Monday

September 1, 2014

September 1, 2014

Total # Posts: 18,150

**Physics**

slope of vector A = -6.5/5 so slope of perpendicular = 5/6.5 or C dot A = 0 5 Cx - 6.5 Cy = 0 Cy/Cx = 5/6.5 if Cx = 6.5 k then Cy = 5 k C dot B = 6.5 k (-2.5) + 5 k (7) = 15 so -16.25 k + 35 k = 15 18.75 k = 15 k = .8 so Cx = .8 * 6.5 Cy = .8 * 5
*August 30, 2014*

**History**

By the way, Maine was part of Massachusetts and Vermont was either New Hampshire or New York depending on who you asked :)
*August 29, 2014*

**science**

1-.2 = .8 1-.6 = .4 .8 * .4 * 50
*August 28, 2014*

**math**

No matter how you turn it, you two are right and person z is wrong :)
*August 28, 2014*

**History**

Making it worse is that often the same crop is grown in the same field season after season, making it super easy for the bugs.
*August 28, 2014*

**History**

Those crops tend to be produced as mono cultures, mile after mile of fields of the same crop. That makes it easy for the insects to adapt to the crop culture and multiply fast without having to look around for the stuff they like. It is sort of like you are growing hordes of ...
*August 28, 2014*

**Chem Help**

whatever you are distilling boils at a lower temp
*August 28, 2014*

**algebra**

t s^2 = (R-3) s^2 = (R-3)/t s = plus or minus sqrt [(R-3)/t ]
*August 28, 2014*

**algebra**

multiply everything by 10 2 x - 5 x = 210 -3 x = 210 x = -210/3 x = -70
*August 28, 2014*

**algebra**

5/3 and sqrt 3 :)
*August 28, 2014*

**Geography**

Alaska only in the winter :) There are a lot of glaciers in Alaska but I would not say it is mainly covered in ice all year.
*August 28, 2014*

**algebra 2**

what about 1.573 ?
*August 28, 2014*

**Math Problem (please help)**

revenue = 4.59 n cost = 4000 + 2.19 n to break even: 4.59 n = 4000 + 2.19 n profit = revenue - cost 5500 = 4.59 n - 4000 - 2.19 n
*August 28, 2014*

**sorry, forgot 10, you are right**

10/k = 4.67 * 10^4
*August 28, 2014*

**Physics ...**

number produced per second = 10 number lost per second = r = k n so dn/dt = 10 - k n max when dn/dt = 0 or when n = 10/k now find k from half life experiment dn/dt = -k n dn/n = -k dt ln n = -k t + c n = Ni e^-kt when t = 3.24 * 10^3 n/Ni = .5 ln .5 = -k (3.24*10^3) -.693 = -k...
*August 28, 2014*

**science**

work = force * distance in direction of force 2.7 = 4.5 x
*August 28, 2014*

**Physics**

100 west and 100 east
*August 28, 2014*

**Physics**

20 * 200 zero again, but you know that :)
*August 28, 2014*

**Physics**

They look right to me. Of course she is not really moving it for the half of the trip that is down so you could make an argument that she is really only moving it up 450 cm and it is moving itself down 450 cm. It is the words "release" and "drop" that cause...
*August 28, 2014*

**science**

Force = charge * electric field or F = Q E if you do F = m a you can use the mass but you can use work done = change in Ke work done = change in Ke= force * distance so Q E d = Ke 2 meters= 3.25*10^-15/(1.602^10^-19 E)
*August 28, 2014*

**math problem solving**

I am assuming you mean 35,252 = 30,000 + 5,000 + 200 + 50 + 2
*August 28, 2014*

**math problem solving**

5000 50
*August 28, 2014*

**Physical sciences**

H2SO4 + 2NaOH ---> 2 H2O + Na2SO4
*August 28, 2014*

**physics**

Unless the person takes care to place the load over the original CG. People who carry burdens on their heads have great posture :)
*August 28, 2014*

