Friday
July 29, 2016

Posts by bobpursley

Total # Posts: 41,502

Maths
You need to clarify: is sin2a sin^2(A) or sin(2A)? is cosC/2= cos(C/2) or 1/2 Cos C?
July 28, 2016

General Chemistry
Kc=[Pb2+]*[2*Cl-]^2 Kc=1.6E-2 * 4*(3.2E-2)^2
July 28, 2016

Science
force=pressure*area=50N/m^2*600cm^2*1m^2/(100cm)^2 force=50*600/10,000=30,000/10000=3N
July 28, 2016

Science
d=1/2 a t^2
July 28, 2016

Physics
draw the figure. you have all angles of the rays to the normal. You have the triangle (with angle and opposite side of 1mm), so figure one other of the interior angles of the triangle from the sketch, then use the law of sines to figure the distance of one of the paths. I ...
July 27, 2016

Math
12/16=3/4 or 3:4
July 27, 2016

Physics
PE lost=KE gained mgh=1/2 mv^2 + 2/3 M r^2*w^2 where w=v/r gh=1/2 v^2+2/3 v^2 solve for h.
July 27, 2016

Science
six million years ago is a good estimate. No one wrote it down.
July 27, 2016

Science
http://humanorigins.si.edu/education/introduction-human-evolution
July 27, 2016

Science
There is no answer to this, as "humans" are evolved, and are still evolving. When did the first catfish appear? There is no answer.
July 27, 2016

Chemistry
http://ppm.rxisk.org/MedGuides/Vicoprofen/vicoprofen-tabs-smallstructure2.jpg
July 27, 2016

maths
speed=distance/time 60=d/2time1 but d=60*time1+V*time2 and 80=d/(time1+time2) or time1+time2=d/80 then d/120+time2=d/80 time2=d/80-d/120=d/120 (3/2-1) time2=d/240 so velocity2ndpart=(d/2)/time2 = d/2(d/240)=120km/hr check: time1=d/(2*60)=d/120 time2=d/(2*120)=d/240 80=d/(time1...
July 27, 2016

Math
tan16=h/300 or h=300*tan16 tanTheta=h/(225) put in h, then determine tan theta, then theta=arctan(h/225)
July 27, 2016

Algebra
midpoint of segment should be (-7.5, 2.5)
July 27, 2016

Physics
bouyancy= densitywater*volumebody = 1g/cc*100cc=100g weight after immersion=700-100
July 27, 2016

Maths
18x51=.24Area = .24*D*51 solve for D, then dimensions of original back yard is Dx51
July 27, 2016

Urgent Math
percent= 4/54 * 100
July 27, 2016

Math help
decrease=5/14 * 100 percent
July 27, 2016

Physics
see other post
July 27, 2016

Chemistry
v=62 log(10)=62 millivolts?
July 27, 2016

Chemistry
ionic, small chain alcohol, long chain alcohol, and alkane least soluble.
July 26, 2016

microsoft PP
a is the best of the four, however, your audience (age, experience, interest) is much more important than their location.
July 26, 2016

trig
cosTheta=1/secT=-3/20 so Theta is in the second, or third quadrant. If Theta is in the second quadrant, the sine is positive. If in the third quadrant, sine is negative. cos^2 t= 9/400 sin^2 T= 1-9/400= 391/400 sinT= +- sqrt(391)/20 TanT = sinT/cosT= second quadrant=-sqrt(391...
July 26, 2016

physics
upward motion: h'=vi*t=1/2 * 9.8 t^2 h'=20, vi=30, solve for t using quadratic formula now with t, v=vi-g*t, put vi=20, and t from above, and you have v. Max height: initial KE=final PE 1/2 m vi^2=mgh solve for h, the max height. Velocity just before landing = negative...
July 26, 2016

chemistry
Normality=Heq*M= 1* 50/molemass*1 molemass NaOH is 40 is I remember, check that.
July 26, 2016

physics
max speed: v=at=1.5*20=30m/s distance covered during acceleration: d=1/2 a t^2=1/2*1.5*400=300m constant speed: distance covered d=30m/s*20s=600m total distance=300+600=900m
July 26, 2016

