Friday

March 6, 2015

March 6, 2015

Total # Posts: 20,652

**math**

.9 x = 36 x = 36/.9 = 40
*September 12, 2014*

**physics**

average velocity = -617/105 = -5.88 m/s and average speed = 5.88 m/s ================================ in anticipation of a part B: x = Xi + Vi t + (1/2) a t^2 -617 = 0 + 0 t + (1/2)a (105)^2 a = -1234/105^2 a = - .112 m/s^2
*September 12, 2014*

**Physics help please!**

I assume you are talking about a nuclear reaction. In that case some mass is released as energy by the relationship E = m c^2
*September 12, 2014*

**Algebra**

yes, or complete the square -(1/2) x^2 + 20 x = A - 800 x^2 - 40 x = -2 A + 1600 x^2-40x+20^2 = - 2A + 2000 = -2(A-1000) (x - 20)^2 = -2 (A-1000) vertex at x = 20, A = 1000
*September 12, 2014*

**Math, Physics**

distance = rate * time d = 1.9 *initial speed * cos 46 now vertical problem Vi = initial speed * sin 46 v = Vi - 9.8 t at top 0 = Vi - 9.8* (1.9/2) time up is half total time so Vi = [ 4.9 * 1.9 ] so initial speed = [ 4.9 * 1.9 ]/sin 46 then go back to d = 1.9 *initial speed...
*September 11, 2014*

**Physics repeated question**

been there, done that.
*September 11, 2014*

**Physics**

v = Vi - 9.81 t 0 = 1.23 - 9.81 t solve for t then double it if you want to come back down.
*September 11, 2014*

**Math**

top line (1 + 2) + (3 + 4) = 10 = (1+3) + (2 + 4) = 10 associate property of addition d. as for the rest c. add y values 2+4 = 6 now 1 + 6 + 3+6 = 16 NO e. sum of x values + sum of complex conjugates of y values?
*September 11, 2014*

**algebra 1**

rod d = v * 5 hours Marsha d = (v+42) * 2 hours so 5 v = 2 v + 84
*September 11, 2014*

**Maths**

sin theta = 2.1/3.8 = opposite/hypotenuse ================================ same thing sin theta = 0.75/5.4
*September 11, 2014*

**math**

4 x^2 - 4 x + 5 = 0 x = [ 4 +/- sqrt (16 -80) ]/8 = 1/2 +/- (1/8)sqrt (-64) = 1/2 +/- i
*September 11, 2014*

**maths b**

http://davidmlane.com/hyperstat/z_table.html
*September 11, 2014*

**maths a**

http://davidmlane.com/hyperstat/z_table.html careful about parentheses z= (x-u)/SD = (34.5 -46.5) /8.7 = - 1.38
*September 11, 2014*

**maths a**

English z = (68-52)/10 = 1.6 SDs above average Math z = (68 - 55)/8 = 1.625 SDs above average, better
*September 11, 2014*

**2**

a = 6500/60 then divide by 9.8
*September 11, 2014*

**2**

forget speed of light in this context, so much faster than sound that basically it is infinite. All that matters is the creeping speed of sound. 6.5 s * speed of sound in air = distance then divide that distance by 3*10^8
*September 11, 2014*

**1**

6.5 * 343 (Ignore speed of light)
*September 11, 2014*

**phusics**

x = Xi + Vi t + .5 a t^2 10 = 20 t - 5 t^2 solve for t or just use average speed up = 5 m/s so time = distance/speed = 10/5 = 5
*September 11, 2014*

**Science**

work done = change in Ke (1/2) (.5)(v^2) = 810 * 4 * 10^-3
*September 10, 2014*

**Physics**

980 * .25 Newtons
*September 10, 2014*

**Physics**

a = 3 m/s^2 Vi = 0 d = 24 m d = (1/2) a t^2 24 = (1/2)(3)t^2 t^2 = 48/3 = 16 t = 4 seconds v = Vi + a t v = 0 + 3 (4) v = 12 m/s
*September 10, 2014*

