Thursday

April 28, 2016
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*

**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*