Wednesday
December 7, 2016

Posts by bobpursley

Total # Posts: 42,724

Chem
Pressure is held down by attractive forces, so if they were suddenly repulsive, pressure would go up...if very repulsive, it could explode.
December 6, 2016

CHEMistry
Celcius, gram is abreviated by g, not G Pv=nRT PV=(.650/molarmass)RT convert Temp to Kelvins, then put in P, V, T, using R for ml,torr, and you will have the ability to solve for molarmass. Avoid using capital letters, it is difficult to read, and very unsocialbe (ITS SHOUTING).
December 6, 2016

Chem
moles. R is a constant. PV=nRT
December 6, 2016

Math
-197<-110 Think about the number line, and where you would place those numbers. More negative always means less...
December 6, 2016

Chemistry
you are diluting it 80/35 =2.29 times. (one part original, 1.29 parts water). So its new concentration : 2/(2.29) M=0.875M A more conventional method. In the stsock solution, you had .035*2 moles of NaOH. You have that same amount in the final dilution. Molarity=.035*2/.080=...
December 6, 2016

Math
f(-3)=-3(-3)+4=9+4=13 Are you certain that was the question?
December 6, 2016

Math
optimism; day length; optimism is a function of day length.
December 6, 2016

Math liberal arts 2
At least I didn't try to snow you with the auto-crosscorrelation coefficent, also used in signal processing (it is used in forward error correcting code processing).
December 6, 2016

Math liberal arts 2
Goodness. YOu can't figure out the answer a,b,c or d from what I gave you? I thought i put it on a silver platter.
December 6, 2016

Math liberal arts 2
there are many types of correlation coefficients, one of my favorite in Grad School (Information Theory) was the auto-correlation coefficient, used in signal processing.
December 6, 2016

Math liberal arts 2
Actually, "m" comes from the French Academy in the 1700's, from the French word to describe slope as we see it: m is short for the French word "montagne", or in English, Mountain.
December 6, 2016

Physics
If you want to do that, 3600sec/hr. However, the problem did not state the units of power. If you use Kw-hr, the problem is simple: energy=.1 kw * 2000hrs=200kw-hr
December 6, 2016

Math liberal arts 2
What is 3+16?
December 6, 2016

Science
They aren't. Lunar rocks are dated to figure out when the moon was molten and new. Same thing on Earth. Those tell us the age of the universe. Both indicate about 4-5 billion years old.
December 6, 2016

Math Question
greater than, less than.
December 6, 2016

Chemistry
http://www.speciation.net/Public/Document/2003/09/11/495.html Yes, use pH as the H+ species. Yes, like that.
December 6, 2016

geography
It runs exactly near the North and South Pole. Take a look at other locations. https://en.wikipedia.org/wiki/90th_meridian_west
December 6, 2016

Science
Here in texas, they often fall to the ground after collision... :)
December 6, 2016

The Simplex Method
If you want to do it manually, on graph paper, plot these lines: x+y=80 5x+10y=560 50x+20y=1600 x=0 ; y=0 The acceptable solution region will be on the border or in the enclosed area. But there is a nice theorem in Math that tells us the maximum will lie on the border, at one ...
December 6, 2016

Describing Data
add the deaths for 2006,2007,...2009, then divide by 4.That is the mean frequency, deaths per year.
December 6, 2016

physics
constant speed? friction=tension*cos25 but friction=mu(mg-tension*sin25) mu(mg-tension*sin25)=tension*cos25 solve for tension... tension(cos25-mu*sin25)= -mu*mg so you need to know the coefficent of friction mu to solve this.
December 6, 2016

Physics
a=(30-40)/time F=ma 10000=2000*aFromAbove solve for time t.
December 6, 2016

Language Arts (ASAP)
Why are all these Connexus students trying to cheat?
December 6, 2016

Science PLEASE HELP
Duh...a teacher's job is not to tell students the answers to important questions, but rather give them the skills and motivation to solve on their own. http://www.hk-phy.org/articles/maglev/maglev_e.html Write a paragaraph, and I will critique it. But a bad place will ...
December 6, 2016

Science PLEASE HELP
Why dont you write a paragraph, and I will critique it. This is not rocket science.
December 6, 2016

precalculus
Both are second degree equations, one is open, and one is closed. https://www.youtube.com/watch?v=pJmhLeUMABs
December 6, 2016