**math**

(1/3)Jill + 10 = 55 Jill / 3 = 45 Jill = 3 * 45
*September 10, 2014*

**Algebra 2**

x = [ -10 +/- sqrt (100 + 80) ]/2 x = -5 +/- .5 sqrt(180) x = -5 +/- .5 sqrt ( 9 * 4 * 5) x = -5 +/- 3 sqrt 5
*September 9, 2014*

**science**

200 meters in 5 seconds average speed = 200/5 = 40 m/s so speed is 80 m/s at 200 m it slows down after that so 80 is your answer goes at 80 for 300 m time = 300/80 = 30/8 = 15/4 seconds between 200 and 500 now from 500 m and 80 m/s, brakes down to zero at -2 m/s^2 0 = 80 - 2 t...
*September 9, 2014*

**8th grade math**

147 * 5/3 = 216 * 5/3 = (note, everything is nicely divisible by 3) then subtract
*September 9, 2014*

**Grade**

average of four scores = sum of 4 scores / 4 = 340/4
*September 9, 2014*

**Alegbra**

what if it were x^2 - 2 x - 3 ?? (x-3)(x+1) now try
*September 9, 2014*

**8th**

120 min total weight time = 120 - 21 - 45 then 100 (weight time) / 120
*September 9, 2014*

**Chm Help Please!!!**

I assume that 205 C boiling point is at atmospheric pressure. If you reduce the pressure with a vacuum pump maybe you can get the stuff to boil at lower than 150 degrees. That also cuts down on the reaction with air if there is little present :)
*September 9, 2014*

**math**

done
*September 9, 2014*

**math**

They are the same.
*September 9, 2014*

**Math Problem (please help)**

since e^ln x = x e^ln e = e^1 = e
*September 9, 2014*

**Math 6th grade**

11 is just the first one :) There are lots.
*September 9, 2014*

**Math 6th grade**

divide by five, remainder 1 6, 11, 16, 21, 26, 31 , ....... divide by 4, remainder 3 7 , 11 , 15 , 19 , 23 , 27 , 31 score ! 31 makes 7 rows of 4 with 3 left over 31 makes 6 rows of 5 with 1 let over
*September 9, 2014*

**Math Problem (please help)**

You are welcome :)
*September 9, 2014*

**Math Problem (please help)**

e^rt = e^(.03*30) = e^.9 = 2.4596 times 30,000 = $ 73,788.09
*September 9, 2014*

**PRECALCULUS**

2 x + 2 y = P y = 18/x 2x + 36/x = P
*September 9, 2014*

**physics**

Has unknown speed Vi at h = .18 m while coasting upward: 0 = Vi - 9.8 t so t = Vi/9.8 2.3 = .18 + Vi t - (1/2) 9.8 t^2 2.12 = Vi^2/9.8 - (1/2) Vi^2/9.8 (1/2) Vi^2 = 9.8*2.12 Vi = 6.45 m/s at .18 meters so average speed between ground and .18 meters = 6.45/2 = 3.22 m/s so time ...
*September 9, 2014*

**Math...Help.Thx**

P = k T 90 = k (60) k = 9/6 = 1.5 pages/min if T = 90 P = 1.5*90 = 135 ===================== C = k N 14 = k (4) k = 14/4 = 7/2 so C = 3.5 N if n = 7 C = 3.5 * 7 = 49/2 = 24.5
*September 9, 2014*

**Science**

I do not know the specific heat of water in obsolete units of BTU/(pound deg F). You do, use it in BTU heat input = Specific heat of water * 450 pounds * (104-60) degrees
*September 9, 2014*

**maths literacy**

circumference = 2 pi R
*September 9, 2014*

**Science**

Igneous gets spewed hot from the earth and solidifies as it cools. Sedimentary is deposited cool from oceans and streams and hardens with age and pressure. Your book must say something like that. see: http://geology.com/rocks/igneous-rocks.shtml and http://geology.about.com/cs...
*September 9, 2014*

**Calculus**

yes 20,000 (1.075)^10
*September 8, 2014*

**physics**

u = 20 cos 30 until it hits the ground. Vi = initial vertical velocity = +20 sin 30 = +10 initial vertical displacement = 45 final vertical displacement = 0 0 = 45 + Vi t - 4.9 t^2 solve for t v = Vi - 9.8 t solve for v speed = sqrt (u^2 + v^2)
*September 8, 2014*