Chemistry
It depends on the conc of the phosphoric acid.
July 26, 2016

physics
vf^2=2ad 80^2=2*4*d solve for d. if takeoff speed is 1/2, then the distance is (1/2)^2=1/4 as far
July 26, 2016

Pyshics
triple the speed, increase distance by 9x distance=9*30 reason: work done=KE friction*distance=1/2 m v^2 so distance is proportional to v^2
July 25, 2016

Chemistry
none, unless you decompose it. With this equation 2KClO3>>>2KCl + 3O2 for each mole of KClO3, you get 1.5 moles O2. you started with molesKClO3 as 120/molmassKClO3 multiply that by 1.5 to get moles O2 multipy then by 32 to get grams of O2
July 25, 2016

MATHEMATICS
Not completed percent: (b and girls not doee)/(b+g) (.65g+.55b)/(b+g) (.65g+.55*3g)/(3g+g) g(.65+1.65)/(4g) 2.2/4=.55 or 55 percent not done
July 24, 2016

Physical Science
lambda=speedlight/frequency.
July 23, 2016

physics
well, you know the conservation of momentum applies. Take teh ball B, the North momentum, so BAll A must have that same momentum in the S direction as there was no initial N-S component. Then, take BAll B East momentum, subtract that from BallA initial East nomentum, so that ...
July 23, 2016

Small Business Management
http://www.more-selfesteem.com/selfimage.htm
July 23, 2016

physics
conservation of momentum applies .016*V=(.016+4.550)*1.2 solve for V
July 23, 2016

Probability
another method: Pr(1 or more)=1-Pr(none rotten) pr(1 or more)=1- 56/60*55/59*54/58 = 0.189947399
July 23, 2016

math
abx-ac=d-x-e ab=-1 which immediately poses a problem, because either a or b is negative, which is <0, and the problem stated both were >0
July 22, 2016

Math
wondering the location of b.
July 22, 2016

general math
If distance is greater then 4km, then Cost= 8+1.5(distance-4.0)
July 21, 2016

Science
I would ask for another science teacher, this is not science. You deserve a quality education if you are paying for it. Teachers who give these to you as course work are wasting your time, in my opinion.
July 21, 2016

chemistry
Both are moniprotic. However, you need to know what volume of lye is being used., and the concentration of the oxalic acid.
July 21, 2016

physics
consider two pistons, A and B ForceA/areaA=forceB/areaB in your case, AreaA/AreaB = 10 as I read it.
July 21, 2016

Physics
First of all the "current" for the right hand rule is positive current carrent carriers, mythical as they are in a wire. Put your thumb in the direction of positive current, then curl the fingers, that is the direction of the surrounding magnetic field. Now, on ...
July 20, 2016

Math
maybe Scott is right, you meant (r^2+5r+6)/(r+2 ) it is difficult to solve these if the function is not written with precision
July 20, 2016

Math
I think the problem is supposed to be this: f(r)=r^2+5r+6/(r+2) obviously, r cannot be -2. Try -3. This problem is not rocket science. Plug in the values and compute
July 20, 2016

Physics
period will be shorter...gravity on earth is stronger, and it pulls the pendulum down faster. period=2PIsqrt(Length/g)
July 20, 2016

Physics
potential is a scalar, you can add the potential from each point charge.. V=kq(1/d+1/d) E is a vector, so you have to add as vectors. The are 60 degrees apart. Draw a sketch, you will see the resultant splitting the 60 degree angle, with the side componets adding to zero. E=...
July 20, 2016

science
And what about family history, esp mom and dad?
July 20, 2016

physical science
of what choices? Did you do an experiment?
July 20, 2016

college physics
left wing.
July 20, 2016

physics
This makes no sense
July 20, 2016

Physics
https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.ytimg.com%2Fvi%2FlVBymD0TyaM%2Fhqdefault.jpg&imgrefurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DlVBymD0TyaM&docid=uu8WzLsazrTYjM&tbnid=ap9UiYUSNX-PeM%3A&w=480&h=360&bih=368&biw=720&ved=0ahUKEwj-...
July 16, 2016