Chem
pressure decreases as altitude increases.
December 5, 2016

physic
depends on the speed of sound, which is mainly dependent on temperature and density of air. As a rule of thumb, 1225 km/h is Mach 1 in dry air, at 20C. But the actual speed of air varies with altitude (which affects temperature and density). Mach .2 would be .2 times the speed...
December 5, 2016

physics
Hmmmm. Is the tension just from weight of the wire? mg=magnetic force=I*L*B so I*B=mg/Length the direction of I depends on the direction of B.
December 5, 2016

Chemistry
molesHCl=.058*.13 you need mole of calcium carbonate 1/2 the moles of HCl
December 5, 2016

physics
1/4 lambda=.175 freq= velocitysound/lambda
December 5, 2016

Physics
The energy the diver had when hitting the water has to equal the upward force and distance in the water. mgh=force*distance h= force*distance/mg=1480*5.6/(55*9.8) meters.
December 5, 2016

comparing fractions
6/10;7/10;9/10;2/10 9/10;7/10;6/10;2/10
December 4, 2016

6th grade math
zero is a whole number. So I would look between -1 and zero.
December 4, 2016

Physics!!!!!!
see... http://www.jiskha.com/display.cgi?id=1317741181
December 4, 2016

Physics
wavelength= planck's constant/(mass*velocity) http://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Quantum_Mechanics/02._Fundamental_Concepts_of_Quantum_Mechanics/De_Broglie_Wavelength
December 4, 2016

physics
hf=29.9*sinTheta*time-1/2 g t^2 distance: 49.8=29.9cosTheta*time solve for time, put it in the first equation, and solve for final height, hf
December 4, 2016

History
It gave them a measure of freedom of Religion, and allowed them to worship in the open in a non-Roman Catholic way, in a Roman Catholic country. The Pope was not at all pleased with King Henry IV.
December 4, 2016

physics
distance: 4.4=4.3*cos17*time. Solve for time. final height hf=4.3*sin17*time- 1/2 g time^2 solve for hf.
December 4, 2016

English
Puritans = black shadow, grim, grisly, with a sword... Not the kind of person you invite to a wedding or a birthday party.
December 4, 2016

chemistry
balance the equation: 2C8H18+25O2 >>>16CO2 + 18H2O So for each mole of Octane you burn, you need 12.5 moles of O2 figure out the moles of octane you used, then multiply it by 12.5. then, multiply that by 32 to get the grams of O2
December 4, 2016

Algebra
D+N=28 10D+ 5N=195 Does that help?
December 4, 2016

science
Well, it will be national news if Miami discovers it is below sea level.
December 4, 2016

Science
depression=-.52*3.5*2 the molality concentration is 3*3.5*2
December 4, 2016

math help
Then the question should be "what is the smallest "whole number" that can be multiplied by 315 to make a perfect cube. (315*n) = perfect cube n=perfectcube/315 So for n to be a whole number, the perfect cube must end in 5 or zero just to satisfy the 5 rule. Now ...
December 4, 2016

math help
then 1/315 is the smallest number you can multiply 315 by to make a perfect cube.
December 4, 2016

math help
list of perfect cubes 1, 8, 27, 64, 125, 216, 343, 512, 729, 1,000, 1,331, 1,728, 2,197, 2,744, 3,375... Smallest number? multiply it by 1/315 and you get the perfect cube 1. Now I am not sure if your teacher really wanted the "smallest Number" that you should use as...
December 4, 2016

math
V=4000(1+.13 )^(160/365)== 4219.96015
December 4, 2016

P.E.
There are many, many types https://www.google.com/search?q=roller+board&source=lnms&tbm=isch&sa=X&ved=0ahUKEwic2rmUrtvQAhXH5yYKHRpIA6MQ_AUICSgC&biw=1200&bih=613
December 4, 2016

chemistry
you add two parts water to 1 part acid. Hmmmm. Actually, the wording on the question can be interpreted several ways.
December 4, 2016

PHYSICS HELP
P1/p2=t1/t2 p2=p2*T1/t2 p1=1e6*310/275=1.13e6 Pa
December 4, 2016

physics (urgent)
FIGURE THE MOLES OF GAS ORIGINALLY. N=pv/rt p,v,t GIVEN AFTER THE NEW TEMP, FIGURE THE MOLES remaining n'=Pv/T' so mass of gas escaped = 27(n-n') a) is done on the other post.
December 4, 2016

math
L*Price=504 (L+3)*(Price-4)=504 LP-4L+3P-12-504=0 next L=504/P 504-4*504/P+3P-516=0 now combine terms, and multiply by P -12P-2016 +3P^2=0 divide by 3, rearrange terms... P^2-4P-672=0 (P-26)(P-22)=0 So the at the higher price (26), he bought L=504/26
December 4, 2016

