**

A solenoid is wound with a single layer of insulated copper wire of diameter 2.800 mm and has a diameter 5.000 cm and is 1.500 m long. Assume that the adjacent wires touch and that the insulation thickness negligible. what is the inductance per meter(H/m) for the solenoid near...

*February 21, 2010*

**Chemistry**

Calculate the volume ( L ) of the solute water and the volume ( L ) of the solvent tetrahydrofuran that should be added to generate 4.73 kg of a solution that is 1.36 m water.

*February 13, 2010*

**Chemistry**

If 49.6 mL of liquid CS2 and 12.8 g of gaseous Cl2 are reacted stoichiometrically according to the balanced equation, how many moles of liquid S2Cl2 are produced? CS2(l) + 3Cl2(g) ¨ CCl4(l) + S2Cl2(l)

*February 12, 2010*

**Chem**

What volume ( L ) of the solute ethanol should be mixed with 0.546 L of the solvent C4H8O to make a solution that is 8.44 m ethanol.

*February 12, 2010*

**Chemistry**

Mole of NaBr=(.893M)(.750L)= .6679 mole mole of Cl2= (1.00atm)(22.4L)=n(.0821)(273.15k) n= .998858 mole How do u determine the limiting reagent?

*February 12, 2010*

**Chemistry**

If 750 mL of 0.893 M aqueous NaBr and 11.6 L of gaseous Cl2 measured at STP are reacted stoichiometrically according to the balanced equation, how many milliliters of 3.93 M aqueous NaCl are produced? 2NaBr(aq) + Cl2(g) ¨ 2NaCl(aq) + Br2(l)

*February 12, 2010*

**Chemistry**

Can anyone please tell me what can you say about the purity of the compound extracted based on your TLC results? Thanks

*February 9, 2010*

**chemistry**

Based on the balanced equation C4H8S + 7O2 = 4CO2 + 4H2O + SO2 calculate the number of H2O molecules formed when 39 C4H8S molecules and 287 O2 molecules react?

*February 5, 2010*

**trig**

In a diagram of circle, chords AB and CD intersect at E. If AE = 3, EB = 4, CE = x, and ED = x - 4, what is the value of x?

*February 1, 2010*

**trig**

A population of wolves in a country is represented by the equation p(t)=80(0.98)^t, where t is the number of years since 1998. Predict the number of wolves in the population in the year 2008.

*January 31, 2010*

**Calculus**

I think I am reading this wrong but this may not be a Calculus question. <= means less than or equal to >= means greater than or equal to Rates 20*x 0 < x < 50 20-0.02*x 50 <= x <= 600 When buying 1-49 articles, it is $20 per article. When buying 50-600 ...

*January 27, 2010*

**algebra**

eggs spear a mint

*January 27, 2010*

**Chemistry**

Please explain why benzophenone soluble in methyl alcohol. Thanks

*January 26, 2010*

**arithmetic**

The progression lists stops on the downtown 1 train in New York. The next number in the sequence is 14, but that's the last numeric stop. Try a real New York high school exam question: Complete the progression: 4,14,34,42,blank, blank.

*January 24, 2010*

**physics**

Two charges q = 3.0ì C are fixed in space a distance d = 4.5 cm apart. With V = 0 at infinity, What is the potential energy U of the three-charge configuration when the third charge is in place?

*January 23, 2010*

**physics**

PE=mgh

*January 23, 2010*

**physics**

2âˆš2...can someone tell me what that expression means

*January 23, 2010*

**physics**

haha oh ok thanks

*January 21, 2010*

**physics**

Bobpursley thanks for the help I see that Eq/m=a is equal to F/m=a but what vaule do I use for m in this problem

*January 21, 2010*

**physics**

A. A uniform, upward-pointing electric field E of magnitude 3.00 10e3 N/C has been set up between two horizontal plates by charging the lower plate positively and the upper plate negatively. The plates have length L = 4 cm and separation d = 2.00 cm. An electron is then shot ...

*January 21, 2010*

**Math**

y=50-5x x(1)=50-5(1)=45 x(2)=50-5(2)=40 try doing the rest

*January 21, 2010*

**physics**

sorry its theta=45 degrees for both questions

*January 21, 2010*

**physics**

A. A uniform, upward-pointing electric field E of magnitude 3.00~103 N/C has been set up between two horizontal plates by charging the lower plate positively and the upper plate negatively. The plates have length L = 4 cm and separation d = 2.00 cm. An electron is then ...

*January 21, 2010*

**Literary Analysis and Composition**

Thanks :D!