Physics
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/imggo/raymir.gif https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcT4fTOd46EYralXaqhpkJSx0faUxgY8YFlDr3nwVeO4aQ8oxj4f
July 16, 2016

numeracy
20 min per trip :(15 min + 2.5 load+2.5min unload=20min
July 16, 2016

numeracy
well, round trip is just part...what about loading/unloading time? Assuming 2.5 min to load 36 passengers, assuming none trips.. each vehicle can make 90/20=4 trips (if you assume a silly zero time to load and unload, 5 trips. 1134/36=32 trips number cars=32trips/4 trips/car...
July 16, 2016

physic
Actually, you dont need the coefficent of friction, you need the distance he slid, or the time. Vf^2=vi^2 + 2ad but a=forcefriction/mass and if you knew distance d, you could solve for forcefriction
July 16, 2016

Physics
The problem is really worded poorly. It is asking if two objects are dropped at slightly different times, how does the length between them vary with time. distancefirst=1/2 g t^2 distancesecond=1/2 g(t-T)^2 distance L= distancefirst-distancesecond = 1/2 g (t^2-(t-T)^2)=L so ...
July 15, 2016

physics
A+B=-4j -3i+2j+B=-4j B=3i-6j
July 15, 2016

PHYSICS--
fsumnew=16*(1.5-1)/(1.5-1.33) = 16(.5/.17)= 47 cm and because the diatance between the lenses is the sum of the two focal distances, that is the new distance.
July 15, 2016

Calculus
u= sin^2(z) u'=2sin(z)dz/dt=2sin(cost)*(-sint) and you are correct.
July 14, 2016

physics
hf=hi+1/2 gt^2 hf=0 hi=25 t=2.26 g=-25*2/2.26^2
July 14, 2016

Chemistry
as did I.
July 14, 2016

homework
and if you are unfamiliar with log equations, take the log of each side.. t*log1.039=log2 t= log(2)/log(1.030 and put this into your google search window log(2)/log(1.030) = and it is about 23 hours...
July 14, 2016

Science
weight=300*.38 N Mass=300/9.8 kg mass does not change...
July 14, 2016

pharmaceutical physical chemistry
PV=nRT where n= moles= mass/molemass=mass/17 PV*17=mass*RT mass/V=density=Pressure*17/RT Now look up the gas constant R, watch units carefully. Temp is in kelvins. pressure in Torr, mass is in grams. Carefull with units
July 14, 2016

physics
You can draw a figure, and use the law of cosine/sines or.. figure components then add. first day: N: 25cos135 N (angles from 000 clockwise) E: 2sin135 E second day N: 40cos30 N E: 40sin30 E Now add components: N: 40cos30 + 25cos135 E: 40sin30 + 25sin135 Now, displacement.. d=...
July 14, 2016

Chemistry
2H2S+SO2>>> 2H2O+2S for each 2 moles of H2S, two moles of S are produced. moles of H2S=125/34 so, you should get the same number of moles of S, or grams S=125/34 * 32
July 13, 2016

math
3 + 27/1000 three and twenty-seven thousandths
July 13, 2016

Economics - PLEASE HELP
Of course not. Have you tried reading the text? guessing is silly, and a waste of time.
July 13, 2016

Economics - PLEASE HELP
1. Nope, it asks for MAIN advantage. 3. Arguable, but yes, however, cost of starting some is great. 4. variable costs increase as volume goes up.
July 13, 2016

physics
initial vertical velocity: at the top, vf in vertical, is zero. so in the vertical, vf^2=vi^2+2ad 0=vi^2-2*9.8*10 vi=sqrt(2*9.8*10) so v=sqrt(vi^2 + (1/2 vi)^2) v=2*9.8*10 sqrt(1+1/4) = 2*9.8*10/2 sqrt 5 time in air: vf=vi+at 0=sqrt(20*9.8)-9.8t solve for t then knowing t, ...
July 13, 2016

English composition
Correct you? You haven't written an essay yet.
July 13, 2016

Physics
w=2PI*f Xc=1/(2PI*f*C)
July 13, 2016

science
Let me get this straight: you are starting with salt water, and you want to get a more concentrated lye solution? Goodluck.
July 13, 2016

