Thursday
April 28, 2016

Posts by bobpursley

Total # Posts: 40,640

Math
what is 5/10
April 28, 2016

Math
2pennies.two nickels. on 50cent piece.
April 28, 2016

Math
what is 1/3 of 40?
April 28, 2016

Physics
mass=1.2E5*12.5/(69)^2 recheck that.
April 28, 2016

Physics
Sum of the heats gained is zero in the cup. Heatgained by water+heatgained by zinc=0 50cw*(28.1-27)+11.98Czinc*(28.1-78.4)=0 solve for Czinc
April 28, 2016

Science
http://www.physicsclassroom.com/class/refrn/Lesson-2/The-Angle-of-Refraction
April 28, 2016

MATHS
find the volume of the outside radius, then subtract the inside volume. Volume metal=Length*PI(13^2-10^2) length = 300cm
April 28, 2016

Science
You can do a reaction with sodium hydroxide which will proceed only if the pH is very high, proving sodium hydroxide is a high pH base. This is how: Al2O3 + 2 NaOH --> 2Na+ + 2[Al(OH)4]- The species, [Al(OH)4]- is the tetrahydroxoaluminate complex ion. It only appears at ...
April 28, 2016

Physics
time between shots: 1/10 sec distance=300m/s*.1s=30m
April 28, 2016

Chemistry
figure moles of KClO3, then three halves times that. MolesKClO3=125g/122.5 moles O=3*125/122.5 molesO2= 3/2 * 125/122.5
April 28, 2016

Physics help Rolling Motion!!
total energy at bottom=increase in PE 1/2 mv^2+1/2 I V^2/r^2=mg*2.2sin30 solve for I.
April 28, 2016

Science
time=timeperframe*frames =1/240*18=3/80 sec velocity=distance/time=.45m/timeabove
April 28, 2016

university of phri
a=change velocity/time=(vf-vi)/2 vi=12 consider position: sf=si+at -5=3+a*2 or a=-4cm/s^2
April 28, 2016

Physics help
50db? dbincrease=10logPower 50=10*logP p=10^5 Rembember, 3 db is doubling power. so you have doubled power almost 17 times.. Put this in your google search window: 2^17=
April 28, 2016

Physics.. Force and pressure
pressure=weight/area = 24m^3*800kg/m^3*9.8N/kg *1/12m^2 = 2*800*9.8 Pascals
April 28, 2016

math
B=1/3 * 390=130 records S=.5*(390-130)=.5(260)=130 R=(390-130-130=130
April 27, 2016

trigonometry
theta=5/9?
April 27, 2016

algebra
Dolls=3w+254
April 27, 2016

chemistry
find moles of S. molesS=totalmass*.10263/32=.39/32= .0122 molesO=4*.0122=.0488 massO=.0488*16=.788 grams massX=(3.9-.788-.39)=2.72 molesX=2*.0122=.0244 molemassX=mass/moles=2.72/.0244=111.5 check that, most of it was in my head.
April 27, 2016

Science
yes
April 27, 2016

physics
The ball is the same size, regardless of where she is standing, or sitting.
April 27, 2016

Physics
at the top: mv^2/r=mg v^2=rg KE at top: 1/2 m v^2=1/2 m rg PE at top mag(2r) KE at bottome+1/2 m rg+mg(2r) 1/2 mvb^2=1/2 mrg+2rmg vb^2=5rg veloecitybaottom=sqrt(5rg
April 27, 2016

math
600=(2x+20)(x+10) 600=2x^2 +40x+200 x^2+20x-500=0 x=(-20+-sqrt(400+2000) )/2 x= -10 +-sqrt(600) x=sqrt(600) -10
April 26, 2016

PHYSICS ROLLING MOTION!!!
rev=distance/PI*D= 2000*100cm/2PI*44=1445.8revs
April 26, 2016

AP Physics
1/2 m vf^2+328*distance=work done but distance=avgspeed*time=12/2*12.2 so calculate work done. Now divide by time, and you have power.
April 26, 2016

PHYSICS HELP DENSITY
assume Mass M for the object. in water, 24=M-densitywater*volume in oil, 48=M- densityoil*volume subtract top equation from bottom. 24=densitywater*volume-densitoil*volume volume=24/(1-.8) cm^3 volume= 120cm^3 Now, solve for M. 24=M-1*120 M=144grams density=144/120 g/cm^3
April 26, 2016

Chemistry
2C+2SO2>> CS2 + CO2 Well, for each mole of SO2, you get one-half mole of CO2 MolesCO2=1/2 * 8/molmassSO2
April 26, 2016

Chemistry
CH3COOH>> H+ + CH3COO- k=(h+)(CH3COOH-)/.83 k=2H/.83 solve for H I get about 1.7E-5*.83/2=.70E-5 about the pH=-logH=about 5.1 Use your table for Ka, and you calculator to check, this is estimated.
April 26, 2016

chemistry
and?
April 26, 2016

chemistry
convert the photon wavelenght to energy, in ev. subtract the 7.5eV, and you have it. E=PlancksConstant*speedlight/lambda h=4.15)×10−15 eV s
April 26, 2016