**Math**

y = 800 * 2^(x/4) ??? ln y = ln 800 + (x/4) ln 2 (x/4) ln 2 = ln (y/800) x = ln (y/800)^4 / ln 2
*September 8, 2014*

**math**

(4/sqrt 2)(sqrt 2/sqrt 2) = (4/2)sqrt 2 = 2 sqrt 2
*September 7, 2014*

**AP Physics C**

oh, put all those in units of b, city blocks :)
*September 7, 2014*

**AP Physics C**

Well, you will have to draw the map for displacements add x components and y components separately and for distances: find each and add move 1 distance = 6.3 displacement east = -6.3 i displacement north = 0 j move 2 distance = 4 displacement east = -4 cos 40 = -3.06 i ...
*September 7, 2014*

**Quick math help**

1. AC= 3x+6 and CD=2x+14 x=_______ AC=______ Answer: x=8 AC= 30 yes :) ============= 2. AC= 5x-8 and CD=16-3x x=______ AD=_____ Answer: x=3 What will AD be because I'm sooo confused on how to work it out.. ========================== 5x-8 = 16-3x 8 x = 24 x = 3 AD = 5x-8+16...
*September 7, 2014*

**English**

Yes it is it would be better if two sentences :) or Yes it is a run on sentence. It would be better to write two sentences.
*September 7, 2014*

**Algebra**

w (2w-1) = 21 2 w^2 - w - 21 = 0 (2 w -7)(w+3) = 0 w = 7/2 = 3.5 then L = 6
*September 7, 2014*

**Math**

-4 (10) = -40 -4*2 = -8 so -40 = -8 - 4 N 40 = 8 + 4 N 4 N = 32 N = 8
*September 7, 2014*

**physics**

v = Vi + a t 0 = 60 -10 t because v = 0 at top t = 6 seconds at top then h = 0 + Vi t +(1/2)a t^2 h = 60 (6) - 5 (36) h = 360 - 180 = 180 meters or simply average speed up = 60/2 = 30 m/s 30 m/s * 6 seconds = 180 meters
*September 7, 2014*

**college physics**

Galileo says: Who cares what the mass is ? How far does anything fall in 2.4 s if dropped on a planet where g = 9.81 m/s^2 ?? d = (1/2) a t^2 d = (1/2)(9.81) (2.4)^2 (b) d = 4.1 4.1 = (1/2) (9.81)(t^2) solve for t v = Vi + a t v = 0 + 9.81 t (c) v = 0 + 9.81 t = 9.81 (1.7) Now...
*September 7, 2014*

**physics**

v = 0 + a t 11 = a (2.58) a = 11/2.58 d = (1/2) a t^2 = (1/2)(11/2.58) (2.58)^2 or simply =the average speed = 5.5 5.5 * 2.58 will give the same answer :)
*September 7, 2014*

**Physics**

final momentum = initial momentum book moves in + direction, man moves in - direction 2*11.1 + 84.9 v = 0 v = -22.1/84.9
*September 7, 2014*

**Calculus**

if f(x) = x^.5 then f(x+h) = (x + h)^.5 [f(x+h) - f(x)]/h = [(x+h)^.5-x^.5]/h binomial expansion of (x+h)^.5 = x^.5 + .5 x^-.5 h ..... higher powers of h so [ x^.5 + .5 x^-.5 h ...-x^.5 ]/h or .5 x^-.5 + higher powers of h = .5 x^-.5 as h --->0 if x = 121 f(x) = 121^.5 = 11...
*September 7, 2014*

**The Curriculum**

I am tempted to say: "All of the above", but would probably guess C.
*September 7, 2014*

**The Curiculum**

You are welcome :)
*September 7, 2014*

**The Curiculum**

Agree.
*September 7, 2014*

**The Curiculum**

Oh come on, guess and we will argue about it.
*September 7, 2014*

**math**

I do not know what your problem looks like.
*September 7, 2014*

**math**

length 5x ends 4x by 3x two sides 5x by 4x -->2*5x*4x = 40x^2 top and bottom 5x by 3x --> 2*5x*3x = 30x^2 two ends 2*4x*3x =24x^2 so 94 x^2 = .94 x^2 = .01 x = .1 .5 * .4 * .3
*September 7, 2014*