History
Yes, as the US had not entered the war, the US tried negotiatinos with the Vichy Government. https://www.quora.com/How-come-the-Vichy-regime-received-so-much-support-during-the-World-War-2-in-France
July 11, 2016

Math - Transformations
try changing it to this: g(x)= -2(8)(x-2)^3 -1 = -16(x-2)^3 -1 does that change your analysis?
July 11, 2016

Physics
if the current increased 5 times, that means the new resistor of 400 ohms is carrying 4 times the current as the original resistor, which means the original resistor has to be 4x as much, or 1600 ohms. Scott is right.
July 11, 2016

physics
distance=speed*time time= distance/speed 30 min= 1/2 hour for the last one.
July 11, 2016

Physics
It depends on the shape, and what the area represents? Base? total area? does the object have volume?
July 11, 2016

science
pepto bismol, milk, solutions are clear, if it is a cloudy liquid, it is a suspension.
July 11, 2016

PHYSICS
and of course, the final KE is equal to the initial PE... initial PE=mgh=2*9.8*3=58.8Joules
July 10, 2016

think mathematically
1,2,3,4,5,6,7,8,9,10,11,....
July 9, 2016

CHEMISTRY
2HCl + M2CO3 >>> 2MCl + CO2 + H2O So you reacted (25/1000)*7.46 grams of the carbonate, with .027*.1 moles of acid. from the balanced equation, then the moles of M2CO3 is 1/2 * moles acid=1/2*.027*.1 figure that out. Now you know (or can figure) the molmass of the ...
July 9, 2016

Pre-Calculus 11
Ok, I can't read your symbols.
July 9, 2016

Physics
Well, as you wish, but I suspect if you posted your WORK, it would be solved very quickly what the issue is.
July 9, 2016

Physics
post your work, let me see what you are doing.
July 9, 2016

Physics
Anna, I showed you a correct solution, in JOULES. If you want the obsolete unit of calories, then just use the specific heat of water in calories (1 cal/gram per degree C), instead of 4.18 J/gC. Or, you can convert the answer in Joules to calories (4.18J=1calorie).
July 9, 2016

Math(HELP PLEASE )
x+y=2 3x+3y=6 divide the second by 3 x+y=2 same as line 1. Coincident. Not solvable.
July 9, 2016

Pre-Calculus 11
I can't read it.
July 9, 2016

Physics
period=2PI*sqrt(l/g) 3.9=2PI*sqrt(1/g) square both sides. 3.9^2/(2PI)^2=1/g g=(2pi/3.9)^2
July 9, 2016

Algebra
Yep, it is wrong. ln y(y+1)^5 lny + 5ln(y+1). so I dont know where that is in, or has to do with this. y^5ln(y)+5y^4ln(y)+10y^3ln(y)+10y^2ln(y)+ln(y) ... Are you treating this as (Y+1)^5 *lny ? I don't think that is what was intended, my guess the intended expansion is ln...
July 9, 2016

Physics
heat gained by water: masswater*specificheat*deltatemp 200g*4.18j/g*(27.2-20)=... heat gained by water+heat change by metal=0 above heat calculation+95g*cmetal*(27.2-98)=0 solve for cmetal
July 9, 2016

COM 425
And, it could be 1.
July 9, 2016

science
You want a 40 percent solution. Now you have two sulfuric acids: 100L of 20 percent and X liters of 98 percent sulfuric acid. I am wondering which sulfuric acid you want to use to make the 40 percent solution. in the 100l, you have 20 liters of sulfuric acid. You will need a ...
July 9, 2016

physics
period=2PI sqrt(g/length) so the period on the moon will be sqrt(1/6) that of the period on Earth.
July 9, 2016

CHEMISTRY
What exactly is x?
July 9, 2016

geometry
and more..?
July 9, 2016

PHYSICS
yes Pythagorean theorem 302^2=300^2 + V^2
July 9, 2016

RIFT VALLEY UNIVERSITY COLLEGE
Greetings to Ethopia. Your question does not make any sense.
July 9, 2016

Math
I am wondering where is the end of an axis, all those I draw have no ends. x axis is not a line segement. What do you mean by the end of the axis?
July 9, 2016

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