Chemistry
the sum of the heats gained is zero. qH2O+qFe=0 25*4.184(Tf-398K)+24*.449*(Tf-298)=0 now solve for Tf in that.
April 25, 2016

Chemistry
Of course. V=nRT/P density=mass/volume=mass*P/nRT if you double temp, density goes to 1/2.
April 25, 2016

science
intermolecular Hydrogen bonding in the water.
April 25, 2016

History
the impact of the spanish american war was to reduce splintering in the democratic party in SC Unions were formed to increase pay for workers. Tillman believed the conservatives were mainly white supremacist.
April 25, 2016

Chemistry
molarity=mass/(molmass*volumeinliters) One liter: is that absolutely precise? It is not 1.00000000 liter. Ok, ignoring the volume precision, the mass is five sig digits, mass is four, so I would take it to four sig digits, but honestly, one liter...in the real world one would ...
April 25, 2016

mathematics
You have two sides and the included angle, use law of cosines. I think the angle is 70 deg, check it.
April 25, 2016

Physics
find his KE as he grabs on. Now convert that to PE. mgh=1/2 mv^2 solve for h. angle: draw the figure. arccos=(1.50-height)/1.5
April 25, 2016

science 6th grade
correct
April 25, 2016

Science
velocity? is it moving? float? is its density less than water?
April 25, 2016

chemistry
Ooops, that is .035 in the denominator
April 25, 2016

chemistry
determine the heat released from the solution mass. heat=(.1+.1)*cwater*(39.7-35) Now look a the reaction: 3Ca(OH)2+2H3PO4>>Ca3(PO4)2+6H2O Now looking at the reactants, you started with .03moles Ca(OH)2, and .07 mles H3PO4. So you have excess Ca(OH)2. The phopsporic acid...
April 25, 2016

Science
Well, heat the ice and melt it first. Heat1=10*cice*(0+20)+10Hf now it is at zero C then find the heat released by the steam to get to 100C Heat2=50*Csteam(100-120)+50Hv notice this is negative heat gained.(Hv is negative). Now, you have water at 100C and OC. Sum of heats is ...
April 25, 2016

English
1 and 2 infer she was garbage and he got rid of her, in my opinion. The first sentence is trash talk. "Broke up" is understand a relationship was "broken" and couldn't be fixed, like a glass dish. Other words: "ended the relationship with his"...
April 25, 2016

Science
Yep, my guess was right. You have to start with the same temp so you can measure the heat rise in each with final temperature.
April 24, 2016

Science
I bet you are measuring temperature rise (due to thermal capacity). It is important because you are measuring temperatur increase, I think.
April 24, 2016

Science
In some instances, it is important that they do not start at the same temperature. I wonder what the teacher has in mind here, unless you are measuring a rate of reaction, and temperature is a factor.
April 24, 2016

Chemistry
total moles=30moles PV=nRT solve for P, change temps to K b.Aren't these the same question?
April 24, 2016

Chemistry
wouldn't it be 3/2 the rate for of the dissapearance of Ozone? The coefficents tell us that.
April 24, 2016

linear modeling
Rain=rate*time rain= .25in/hr * time
April 24, 2016

Absolute and relative change
Math101=1.2*Math123 Math123=math101 / 1.2
April 24, 2016

Absolute and relative change
advertised price(1.24)=279 solve for advertised price
April 24, 2016

Math please help
scale: x axis 000 .001 .002 .003 .004 .005....
April 24, 2016

Math please help
I think I would go in thousandths, start at zero, go to .009, in increments of one-thousandths. the last two estimate the last digit position
April 24, 2016

math
tanTheta=5/8 theta= arcTan(5/8)
April 24, 2016

life orientation
We will be happy to check your work.
April 24, 2016

geometry
volume=4/3* PI r^3 but area=4PIr^2 so r^2=9PI/4Pi=9/4 or r= 3/2 volume=4/3 * PI* (3/2)^3
April 24, 2016

Calculus
y=mx+b y=-x+b 5=-2+b b=7
April 24, 2016

Calculus
Correct
April 24, 2016

Analytical Chemistry
And I wonder what the Lab was?
April 24, 2016

Chemistry
6H2O+ 9SO2 >>>6H2S + 3SO3 + 5 O3
April 24, 2016

Chemistry
well, you get 2 moles of gas for each mole of P4. moles P4=23.42g/4*30.97=.189moles Moles gas=2*.189 PV=nRT P=nRT/V= solve for P.
April 24, 2016

statistics
Pr(all are good)=.96^6 Pr(six bad)=.04^6 Pr(five+good)=.04 *.96^5 + .96^6 Pr(two or more defiective)=Pr(all good or one defective)=.96^6+.96*.04^5
April 24, 2016

math
30 people*2cups/people*1quart/4cups*1gal/4qts= 30*2/16=60/16 gallons
April 24, 2016