Physics
Ke original=PE at top +ke at top 1/2 m v^2=mgh +1/2 m (.6)^2 solve for h
December 4, 2016

Physics
H(x)=vi*t - 1/2 9.8 t^2 x=41.2 vi=27.5*sin44.9 now for t: d(x)=27.5*cos44.9*t but d(x)=41.2 solve for t, put it int the first equation, then solve for h(x).
December 4, 2016

Math
h(x)=0.5x-0.002x^2 h(x)=.5x(1-.004x^2)=.5/.004 * (x*(250-x^2) when x=0, x=15.81 (ie, sqrt250), height is zero. max height occurs at 15.81/2 feet downrange, figure that out from h(x)
December 4, 2016

physics
4*2000*g*mu=2000g*(27-0)/6 mu=27/4*6 b. torque=force*.3= 500g*mu*.3 c. change the 4 to 2.
December 4, 2016

Physics
If it is going up at constant speed, then pushing force-gravityforce-friction=0 pushing force=mgSinTheta+600N That is the net pushing force on the car
December 4, 2016

Physics
determine max speed from maxKE=maxSpringPE for max acceleration 1/2 m v^2=1/2 kx^2 2v v'=2kx v v' acceleration=kx/m period=2PIsqrt(mass/k) and freq= 1/period
December 2, 2016

Physics
"Do it step by step and then substitute the numbers into that equation " You are kidding.
December 2, 2016

Algebra 1B
set the equations equal (both equal y) 3x+20=x^2+2x x^2-x-20=0 (x-5)(x+4)=0 solutions at x=5, and x=-4 Now put those solutions into either equation, and you have a x,y set. y=x^2+2x (-4,8) and (5,35) are the two solutions.
December 2, 2016

Surface areas and volumes
area=depth*PI*2r cost=cost/m^2 * area
December 2, 2016

Math
v=5*8/3 *15 liters
December 2, 2016

Physics
.01 mole= .01*Avagnumber*e = .01*6.02E23*1.6E-19 coulomb = about.1E4 coulomb in my head
December 2, 2016

PHYSICS (PLEASE HELP ME ASAP)
change temps to Kelvins P2V2/T2=P1V1/T1 a) solve for V2 b. pv=nRT change V to m^3 (22.4E-3) R=PV/nT=101325*22.4E-3/(1*273)=... c. PV=nRT n=PV/RT
December 2, 2016

Physics
potential energy.
December 2, 2016

MATH ASSIGNMENT
stop posting your homework under multiple names....
December 1, 2016

MATH ASSIGNMENT
12,000=P(1+.0615/12)^(7*12) take ln of each side... ln(12000)=lnP + 7*12*Ln(1+.0615/12) lnP=ln(12000)-7*12*ln(1+.0615/12) pasting this into the google search window: ln(12000)-7*12*ln(1+.0615/12)= 8.963 so P= e^8.963=7808
December 1, 2016

linear programming problem
There is no way we can work this in ASCIii, so here is an example in detail: http://math.uww.edu/~mcfarlat/s-prob.htm
December 1, 2016

MATH
46000=P(1.0755)^12 take the ln of each side ln46000=ln P+12ln(1.0755) lnP=ln(46000)-12ln(1.0755) using the google calculator in the google search window: ln(46000)-12ln(1.0755)=9.86296864 than taking the antilog, P=e^9.86296864=19206 about
December 1, 2016

math
(x-4)(x-1)=0 x=4, x=1 are solutions
December 1, 2016

Finite Math
Do this graphically: Let the y axis be Model A, x axis Model B. Now consider cast iron. On the Y axis, mark the point 0,333 (the point of all model A and all the iron). then on the x axis, mark 250,0 (all cast iron used on B). connect the points, that is the IRON constraint ...
December 1, 2016

Algebra 7th grade
b. .25x+3<=10 as he can spend all ten dollars.
December 1, 2016

Finite Math
amount=5000(1+ (i/n))^(t*n) where n is the number of compounds per year, and t=9 for instance, for n=12, put this in your google search window: 5000(1+(.075/12))^(9*12)= And the answer pops up 9799.56
December 1, 2016