**Intro Physics Help**

east 20 then west 30 then east 40 total run = 20 + 30 + 40 use for a total east = 20 - 30 + 40 use for b
*August 28, 2014*

**Science in motion pHY 102**

if both the 30 Newtons and the 20 Newtons act in the same direction then 30 N + 20 N = 50 N
*August 28, 2014*

**Math**

I think there are twice as many pairs of corresponding angles as interior because exterior also correspond. Yes of it is a parallelogram (including a rectangle). No is sides are all different lengths or for example a trapezoid. Right right
*August 28, 2014*

**math**

(7/4) * 5 = 35/4
*August 28, 2014*

**Math**

probability that he will not hit on a given shot = 3/4 probability that he will miss 4 times in a row = (3/4)^4 = 81/256 so probability that he will hit = 1 - 81/256 = 175/256 or about .684
*August 28, 2014*

**Idk..**

voter pour moi svp means vote for me please svp is abbreviation for: s'il vous plaît "if you please" I do not know what " puex to " means
*August 28, 2014*

**Math**

Huh? The three questions are all the same. Of course they all have the same answer. 0 = 4 x - 28 x = 28/4 x = 7
*August 28, 2014*

**Math**

y = k / x^3 .5 = k / 8 k = 4 y = 4 / x^3
*August 28, 2014*

**Th**

A = k a p side s = p/n base of triangle of one section = s = p/n 1/2 base = p/2n if n sides then area = n (a) p/2n) = a p/2
*August 28, 2014*

**Math**

Rational is a ratio of integers, a fraction. see: http://www.mathsisfun.com/definitions/rational-number.html
*August 28, 2014*

**algebra**

1. ok 2. ok 3> !!!! (6,3) NO agree (4,0) YES agree (3,-1) YES DISAGREE 3 - 4 = -1 yes (2,-4) NO DISAGREE 2 - 4 = -2 not -4
*August 28, 2014*

**AP Calc. AB**

d/dx (1/8) x^3 = (1/8) d/dx x^3 = (1/8) (3 x^2) = (3/8) x^2 when x = 4 = (3/8)(16) = 6
*August 27, 2014*

**physics**

a = F/m = - 50/20 = -2.5 v = Vi + a t 0 = 15 - 2.5 t t = 15/2.5
*August 27, 2014*

**Maths**

2875,35 - 2010,50
*August 27, 2014*

**Algebra**

I suppose that is true. Open y = 7 - 3 Closed 4 = 7 - 3
*August 27, 2014*

**Science**

A leg, by any other name, is still a leg.
*August 27, 2014*

**physics**

take 40 away from 200
*August 27, 2014*

**algeba**

Then multiply by P Q so far BP (not the oil spill company) + BQ = PQ B (P+Q) = PQ one more step and you are home
*August 27, 2014*

**algeba**

multiply everything both sides by B
*August 27, 2014*

**Math**

Sin A/a = sin B/b = sin C/c
*August 27, 2014*

**maths**

120
*August 27, 2014*

**Physics**

I can say noting about velocity because all I have is speed. For velocity direction is also required. For speed you can use a speedometer. For velocity you need both a speedometer and a compass.
*August 27, 2014*

**algebra**

21/7 + 3(36) 3 + 108 111
*August 26, 2014*

**Algebra**

LOL , eight crackers per serving * 12 servings = 96 indeed
*August 26, 2014*

**physics**

Sorry, I made that too hard. the two unknown vectors result in a vector that is equal and opposite to the first one so B + C is 136 units 35 deg south of east |B|^2 + |C|^2 = 136 ^2 Bx + Cx = 136 cos 35 By + Cy = -136 sin 35 Bx = |B| sin 69 By = |B| cos 69 Cx = -|C| sin 19 Cy...
*August 26, 2014*

**physics**

add up the north components (y axis) add up the east components (x axis) take the square root of the sum of the squares for the magnitude Tan theta = total y/total x but that theta is the math theta, counterclockwise from x axis for compass angle -- > 90 - theta
*August 26, 2014*

