Sunday

October 4, 2015
Total # Posts: 22,100

**calculus**

A = pi r^2 A/dr = 2 pi r (which is the circumference of course, draw a circle and a ring of thickness dr on the outside and look at the added area) if r = 5 dA/dr = 10 pi =================== this is most interesting if the radius is changing with time r = k t dr/dt = k dA/dt...
*December 17, 2014*

**physic**

power = work/time work = weight * distance up = 475*9.81*10 so power = 475*9.81*10 / 24 Joules/second or Watts divide by 1000 for kilowatts
*December 17, 2014*

**Math( Can you help me with starting this problem)**

dV/dr = area of surface = 4 pi r^2 so dV/dt = 4 pi r^2 dr/dt so dr/dt = (dV/dt) / (4 pi r^2)
*December 17, 2014*

**Physics**

If .392 Newtons is pulling it at constant speed then the friction is equal and opposite to the pull .392 = mu m g = mu (.2219)(9.81)
*December 17, 2014*

**Algebra**

height = 5 (L-10)(w-10)5 = 1760 (L-10)(w-10) = 352 L = 2 w (2w-10)(w-10) = 352 (w-5)(w-10) = 176 w^2 - 15 w + 50 = 176 w^2 - 15 w - 126 = 0 (w-21)(w+6) = 0 so w = 21 L = 42
*December 17, 2014*

**Algebra 1**

slope = m = 3 10 = 3 (2) + b b = 4 y = 3 x + 4
*December 17, 2014*

**Physics**

If the angle is 90 degrees to the x axis it is all y axis 0 i + 9 j
*December 17, 2014*

**Science-Physics**

500 * 5 force in direction of motion times distance moved
*December 17, 2014*

**physics**

300 * 9.81 * 6 Joules
*December 17, 2014*

**Physics**

500 cos 37 - .5 (350 + 500 sin 37) = m a m = 350/9.81 find a 4 = (1/2) a t^2 for part be find mu for: 500 cos 37 - mu (350 + 500 sin 37) = 0
*December 17, 2014*

**Physic**

potentials add Q1/r = Q2/(.5-r)
*December 17, 2014*

**physics**

g = 9.81 m/s^2
*December 17, 2014*

**Physics**

51 = 4.9 t^2 solve for t d = 31 t v = 9.81 t vertical and 31 horizontal so speed = sqrt ( v^2+31^2)
*December 17, 2014*

**Physics**

angular speed = 2 pi(1.15/4.5) = omega v = omega * r = omega * 5.50 F = m a = m v^2/r = .655(v^2)/5.50
*December 17, 2014*

**physics**

(g - v^2/r) = .8
*December 17, 2014*

**math**

360,000 / 600 = = 3600/6 = 600
*December 17, 2014*

**Physics**

T - mg = ma T = m (g+a) = 2.13 (9.81 + 3.10)
*December 16, 2014*

**Math**

R + J = 48 J = .5 R + 6 R + (.5 R + 6) = 48 1.5 R = 42 etc
*December 16, 2014*

**math**

5 x + 3 y = 3213 y = 4 x 5 x + 12 x = 3213 17 x = 3213 x = 189 for digital 4 x = 756 for video sum = 945
*December 16, 2014*

**pre-algebra**

(-1)(-x) = (-1)(-7) +x = + 7
*December 16, 2014*

**algebra**

a = A e^rt a = 400 e^.076(1.5) a = 448.
*December 16, 2014*

**chemistry**

density ice = 4.3/5 = .86 g/cm^3 density of that oil = 27/30 = .9 g/cm^3 the ice is less dense than the oil. It will float
*December 16, 2014*

**Math**

x = log5 (27) 5^x =27 = 3^3 log3 (3^3) = log3 (5^x) 3 log 3 (3) = x log3 (5) but log 3 (3) = 1 so 3 = x log3 (5) log3 (5) = 3/x and y = log3 (5) so y = 3/x x y = 3
*December 15, 2014*

**physics**

V = omega r = 255 (.320) 382 = (1/2)V t because distance = average speed time time if a is constant solve that for t t = 764 / V 382 = (1/2) a t^2 solve for a, LINEAR aceleration alpha = angular acceleration = a/r
*December 15, 2014*