**teaching in early childhood programs**

looks like exploratory play to me, but my thing is physics.
*September 7, 2014*

**•teaching in early childhood programs**

I would have said D because they talk about influencing how the kids move around.
*September 7, 2014*

**teaching in early childhood programs**

I would choose C but your guess is as good as mine.
*September 7, 2014*

**teaching in early childhood programs**

I would not make statement C.
*September 7, 2014*

**Math**

2 w + L = 40 so L = 40-2w A = w L = w (40-2w) -2 w^2 + 40 w = A w^2 - 20 w = -A/2 w - 20 + 100 = -(1/2)(A-200) (w - 10)^2 = -(1/2)(A-200) w = 10, L = 20, A = 200
*September 7, 2014*

**maths**

area = 1200 = x^2 + 4 x h so h = (1200-x^2)/4x v = x^2h v = (1/4)x(1200-x^2) dv/dx 0 at min or max 0 = x(-2x) + 1200 - x^2 3 x^2 = 1200 x^2 = 400 x = 20 h = 400/80 = 5 v = 400 *5 = 2000
*September 7, 2014*

**maths**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*September 7, 2014*

**geometry - need help with this.**

a+b = 90 a = 4 b 5 b = 90 b = 18 a = 4*18 = 72
*September 7, 2014*

**Math**

20 for 1.00 then 4*.80 = 3.20 for 21 through 100 so 4.20 for 100 y = 4.20 + .03 (x-100) y = .03 x - 1.20
*September 7, 2014*

**Engineering**

yes, the zero derivative can be either a maximum or a minimum If x = 6, we have the minimum, in fact zero If x = 2, it seems we have a maximum which is the answer you want.
*September 6, 2014*

**Law of Sines**

sin A/15 = sin 35/9 = .0637 sin A = .956 so A = 72.9 degrees or 180-72.9 = 107.1 then A + B + C = 180 72.9 + B + 35 = 180 B = 72.1 degrees (One answer) sin B/b = .0637 so b = 14.94 or A = 107.1 then B = 180 - 35 -107.1 = 37.9 degrees (alternate answer)
*September 6, 2014*

**physics**

(1/2) m Vnew^2 = (1/2) m Vold^2 + W
*September 6, 2014*

**Physics**

v = Vi - 9.81 t at top, v = 0 t = 8 / 9.81 (b) h = 1.5 + 8 t -(1/2)(9.81) t^2 (c) at 2.4 m, new t 2.4 - 1.5 = 8 t - 4.9 t^2 then v = 8 - 9.81 t
*September 6, 2014*

**Physics for Technology**

What is the momentum of a hammer of mass 0.8kg striking a nail at 5 m/s2? So, p = m v p = (0.8)(5 m/s) p = 4 kg-m/s note velocity is meters/seconds, acceleration is m/s^2 A nail stops the hammer in 0.08 seconds: what force is delivered to the nail? NEWTON #2 Force = rate of ...
*September 6, 2014*

**Physics Help!!!!**

going forward faster and faster going forward but the brakes are on going backward faster and faster going backward but the brakes are on
*September 6, 2014*

**Teaching 4Grade Math**

If you save 5% the first week you are down to 95% If you then save 5% of that the second week you are down to 95% of 95% = .9025 or at 90.25% of full charge which means you saved (1/2)(1-.9025)(100) = 4.875% per week on the average. That is hardly fourth grade. It is more in ...
*September 6, 2014*

**Math**

3/10 are boys 7/10 are girls total boys = x total girls = x+200 total students = 2x+200 (3/10)(2x+200) = x 6 x + 600 = 10 x 4 x = 600 x = 150
*September 6, 2014*