**math**

LOL, more MITx ?
*August 26, 2014*

**math**

distributive property (3x-2)(4x-3y) if you find that easier
*August 26, 2014*

**math**

remember (a^2 - b^2 ) = (a-b)(a+b)
*August 26, 2014*

**math**

(.2*12.5 -.02*12.5)/(.05 *.2) (.2*12.5 - .2*1.25 ) / (.05*.2) (12.5 - 1.25) / .05 1125 /5 225
*August 26, 2014*

**Geometry**

You are welcome :)
*August 26, 2014*

**Geometry**

I drew a diagram which I can not reproduce here A--------------------------------C --------------------B on top line A ---------------D ------16------C A ---------------D --------------------H A-------E --------D A ------E ---F ---D A-------E -G-F
*August 26, 2014*

**Geometry**

First find AG AD = 16 AE = 8 and EF = 4 so EG = 2 AE + EG = AG = 8 + 2 = 10 Now find AH AD = 16 AB = 64 so DB =64 - 16 = 48 half of that is 24 so AH = 16+24 = 40 GH = AH-AG = 40 - 10 = 30
*August 26, 2014*

**Math**

155.09 + 5.77
*August 26, 2014*

**math**

sketch it first angle from x axis = tan^-1 (8/6) = 53.1 deg so first clockwise 60 degrees so -6.87 degrees (in quadrant 4) tan -6.67 = -.12 so if x = 1, y = -.12 now we want that to be a unit vector so find magnitude of what we have r = sqrt(x^2 + y^2) = sqrt 1.014 = 1.007 so...
*August 26, 2014*

**Calculus**

Hi = 500 Vi = +14 v = Vi - 9.8 t v = 14 - 9.8 t at top, v = 0 so at top t = 14/9.8 h = Hi + Vi t - (9.8/2) t^2 so for example max height is h = 500+14 (14/9.8)-(9.8/2)(14^2)/9.8^2 or h = 500 + (1/2)(14^2)/9.8 at top
*August 26, 2014*

**physics**

it is precise it is NOT accurate 455 is NOT 500
*August 26, 2014*

**physics**

precise but not very accurate (i think its this one) yes, values close together but wrong
*August 26, 2014*

**physics**

We can not see your list. I would say wrong :)
*August 26, 2014*

**Physics**

v = Vinitial + a t if a is constant so of course no acceleration = change in velocity /change in time
*August 26, 2014*

**compound interest**

200 *1.2^3 + 200*1.2^2 + 200*1.2
*August 26, 2014*

**Science**

well, I would pick a) if length were spelled correctly. Farenheit is not SI weight is force, gram is mass meniscus is shape of the surface in a barometer or thermometer
*August 26, 2014*

**math**

I can not write TODAY because it was Yesterday :(
*August 26, 2014*

**Physics**

That depends what direction you define as positive. If + is direction from your house out, then a is positive leaving and negative as you decelerate (brake) to land at your destination. However as you start home, if you do not redefine the positive direction, your increase in ...
*August 26, 2014*

**Physics**

You are welcome.
*August 26, 2014*

**Physics**

The acceleration remains constant one g down as the speed up drops to zero at the top of the flight and then it starts downward hitting the ground at the same speed down it started up but the opposite direction.
*August 26, 2014*

**physics**

F = m a = 18 * 3 N
*August 26, 2014*

**Physics MITx? ME course 2 ?**

Looks like a course 2 MITx problem to me. You are on your own.
*August 26, 2014*

**Math**

You just did.
*August 26, 2014*

**geometry**

Draw a good sketch and make the incident and reflected rays at the same angle to the perpendicular to the mirror at the bottom.
*August 26, 2014*

**chemistry**

C6H6 --> 6*12 + 6 = 78 grams/mol so we have 1/78 mol 1/78 mol in 0.1 liter --> 10/78 molarity etc
*August 26, 2014*

