Thursday
March 23, 2017

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Posts by bobpursley

Total # Posts: 44,134

Chemistry
B is correct.
March 22, 2017

Math
Well, if blue probility is .2, then red has to be less, so if pr<.2, that is a valid probility for red.
March 22, 2017

Physics
Adapt this problem to your problem: I do not understand your picture, but this should guide you. https://www.physics.wisc.edu/undergrads/courses/spring09/248/HWSolutions/HW12Solutions.pdf
March 22, 2017

Ethics
It is the question. Consider the biblical story of the Good Samaritan. How many passed by the injured and beaten man before the good samaritan provided for his care? Consider what Doctors without Borders tries to do, and the impediments put in their way. Consider Medicaid and ...
March 22, 2017

Algebra
Isn't it proved by definition? The angle whose sine is the sine of theta, is theta.
March 22, 2017

physics
the average velocity is 1rev/second, it want for 30 seconds, displacement=avgveloicty*time=30rev
March 22, 2017

calculus review please help!
Mean Value Theorem for Integrals. A variation of the mean value theorem which guarantees that a continuous function has at least one point where the function equals the average value of the function. Mean value= (f(1)+f(-1))/2 = (-8+8)/2=0 if f(x)=0=x^3-9x, the the one point ...
March 22, 2017

Physics
http://www.jiskha.com/display.cgi?id=1490218992
March 22, 2017

chem
constant pressure... V1/V2=T1/T2 .67/1.12=(61+273)/(273+Tc) solve for Tc , the celcius temp for the new volume.
March 21, 2017

Chemistry
moles Al=.5/27=.0185 Moles CuCl2=3.5/134.5= 0.0260 the balanced equation requires 3/2 moles CopperIIChloride/Al you have .0260/.0185=1.20 so you dont have a 1.5 ratio, you have too little CuCl2, and it is the limiting reactant
March 21, 2017

Science
constellations in the North Sky and South sky may not always be visible because of Earth tile and latitude from which observed.
March 21, 2017

Physics
vfinal=vinitial+at you have given vinitial, acceleration. You want the time t. So what final velocity are you aiming for, vfinal?
March 21, 2017

MATH
6.5m*100cm/1m=your answer is wrong.
March 21, 2017

Maths
3. 63-17+19=?
March 21, 2017

English
That is a rather lengthy topic...I suggest you narrow it.
March 21, 2017

child development
and the following guidances are...??? If one can, ignore largely the negative behaviours and reinforce the positive behaviours.
March 21, 2017

Chemistry
Mr????? Do you mean the molecular mass? I assume so. it is 44amu, or 44 grams/mole CaCO3 >>>> CaO + CO2 moles CaCO3= 1000g/(100g/mol=10moles so according to the balanced equation, you should get 10 moles CO2, or 440 grams.
March 21, 2017

Calculus
<<Cross sections of the solid perpendicular to the y-axis are semicircles>> Somehow, I am not visulizing this. so the base of the solid is in the xy plane, so its altitude must be in the k direction. For the k direction to be semicircles, the shape of the solid has...
March 21, 2017

Calculus
What is this x-5+5?
March 21, 2017

english Grammar
Matt likes fish
March 21, 2017

Maths, dynamics
x=INT v(t)dt =5/6*t^6 i + 4/6 t^6 j + 1/4*t^4k+C given t=0 x=i+2J i+2j=i(5/6(0)+2/3 (0)j+Ok+C C=i+2j
March 21, 2017

Maths, dynamics
F=Ma a=F/m=225/45 t^4-90/45 t^2-225/45 a=5t^4-2t^2-5 v=int a(t)dt =t^5-2/3 t^3-5t+C given at t=O, v=2 C=2 if v=t^5-2/3 t^3-5t+2 then x=INT v(t)dt x=1/6 t^6+1/6 t^4 +2.5t^2+2t+C given x(o)=6 implies then C=5
March 21, 2017

Trigonometry
if sinx=-1/2, then cosx=sqrt(1-1/4)=sqrt(3/4)=sqrt3 /2 sin(2x)=2*(-1/2)(sqrt3 /2) = -1/2 sqrt3
March 20, 2017

Trigonometry
1/ctn=tan=sin/cos=sin/(1-sin^2)
March 20, 2017

SCIENCE
correct, however, these days news comes on and I have a strong desire to bounce my TV off the wall, number 3 :) .
March 20, 2017

Chemistry
Increase.
March 20, 2017

Art
1.)Inventors often work to find faster, more efficient ways of completing a task. How did Samuel F.B. Morse use his artistic ingenuity to create a more efficient telegraph machine? He used only one wire....
March 19, 2017

chemistry
moles NaOH=.015*.1=.0015moles Moles HCl=.025*.1=.0025 moles excess acid= .0010 moles concentration=.0010/.040 moles/liter pH=-log(H+)=-log(.025)=1.60 pretty acidic
March 19, 2017

chemistry
NH3? PV=nRT n=PV/RT mass/molmassNH3= PV/RT solve for mass. change temps to Kelvins, and use R in the units of mmHg*Liters/Kelvin
March 19, 2017

physics
if the "apart" is from center to center distance, .25=kqq/.4^2 solve for q Coulomb's law
March 19, 2017

science
greater at the higher elevation.
March 19, 2017

physics
momentum is conserved. 3*5+8*(-3)=(3+8)V V=(15-24)/11=-9/11
March 19, 2017