**physics**

mu m g = 88 = m g mu = 88/(32.1*9.81)
*December 15, 2014*

**algebra**

no solution 15 y = 15 y + constant
*December 15, 2014*

**astronomy**

Well, if it is a pine forest I suppose you are somewhere around 42 degrees north latitude Take a guess at 22 degrees south declination at Dec 22 add your latitude to that for example if 42 degrees north latitude the sun is 42 + 22 = 62 degrees below straight up at noon on the ...
*December 15, 2014*

**algebra**

anything except 1/0 times 0 is 0
*December 15, 2014*

**math**

when you eat half of something you multiply by 1/2 (which is the same as dividing by two)
*December 14, 2014*

**physics**

m1 = 428/9.81 m2 =195/9.81 195 - T = m2 a T = m1 a so 195 - m1 a = m2 a a = 195 /(m1+m2) which we should have said without doing all that
*December 14, 2014*

**physics**

a/g = .258 because mu m g = m a
*December 14, 2014*

**physics**

h = 6.52/sin 19.8 loss of potential E = m g h (1/2) m v^2 = m g h + (1/2) m (2.24)^2 m cancels v^2 = 2 g h + 2.24^2
*December 14, 2014*

**calc urgent**

It lies on the 45 degree line by symmetry so all we need to do is find the y coordinate, the mass does not matter, only uniform density call it 1 mass = 1/4 pi (1)^ 2 = pi/4 divide moment by this in the end moment about x axis of strip at y of width dy = y (x dy) integrate ...
*December 14, 2014*

**algebra**

let z = x^2 -3 z^2 + 27 z + 1200 = 0 divide by -3 z^2 - 9 z - 400 = 0 (z-25)(z+16) = 0 z = 25 ---> x = 5 or -5 z = -16 --> x = 4 i or -4i
*December 14, 2014*

**math**

100 (572-498)/498
*December 14, 2014*

**Math**

2*2*2*11 http://www.mathwarehouse.com/arithmetic/numbers/prime-number/prime-factorization.php?number=44
*December 14, 2014*

**gen chem**

1.38*10^3 I assume one mol Fe3O4 for every 4 mol H2 1380/4 = 345 mols of Ferric oxide 345 * (3*56+4*16) grams
*December 14, 2014*

**Social Studies**

Most say c.
*December 14, 2014*

**Algebra**

Vdownwind = v + 5 Vupwind = v - 5 5600 = (v+5) t 5600 = (v-5)(t+10) so 5600 = v t + 5 t 5650 = v t + 10 v -5 t ================ -50 = 0 +10 t -10 v or t = v-5 go back up 5600 =(v+5)(v-5) = v^2 - 25 v^2 = 5625 v = 75
*December 14, 2014*

**Math**

32 = 2^5 1 we can have 32 in a row 2 or 16*2 3 or 8 * 4 4 or 4 * 8 5 or 2 * 16 6 or 1 * 32 now of course different items can go in each of those spaces but that gives you an awful lot of choices.
*December 14, 2014*

**math**

K + ( K- 15 ) = 99 2 K = 99 + 15 = 114 K = 57
*December 14, 2014*

**chem**

AREA is NOT in cm^3 but in cm^2 Should I trust the rest of what you tyoed? Oh well 3 * 10^-6 meters(10^2 cm/m) = 3*10^-4 cm 3*10^-4 * .55*10^2 = 1.65*10^-2 cm^3 19.3 g/cm^3 * 1.65*10^-2 cm^3 = .318 g
*December 14, 2014*

**question**

yes, think so
*December 14, 2014*

**question**

Is it your fate to respond again, or is it your choice?
*December 14, 2014*

**question**

You are doing so right now.
*December 14, 2014*

**math**

to convert units, always multiply by something/the same thing in other units. For example there are ten gophs in one bork 10 gophs/ 1 bork is the same top and bottom so if I multiply by that or its inverse I change nothing. so if I have 15 borks and want to express that in ...
*December 14, 2014*

**Sixth Grade Math**

(1/4)^2 = (1/4)(1/4) = 1/16 (1/4)^3 = (1/4)(1/4)(1/4) = 1/64 etc
*December 14, 2014*

**Sixth Grade Math**

1/16 <1/4
*December 14, 2014*

**Sixth Grade Math**

2(55) + 2(88) + 2(40)
*December 14, 2014*

**Math Question**

25 + 64 = 79 = hypotenuse^2 in quadrant 2 and quadrant 4 because sin is - sin = 8/sqrt79 or -8/sqrt 79 cos = -5/sqrt 79 o 5/sqrt 79 etc, draw pictre
*December 14, 2014*