Is My Answer Correct Tutors?
correct.
December 1, 2016

Health
ok, but the ones I have seen list STAT, urgent, routine.
December 1, 2016

Astronomy, Math, Science
what is 7*tangent33?
December 1, 2016

Chemistry
Normalityacid*volumeacid=Normalitybase*Vb vb=.15*3*25ml/.1=4.5*25ml
December 1, 2016

physics
h=1/2 g t^2 t= sqrt(-100*2/(-9.8)) vf=-9.8*time
December 1, 2016

Physics
v^2/(re+h)=9.8(re/(re+h))^2 v^2=9.8*re^2/(re+h) v^2=9.8* (6.37E6^2/(6.37E6+ 3.7E7) v^2== 9168863.73 v=3028 m/s rounded to three sig figures is 3030m/s If I had used 9.81 for g...
December 1, 2016

physics
avg velocity is 15m/s, for five seconds d=v*t
December 1, 2016

chemistry
in moles a=2.5, b=3E24/6E23=5moles, c=1.5moles
December 1, 2016

Herzing
Thanks. What is your question? How long does it take both to paint a wall? sue can do 4walls/hour, and Joe can do 6walls/hour Together they can do 10 walls/hour, so together, it takes them .1hr to do a single wall
December 1, 2016

SCIENCE-CHEMISTRY
density=mass/volume mass=density*volume=5.6kg/L*.3^3 L mass=5.6*.027 kg= 0.15kg
December 1, 2016

physics
Physics?
December 1, 2016

SMCT Physics
64+38cos65 + j38sin65 80+j34.4 angle from the larger: arctan34.4/80 magnitude=65/cos(arctan34.4/80)
December 1, 2016

Algebra
greater than 3 means 4,5,6 the Pr(greater than 3)=3/6 pr(both greater)=1/2 * 1/2 = .25
November 30, 2016

chem
P1*V1/T1=P2*V2/T2 P1= P2*V2*T1/(T2*V2) change temps to kelvins, then get your calculator out.
November 30, 2016

Science chemistry
in one mole of N2O4, there are moles of N2: one moles of O2: two Your work makes no sense, and is off on a tangent.
November 30, 2016

physics
There are two forces here: gravity down the slope: mgSinTheta friction up the slope: mg*mu*CosTheta at constant velocity, these are equal. b. friction will be greater than gravity...so it has the initial velocity, so net force up (friction-gravity)*times distance must equal ...
November 30, 2016

Chemistry
first look at solubility: NaCl...two particles per molecule CaCl2..three particles per molecule C2H5OH...does not break up, one particle per molecule Na3PO4...four particles per molecule. Now, mulitily the original given concentration by the number of particles that results ...
November 30, 2016

biology help
what is a Prokaryotic Cell?
November 30, 2016

Science
Each has only 1/2 the DNA required of a living cell, so to unite means a new living cell. factors: a vector to transport the male cells (ie, wind, insects, ) Temperature, presences of insects, wind are factors.
November 30, 2016

physics
wf=alpha*time where alpha=torque/momentinertia = 5.5*.36/(1/2 *4*.18^2) wf will be in rad /sec. to get rpm RPM=wf/2pi * 60/1=30wf/PI
November 30, 2016

Science
a, and c are true.
November 30, 2016

Chemistry
for the first three, one wonders. How much (in grams, moles, or else) was invovled in the reaction? 1gram, or 200 tons? mole ratio of Al to O2: 4::3
November 30, 2016

MATH
3xy-y^2=2 2x-3y=-4 from the second, x=-2+1.5y putting that into the first 3(-2+1.5y)y-y^2=2 -6y+4.5y^2-y^2=2 3.5y^2-6y-2=0 y^2-21y-7=0 check my work quadratic equation.. y=(21+-sqrt(21^2+28)/2 y=(21+-21.66)/2 y- 21.33, or y=-.33 then calculate x for each. CHECK ALL THIS, I did...
November 30, 2016

physics
It went .48m in .505 sec v=.48/.505
November 30, 2016

Math
shifting to polar.. 3+i= sqrt10 @arctan(1/3) on the complex plane so (3+i)^5=(sqrt10)^2 @5*arctan(1/3) and that is 100sqrt10 @5*18.4349488deg 100sqrt10 @92.17 deg converting back to complex plane real+ imag where real=100Sqrt10*cos91.17 imag=i*100sqrt10*sin91.17
November 30, 2016

Algebra
Here is how to type it. The sum of (-1)^k +1.5k from k=1 to 8. for eight terms, you can do this with your calc k termvalue 1....0.5 2....4 3....3.5 4....7 5....6.5 6....10 7....9.5 8....13 See the pattern: each even add three to the previous even, and for the next odd, ...
November 30, 2016

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