Chemistry
you are dreaming thinking you can dump homework here.
March 19, 2017

chemistry
Heat=mass*specHeat*changeinTemp Notice you are given specific heat in J/gK. the same value applies with units kJ/kg-K
March 19, 2017

math
multiple of three:3 or 6 pr (3or6)=2/6=1/3 pr(not 3or6)=1-1/3=2/3
March 19, 2017

ELECTRICITY AND MAGNETISM
Vt=k(q1/3+ q2/4)
March 19, 2017

ELECTRICITY AND MAGNETISM
let the distance from P to each charge be d1,d2 energy=kq3(1/d1+1/d2)
March 19, 2017

College
what is sqrt ( 450^2+725^2)
March 18, 2017

Algebra
126=M(.03)+(4000-M)*.04) where M is at 3 percent. 126=m(.03-.04)+160 M= 34/.01= 3400 and 4000-M=600
March 17, 2017

calculus
it is of the form inf/inf. taking the derivatives. it is not clear to me is the +1 in the exponent or not, I assume not. lim= (5)/(5))*(4x)(5) lim= 1^inf * 5=5
March 17, 2017

calculus
you do have a 0/0 form Using Hospital's rule then lim= (e^x+e^-x-2)/(x+cosx) Lim= 0/1=0
March 17, 2017

physics
let tension right and left=Tr,Tl Tr+Tl=69*g now sum of moments about the right end.. 69g*2.8+Tl*12.5=0 solve for Tl in that equation, then go back to the first equaion, and solve for Tr
March 17, 2017

Chemistry
Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq)
March 17, 2017

PHYSICS
KE at impact=PE at start= m*g*h
March 17, 2017

Physics
is this positive charge current, or electron current? It matters. Us your hand rules in your text.
March 17, 2017

Physics
the type of charge, its direction,and direction of the magnetic field. Does your text show you right hand,left hand rules? Surely it does.
March 17, 2017

Physics
surely your text answers these questions....
March 17, 2017

Physics
oops, you should have caught my error. You reduced distance by 1/2, so B is twice or .2T
March 17, 2017

Physics
B=k I/r so if you reduce r by a factor of 1/10, B is now x10, or 1 Tesla
March 17, 2017

chemistry
balance the chemical reaction Mg + 2HCl>>>H2 + MgCl2 so you need the same number of moles of Mg as you get in H2. molesH2=100/2=50 moles molesMg=same gramsMg=atomicmassMg*50=24.3*50 grams.
March 17, 2017

Algebra
John has to be 16. Something is wrong with the sentence, punctuation?
March 17, 2017

science
You typing makes we wonder i i i force is inversley prop 10E-5/F=( 3^2/20^2) F=400/9 E-5 N at 3 cm one 100 cm,that is 5 times as far.. F=1E-5 /25=4E-7 at 100cm
March 17, 2017

Physics
resistance=Ro(1+.0047T) Ro=10 ohm, given check: R@100=10(1+.0047*100)=10(1+.45)=15ohm 30=10(1+.0047T) 3=1+.0047T T=2/.0047=426C
March 17, 2017

Math
if those are absolute value signs, then all have to be positive,answer B. However, it is a confusing question.
March 16, 2017

Math7/8
with replacement Pr(R,R)=3/8*3/8 without replacement Pr(R,R)=3/8*2/7
March 16, 2017

algebra
.45V1+.90(120-V1)=.6*120 solve for V1, then 120-V1
March 16, 2017

chemistry
I assume your m should be Molarity, M. mass=molartiy*molmass*volumeinLiters mass=.1*molmassBenzoicAcid*.1m^3 so the mom mass is 122g/mole, so we have mass=.1 Mole/liter*122g/mole*.1 Liter= 1.22 grams check my thinking.
March 16, 2017

Language art 4th grade
got or gave. Answer D.
March 16, 2017

Algebra
Do you do matrix algebra on your calculator? coats, shirts, dresses, cost in augmented matrix form: 5,5,6,77 1,8,6,67 3,3,2,43 Now if you want to do it manually as a 3x3 set 5x+5y+6d=77 and so on, then solve it with pencil and paper. The augmented matrix is much faster..
March 16, 2017

Physics
displacement: 860*.75-720*1.5 East distance : add the above avgvelocity=displacement/total time avg speed: distance/total time
March 16, 2017

health class
true.
March 16, 2017

physics
effort=1/.8 * 50*9.8*k what is k? that is the mechanical advantage, it will depend on how the pulleys are connected. In this case, the k probably equals 5, but one would have to look at it. https://www.khanacademy.org/science/physics/work-and-energy/mechanical-advantage/v/...
March 16, 2017

physics
see other post.
March 16, 2017

physics
http://www.wikihow.com/Calculate-Terminal-Velocity
March 16, 2017

Science
I will be happy to critique your response.
March 16, 2017

math
this makes no sense to me.
March 16, 2017

chemISTRY
v_rms = sqrt(3RT/M) where M is the 28 for N2, and 4 for He
March 15, 2017