**Math**

35 (pi/180) 250 (pi/180)
*December 14, 2014*

**algebra 2**

2. 36 -4(9) = 36 -36 = 0 so repeated real root [ 6 +/- 0 ] / 18 = 1/3 and 1/3 (same, parabola just touches the x axis)
*December 14, 2014*

**algebra 2**

p^2 + 12 p + 4 = 0 b^2-4ac = 144 -16 = 128 positive so there will be two real roots [ -12 +/- sqrt(128) ] / 2
*December 14, 2014*

**algebra 2**

(b/2)^2 always :)
*December 13, 2014*

**Math**

amazing - it got the same thing I did :)
*December 13, 2014*

**Math**

here is the link Steve is sending you to (I went and looked( http://calc101.com/webMathematica/long-multiply.jsp
*December 13, 2014*

**Math**

(3x-7)(4x+3) = 12 x^2 -19 x - 21 now use distributive property 2x (12 x^2 -19 x - 21) -1 (12 x^2 -19 x - 21) = 24 x^3 - 38 x^2 - 42 x _________- 12 x^2 + 19 x + 21 =============================== = 24 x^3 - 50 x^2 - 23 x + 21
*December 13, 2014*

**Math**

slope = (y-5)/(x-2) = (0-5)/(3-2) = -5/1 or y - 5 = -5 (x-2) =========================== huh, it says the answer right in the sentence y = 10.5 x + 65
*December 13, 2014*

**physics**

P V = n R T
*December 13, 2014*

**physics**

delta L/34 = coef of expansion * delta T
*December 13, 2014*

**physics**

Force * time = change of momentum = 125 * 33 often called impulse Why on earth would a baseball player push on a baseball for 33 seconds? Is that a typo?
*December 13, 2014*

**math**

4 5 or 6 p(passed) = .6 p(failed) = .4 Binomial distribution for example for 4 of 6 passed C(6,4) .6^4 .4^2 C(6,4) = 6!/[ 4!(2!)] = 6*5/2 = 15 15 * .6^4*.4^2 = .311 do that also for 6,5 and for 6,6 and add those three results
*December 13, 2014*

**math**

I am going to assume that you mean [ (n^2-4)/(n^2-2n) ] * n/(n^2+10n+16 ) Immediately you can see that n = 0 and n = 2 are excluded from the domain, also if n^2+10 n + 16 = 0 which is if n = -2 or -8 now [(n-2)(n+2)/n(n-2)] *n /[(n+2)(n+8)] = 1/(n+8)
*December 13, 2014*

**precalculus**

if a denominator is zero, you have a vertical asymptote (look at 14 as x becomes 2) if the function becomes constant you have a horizontal. look at 14 as x gets big positive and as x gets big negative
*December 13, 2014*

**math**

14 1/3 = (14*3+1)/3 = 43/3 and 43/3 = 86/6 so 86 sixths
*December 13, 2014*

**History**

agree
*December 13, 2014*

**Algebra**

1 , x^2 , 9 x^2 - 1 = d -x^2 + 9 = d --------------- 0 + 8 = 2 d d = 4 so 1 , 5 , 9 x = sqrt(5)
*December 13, 2014*

**Geometry**

Remember anything with a pointy top and straight sides has volume of base area times height times (1/3) V = (1/3) pi r^2 h
*December 13, 2014*

**math**

10 h >/= 55 so h >/= 5.5 the top one, assuming she runs an average speed for the week :)
*December 13, 2014*

**Algebra**

a , a+d, a+2d ..... a+(n-1)d or an = a +(n-1)d a5 = a + 4 (1) = 11 so a = 7 7 * 8 = 64-8 :)
*December 13, 2014*

**algebra**

It is certainly off. Perhaps it means -16 t^2 + zero initial speed up + 34 feet high but it is impossible to be certain. Good luck. The only thing you can be sure of there is -16 t^2
*December 13, 2014*

**typo**

no way On earth in the ancient feet, inches, slugs, seconds system h = Hi + Vi t - 16 t^2 please get it right so someone can answer
*December 13, 2014*

**math**

Google says 5.6 lb/gal = oz/gal yields 5.6 lb/gal = 89.6 oz/gal which is what happens if you have 16 oz/ lb 16 *5.6 = 89.6
*December 13, 2014*

**statistics**

I suppose you would use the mean but a mean of 3.8 with a standard deviation of 17.4 is pretty strange. in general this is handy: http://davidmlane.com/hyperstat/z_table.html
*December 13, 2014*