*January 21, 2010*

**chemistry**

Molar Mass for ammonia: 17.03 g/mol 1.852 g of ammonia is yield of crude product. 1.852 g ------- = 0.10875 mol 17.03 g/mol 0.10875 mol * 1 L ----- = 0.10875 L mol 0.10875 L * 1000 mL ------- = 108.7 mL 1 L

*January 21, 2010*

**Calculus**

line used for square = (40 - x) line used for circle = x Area = (area of square) + (area of circle) Area = (40-x)^2 + (pi*x^2)/4 Area' = (2)(-1)(40-x) + (pi*x)/2 = 0 x = 22.4 Is this max or min? Using x=20 for before the critical point, and x=30 for after the critical ...

*January 20, 2010*

**physics**

A. A uniform, upward-pointing electric field E of magnitude 3.00~103 N/C has been set up between two horizontal plates by charging the lower plate positively and the upper plate negatively. The plates have length L = 4 cm and separation d = 2.00 cm. An electron is then ...

*January 20, 2010*

**MATH213**

Calculators usually store more numbers internally than on the screen. Since you get 0.9998941, ask the student to subtract 1 from ANS. (If you don't have an ANS button, you can press the subtraction sign after pressing equal sign for the same effect as pressing "ANS&...

*January 20, 2010*

**MATH213**

The font didn't seem to process, so i did it in txt form again: a) sqrt(2*121) = sqrt(121) sqrt(2) = 11*sqrt(2) b) sqrt(144*2) = sqrt(144) sqrt(2) = 12*sqrt(2) c) sqrt(36*10) = 6*sqrt(10) d) not so sure about d... is nroot(162) a typo?

*January 20, 2010*

**MATH213**

a) ¡î(2*121) = ¡î121 ¡î2 = 11¡î2 b) ¡î(144*2) = ¡î144 ¡î2 = 12¡î2 c) ¡î(36*10) = 6¡î10 d) not so sure about d... is ©ú¡î a typo?

*January 20, 2010*

**physics**

Suppose that the attraction between the moon and the earth were due to Coulomb forces rather than gravitational force. What would be the magnitude of the charge required if equal but opposite charges resided on both earth and moon? Mass of earth = 5.98×1024 kg; mass of ...

*January 19, 2010*

**algebra 2**

its "a chew"

*January 14, 2010*

**social studies**

i need to write a 4 paragraph criteria essay on compare and contrast buddishm and hinduism on a 6th grade level

*January 13, 2010*

**gr.11 physics help!**

When an iceberg floats in the ocean, what fraction of it is visible?( The relative density of ice is 0.92, and the relative density of sea water is 1.03)

*January 6, 2010*

**adult education**

what type of language should you use in the invitation for a mechanical engineering professors?

*January 6, 2010*

**Pre-Calculus**

The Richtr scale was evied y Cahrles F.Richter a American geologist. The scale is based on the equation M(x)=logx/x0(little 0), where x is the seismographic reading of the earthquake and x0 i 1 miron 0.001mm (the seismographic reading of a zero-level earthuquake) a) Determine ...

*December 21, 2009*

**physics bobpursly help still having trouble**

A satellite in a circular orbit around earth with a radius 1.019 times the mean radius of the earth is hit by an incoming meteorite. A large fragment m=60 kg is ejected in the backwards direction so that it is stationary with respect to the earth and falls directly to the ...

*December 2, 2009*

**physics Bob Pursley plz help**

ok so I calculate PE when R is (1/1.019)*3.38e6 and then calculate Pe when R is just 3.38e6? Or are you saying multiple (Pe)(1/1.019-1/1)?

*November 30, 2009*

**physics Bob Pursley plz help**

A satellite in a circular orbit around earth with a radius 1.019 times the mean radius of the earth is hit by an incoming meteorite. A large fragment m=60 kg is ejected in the backwards direction so that it is stationary with respect to the earth and falls directly to the ...

*November 30, 2009*

**physics**

What is the pressure change in water going from a 3.0- cm-diameter pipe to a 1.8- cm-diameter pipe if the velocity in the smaller pipe is 3.0 m/s? Im using the equation pv2^2(A2^2-A1^2)/2A1^2 and get (1000)(3)^2(1.8^2-3^20/(2(3)^2) and get -2880 Pa but I'm getting wrong? ...

*November 30, 2009*

**algebra**

to find a percentage you do this X-number given Y-total number (X/Y)*100 so for example (25/50)*100= 50% you can also think of it this way 50*.50=25

*November 30, 2009*