Math
50/125=xxxx xxx=2*25/(5*25)=2/5=.4=40 percent
March 15, 2017

math
180=.75*P P=180/.75=240
March 15, 2017

MATH
you need the bases first. draw the sketch. label the top base a, the bottom c. now notice on c, it is longer than a by 2*k, where k is the length of the base below end triangles. Pyth: (c-k)^2=25^2-15^2 or c-k=20cm but c=a+2K Now the median length: median=(a+c)/2=(c-2k+c)/2 =...
March 15, 2017

Science
yes
March 15, 2017

AP Physics
frictionless? think on the spool, would it rotate? it has a force on it (either above the cg or below, I dont have a picture), but would it rotate? I suspect your teacher wants you to consider a mimimal friction...
March 15, 2017

World History
C is a good answer, however, I would have wished ethnic hate would have been listed. Austria-Hungary had just annexed Bosnia-Herzegovin provinces a few years earlier against the wishes of neighboring Serbia, which likewise coveted them. Ferdinand believed the Serbs to be “...
March 15, 2017

Science
acceleration=changebelocty/time= 145.08/4.48 m/s^2
March 15, 2017

Maths
a liter is a dm^3 v=(d/2)^2PI*h=3.5^2*PI m^3 v=3.5^2 *PI (10dm)^3 because 1m=10dm v=3.5^2*Pi *1000liters
March 14, 2017

Physics ( oscillations and waves)
f*lambda=speed lambda=2*60=1.20m speed=30*1.20 m/s
March 14, 2017

answer!
The height h thru which it will fall is H=11.50(1-cos39) 1/2mv^2=mgh v=sqrt(2gh) exclamations points are to me a bit exaggerated.
March 14, 2017

physics
force=k*x=60N/m *.016m
March 13, 2017

physics
f=kx=230N/m * .08m
March 13, 2017

Physics
RE=1/2 *I w^2=.5*v^2/r^2 But I=2/5 mr^2 so TE/Re= (1/2 mv^2)/(Mr^2*v^2/5)=2.5 check
March 13, 2017

Physics
from 15mi/hr to /???????
March 12, 2017

English
This practice could help to find cures for the illnesses as well as animals. >> Makes no sense. What illnesses? How is it good for the animals? were they sick?
March 12, 2017

math
Have you studied the Least Integer Function (sometimes called a step function)? https://www.khanacademy.org/math/algebra/algebra-functions/piecewise-functions/e/evaluate-step-functions-from-their-graph
March 11, 2017

Math
L=W+16 P=2L+2w=2(W+16)+2W=4W+32 4W=200-32 W=168/4=42 L=58
March 11, 2017

math
what is 7*5? Think about that. That is the smallest whole number. But the smallest number you can multiply A and get a perfect square is = 1/(5^3*7^3*3^2) multiplying it then will leave you with A'=9, a perfect square. i am not certain your teacher was thinking of that, ...
March 11, 2017

Science
depends on what you mean by chemical and biological. Some hold that biological is inherently chemical.. and, depends on what you mean by great thrust: Much effort is aiming for breakthrus in the biological area, especially in genetic engineering. But honestly, those are just ...
March 11, 2017

Science
power=I^2*R dp=2IR*dI dp=2di * RI so the increment in dp is 2Percent
March 11, 2017

physics
one wonders where the charges are.
March 10, 2017

physics
What is coulomb's law? Do you have a question on it?
March 10, 2017

PRe calc story problem!!
story problem? Calculus is not elementary school. Q(t)=Qo*ekt 25=100*e12k ln of both sides... ln(1/4)=12k -1.38629436=k*12 solve for k then, for half life... .5=ek*t solve for t (take ln of both sides) thalf=ln(.5)/k
March 10, 2017

Electricity and Magnetism
Tangental accelertation? the magnet field put a force on the electron perpendicular to the electron path. So If I am understanding the question correctly, the tangential acceleration is zero, as the tangential velocity is not changing.
March 10, 2017

Science
bp was elevated?
March 10, 2017

Social Studies
D. The Muslim nations had traded with the far East for centuries, and those goods became commonplace in Europe. AFter the muslims were driven off, the desire for those goods remained
March 9, 2017

physics
I will be happy to critique your thinking or work on this.
March 9, 2017

physics
Use conservation of momentum to solve this.
March 9, 2017

English
c and e
March 9, 2017

physics
Look up the moment of inertia for a disk, and the sphere. flywheel(disk)=Ifly*w sphere=Isphere*ws set them equal, solve for ws put radii in meters...
March 8, 2017

physics
momentum is conserved initial momentum=finalmomentum 2/5 *M*6.96E8wi=2/3*M*6.37E6*wf wi=1rev/25days wf=wi*(6.96E8/6.37E6) = about 4 revs/day or 27.46rad/day
March 8, 2017

Algebra
It is prime, cannot be factored in the real number system
March 8, 2017

science
the hydrogen attached to the -O- in the OH is the detachable H
March 8, 2017

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