Texas History
"Improve" is a loaded word. The big changes during WWII were industrialization along the coast, with petrochemical industries, and the aircraft manufacturing facilities in the N Texas area, and the great move of population form rural to cities during the war.
April 24, 2016

Science
This is a vector add problem. Take the corners (same force, 90 degrees apart), and the diagonal force (1/2 of teach of the other forces (think out why)), and add them as vectors.
April 24, 2016

Physics
voltages will be equal. q=C V charge on first: 2E-6&50 charge on second: 4E-6*100 so the charges total is (added)5E-6*100 so in the final condiguration, qt=sum of charges above=5E-6*100 and the voltages are equal. total capacitance in parallel is 6E-6, so V=q/C=5E-6*100/6E-6 =...
April 24, 2016

Physics
a. 1500v b. q=C/V=120E-12/500 C c. add the energies of each 1/2 q^2/V for each of the three, V=500, q=above
April 24, 2016

Physics
KE after: 1/2 1.5(1.65^2)+1/2*3.5*(1.65^2)=13.6/2 Not your resulet.
April 23, 2016

Calculas
cost=5x^2+5*3x^2
April 23, 2016

Calculus
f(2.5)=f(2)+f'(2)*.5
April 23, 2016

math
x^2 +6x+9 + 5 (x+3)^2 + 5
April 23, 2016

Logarithm
(4^2)2 or 4^4=256 log4(256)=4 log2 (1/64)=log2(1/8)^2=2*(-3)=-6
April 23, 2016

Physicis
change temps to Kelvins. combined gas law: p1V1T2=P2V2T1
April 23, 2016

Chemistry
It must be 1.5x that of ozone rate.
April 22, 2016

Calculus I
y^2=-x^2+2x y^2 -1 =-(x^2-2x+1) Y^2+(x-1)^2=1 Isn't that a circle of radius 1, centered at 1,0?
April 22, 2016

Science
protons+neutrons=53 neutrons=53-26
April 22, 2016

Physics
KE=1/2 m v^2 v= sqrt(2KE/m)=sqrt(2*3.82/.294)=5.10 m/s distance=velocity*time=5.1(time) time=sqrt(2*.96/9.81)=.442sec h=5.1*.442 meters
April 22, 2016

Chemistry
You have increased order, making three volumes two. Entropy decreases
April 22, 2016

Math
2,7,8,11 are wrong
April 22, 2016

physics
5 seconds. The pitch may cnage, but the duration does not.
April 22, 2016

Physics
well, one wants to change the moment of inertia to half. Flat cylinder? should be more like a disk, to me. Initial I=1/2 900* r^2 final I= 2x of that initial final I= 1/2 900*r^2+500c^2 where c is the radius of the child from center. 900*r^2=1/2 900*r^2+500c^2 450 r^2=500c^2 ...
April 22, 2016

Chemistry
sqrt(2.4E-14)= 1.55E-7 which is the (H3O+) concentration pH=-log above=6.84
April 20, 2016

MATH
expected=1/2 * 1/2=1/4 expected number = 60/4=30 so it occured...
April 20, 2016

Math
.86=e^-k k=-ln.86 .78=e^-kt t= -ln.78 /k= ln.78 / ln.88
April 20, 2016

Math
solve? there is no equal sign!
April 20, 2016

Physics
time to fall: h=1/2 g t^2 t=sqrt(2*22.9/9.8) horizontal v=d/t=6.2/t
April 20, 2016

Maths
volume wood=volume outside-volume inside = (10+2*5)(8+2*5)(11+2*5)-10*8*11 = 20*18*21-10*8*11 Man, that is thick wood.
April 20, 2016

Functions
Tan x cannot have an amplitude, as tan 90 deg goes to infinity. use sin or cosine functions.
April 20, 2016

electricity
90 ohms.
April 20, 2016

Physics
emf=IRt=1.5(28) volts terminal voltage=above-1.5*3 waster power: 1.5^2*3 percent=wasted power/EMF*1.5
April 20, 2016

Physics
depends on how the batteries are connected, series or parallel. Assuming series: power=I^2(50) where I= (2*1.8 )/51.2
April 20, 2016

math log rules / chem
Your first line E2-E1. You dropped a negative sign on the first term. -log(F+S)+logF log (F/(F+S))
April 20, 2016

Physics
change weight of car to kg, by dividing by g. 588.6E3/g * 1km/hr=(588.6E3/g+392.40)V solve for V.
April 20, 2016

physics
same mass, same velocity opposite direction? Joint velocity=zero
April 20, 2016

Chemistry
They both contain 1M of ions.
April 19, 2016

physics
and the question is....
April 19, 2016

physics
and the qeustion is...
April 19, 2016

Physics
E=q/r^2 r=sqrt(q/E)
April 19, 2016

Physics
did you add the forces as vectors?
April 18, 2016

math
(x^2-1)(x-1) x^3-x^2-x+1
April 18, 2016

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