**Physics - figure with angles?**

If you tried to copy and paste it, that does not work here.
*August 25, 2014*

**Math**

green on first try = 1/4 green on second try: red first = 3/4 then green = 1/3 so 3/4 * 1/3 = 1/4 green on third try red first = 3/4 red second = 2/3 green third = 1/2 3/4 * 2/3 * 1/2 = 1/4 green o fourth try red first = 3/4 red second = 2/3 red third = 1/2 green fourth = 1/1 ...
*August 25, 2014*

**Calculus-Math**

well, we know we keep the 4 :) Let z = 4(sec u)^7 and u = pi t - 6 then dz/du = 4 * 7 (sec u)^6 d sec u/du = 28 (sec u)^6 (sec u )(tan u) = 28 sec^7 u tan u dz/dt = dz/du * du/dt = dz/du * pi so dz/dt = 28 pi sec^7(pi t-6)tan(pi t-6)
*August 25, 2014*

**French**

Pourriez-vous traduire ces expressions pour moi ?
*August 25, 2014*

**9th Grade Bio**

In "respiration" by the way you are basically oxidizing organic molecules using O2 from the air, sort of like burning wood to produce energy and CO2 but at much lower temperature :) At least that is the way a physicist as opposed to a biologist sees it.
*August 25, 2014*

**9th Grade Bio**

You are welcome.
*August 25, 2014*

**9th Grade Bio**

https://www.google.com/search?q=respiration+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb
*August 25, 2014*

**Math**

y = (4/3) x - 6 3 x = 7 - (4/3)x + 6 9 x = 21 - 4 x + 18 13 x = 39 x = 3 then y = (4/3)(3) - 6 y = -2
*August 25, 2014*

**Algebra**

No, when you list ordered pair as (a,b) a is independent variable x and b is dependent variable y
*August 25, 2014*

**Algebra**

try using 0 for x and 3 for y 3 = 0 + 3 sure enough
*August 25, 2014*

**math**

10^3 * 10^3 = 10^6 = one million
*August 25, 2014*

**Algebra**

2 x^2 = 108 x^2 = 54 note: 54 = 6 * 9 = 6 * 3^2 so x = 3 sqrt 6 or x = -3 sqrt 6
*August 25, 2014*

**chem**

the gas is still about 80% N2 so 8 atm It would also be 2 atm O2 instead of 0.20 atm O2 or ten times the O2 pressure. Both the high partial pressure of N2 and of O2 cause problems for divers and for deep diving for extended times mixtures with lower O2 content and Helium ...
*August 25, 2014*

**algebra**

draw a number line put a dot at +7 go left negative one when you go left negative, you go right
*August 25, 2014*

**math**

four choices for the first three for the second two for the third one for the fourth 4*3*2*1 = 24 usually this is called permutations and is written as n! where n! = n * (n-1) * (n-2) ....*1
*August 25, 2014*

**Agebra**

you did
*August 25, 2014*

**Physical Science**

LOL You only have two significant figures in 3.0 365.25 * 3.0 = 1095.75 which to two sig figs is 11*10^2
*August 25, 2014*

**Physical Science**

100 * .2/37 100 * .3/37
*August 25, 2014*

**geography**

because it is big and you only see a tiny bit of the surface of the sphere because you are so close to the surface like an ant on a huge round balloon. If you get far away, like in an orbiting space station, you can see the curvature.
*August 25, 2014*

**business math**

markup = 25,869.57 - 11,900 = 13,969.57 13,969.57 * 100 / 25,869.57 = 54
*August 25, 2014*

**phychics**

Moreover for the sake of us physicists, please spell physics.
*August 25, 2014*

**phychics - typos**

what is the friction on this friction track you gave the speed at the top - why do you ask for it? If it is another hill, what is the height?
*August 25, 2014*

**Physical Science**

I do not know because I do not know the true value. However I can give the percentage range from the average of the two. (37.2+36.7)/2 = 36.95 difference = +/- 0.25 100* .25/36.95 = + or - .68%
*August 25, 2014*

**Ed Tech**

I have a sneaking suspicion that they want antivirus software if they are downloading stuff.
*August 25, 2014*

**Math**

The round one with red and blue and white stripes
*August 25, 2014*

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