**math 1 question**

yes 2.5 times r = 2.5 r
*September 6, 2014*

**Math**

1.45 c = 79.95 c = 79.95/1.45
*September 5, 2014*

**ALGEBRA**

five and six is eleven (x+5)(x+6) seven - two (x-7)(x+2) I bet you mean 9x^2-16 which is difference of two squares a^2-b^2 = (a+b)(a-b) (3x+4)(3x-4)
*September 5, 2014*

**Physics**

v = Vi - 9.81 t 20 = Vi - 9.81 (2.1) solve for Vi then Use that Vi to get v at t = 4.7
*September 5, 2014*

**physics**

east components 2880 cos 42 = 2140 south components 2880 sin 42 + 4360 = 6287 magnitude = sqrt (2140^2+6287^2) tan (angle) = 6287/2140
*September 5, 2014*

**Physics**

I mean west is - x direction :)
*September 5, 2014*

**Physics**

West is - y direction Ax = -20.0km*sin(35.0º) NOTE NEGATIVE Ay = 1.650km or 20.0km*cos(35.0º)? Bx = 18.0km*cos(75.0º) By = 1.420km or 18.0km*sin(75.0º)? Rx = Ax + Bx Ry = Ay + By and Rz = 1.650 - 1.420 R = sqrt (Rx^2 + Ry^2 + Rz^2)
*September 5, 2014*

**INTEGRAL CALCULUS PLEASE HELP!!!**

I assume you mean the integrals or areas are 4 , 9 and 1 Sketch it all I can say is that the integral from 4 to 17 (not 9 to 17) is -12 because 4 + integral 4 to 17 + 9 = 1 I do not even know what 2) means. If it is integral F(x) dx - 4 intregral dx then answer above - (4(17...
*September 5, 2014*

**Physics**

On earth that 40 N weight would correspond to about m = W/g = 40/10 = 4 kilograms of mass which is around 8 pounds. This collie is actually a toy poodle. 200 kg ? That is about 450 pounds weight on earth which means the average patient stepped on the scale with her husband and...
*September 5, 2014*

**Algebra**

Just did, see below.
*September 5, 2014*

**Physics**

well, sure, but there is much more to it. As you stated the problem: x = (1/2) a t^2 so a = 2 x/t^2 or t = sqrt (2 x/a) but that is a gross oversimplification of what is going on with constant acceleration a if a = some constant acceleration v = Vi + a t where Vi is initial ...
*September 5, 2014*

**math**

hard to say
*September 5, 2014*

**algebra**

line of form y = m x + b m = (Y2/Y1)(X2-X1) = (4-0)/(2-1) = 4 check with other points (like (12-0)/(4-1) ) y = 4 x + b put a point in to find b 0 = 4(1) + b b = -4 so y = 4 x - 4
*September 5, 2014*

**algebra**

y = x (.658 - .000407 x) where is y = 0 ? at x = 0 and at x = .658/.000407 = 1617 ft long (that is part B) this is a parabola that crosses the x axis at 0 and 1617 so the vertex, max height, is halfway between at x = 808 what is the height? y = -.000407 (808^2) + .658(808) = ...
*September 5, 2014*

**math 101**

7.9 * sqrt 2
*September 5, 2014*

**English**

Does the second sentence not seem a bit strange? Does it need the word "ever" ?
*September 5, 2014*

**math**

5 3/12 - 3 10/12 is 4 15/12 - 3 10/12 is 1 5/12
*September 5, 2014*

**Math PLease help**

put in the form y = m x + b then m is the slope 3 y = -6 x + 12 2 y = -2 x + 4 y = -2 x + 4 y = -1 x + 2 -2 is not - 1 so not parallel -2 is not -1/-1 so not perpendicular
*September 5, 2014*

**Math PLease help**

6 x - 14 = 30 x + 54 + 28 assuming that = is a + 24 x = -96 x = -4
*September 5, 2014*

**Physics**

The first phase is easy if you have constant acceleration because the average speed until the stop is Vi/2 = 5 m/s t to stop = 148.3 / 5 = 29.7 seconds a = change in velocity/change in time = -10/29.7 = -.337 m/s^2 phase 2 displacement = 37.7 - 148.3 = -110.6 meters -110.6 = (...
*September 4, 2014*

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