**Physics**

distance = speed time time so wavelength = speed of sound * period T but f = 1/T so wavelength = speed of sound / f f = speed /wavelength look up speed of sound at 20 C in your book (different tables available)
*December 13, 2014*

**Geography**

Oh, thanks, I thought she maybe meant the waterfall looked like Abraham Lincoln with a full moon and therefore did not reply.
*December 13, 2014*

**Reiny or Steve can you help ?**

I can not.
*December 13, 2014*

**Algebra**

n</= 2t+3 ??? is that not any n equal to or greater than -3
*December 13, 2014*

**Physics**

You are welcome.
*December 13, 2014*

**Physics**

.05 m on a side volume = .05^3 = 125 * 10^-6 m^3 mass of water displaced = 10^3 kg/m^3 * 125*10^-6 m^3 = .125 kg Archimedes says force up = weight of water displaced g = 10 m/s^2 so m g = 1.25 Newtons
*December 13, 2014*

**scholarship 7th std**

try dividing 56324 by 12 then 54324 and get 4527 exact so 4
*December 13, 2014*

**algebra 2**

4 x^2 + 4 x - 15 = 0 x = [ -4 +/- sqrt(256) ]/8 = [ -4 +/- 16] / 8 =12/8 or 20/8 = 3/2 or -5/2 or (2x-3)(2x+5) = 0
*December 13, 2014*

**Algebra**

|a-b| = 20 - |b-c|-|c-a| If b>c and c>a |a-b| = 20 - b + c - c + a =20+(a-b) if a>b then a-b = 20 + a-b and a-b = 0 if a < b then b-a = 20 -b+a 2b-2a = 20 |a-b| = 10 try others but I think you will find 10
*December 13, 2014*

**science**

anything that is different at one end like F or A
*December 13, 2014*

**math**

+i +j +k +1 -2 -1 +3 -1 +1 ================== cross product (-3)i + (-4)j + (+5)k so yes V = -3 i - 4 j + 5 k opposite to that is also parallel +3 i + 4 j -5 k add any old point to that and it is still parallel
*December 13, 2014*

**Science**

Hey, really, in one sentence? This might help: https://www.caymanchem.com/app/template/chemAssistant,Tool.vm/itemid/4001
*December 13, 2014*

**math**

geometric series a + a r + a r^2 + a r^3 ... a r^10 a =19,000 r = 1.04 S = a (1-r^n)/(1-r)
*December 13, 2014*

**no idea**

I do not know what your question is? do you want the variation sigma^2 of that data set or something?
*December 13, 2014*

**Algebra 1**

It is always negative or 0 it is a straight line with slope of -1 It is -4 when x = 0 it is 0 when x = 4
*December 13, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*December 13, 2014*

**art**

Make an educated guess. I am sure you will be correct. http://www.pbs.org/faithandreason/gengloss/enlight-body.html
*December 12, 2014*

**algebra**

complete the square to find the vertex if you do not know calculus 16 t^2 -32 t -48 = -h t^2 - 2 t - 3 = -h/16 t^2 - 2 t = -h/16 + 3 t^2 - 2 t + 1 = -h/16 + 4 = -1/16(h-64) (t-1)^2 = -(1/16) (h-64) max height is vertex at t = 1 second and h = 64 ft c) t^2 - 2 t - 3 = 0 (t-3)(t...
*December 12, 2014*

**physics 1**

Yes, but be sure to use distances in meters not cm (1.61 meters apart)
*December 12, 2014*

**Physics**

Use conservation of momentum to get initial speed of bullet/block system (m+M)V = m v so V =mv/(m+M) calculate (1/2) (m+M) V^2 then (m+M) g h = (1/2) (m+M)V^2 calculate V then go back to v = (m+M)V/m
*December 12, 2014*

**Math**

You are looking for the sum of the series? r (not d usually, that is for arithmetic) = 3 not 1/3 a = 1/27 1/27 * 3 = 1/9 1/9 * 3 = 1/3 etc then for sum of first n terms a(1-r^n)/( 1-r ) If so, yes that is for the first n terms but watch out. If you want the sum for an infinite...
*December 12, 2014*

**Math**

sister has 2 n yes boy has arithmetic sequence a1 = 2 d = 2 an = a1 + (n-1) d = 2 + (n-1)2 or an = 2n sum from n = 1 to n = n S = (n/2)(a1+an) = (n/2 )(2 + 2n) S = n + n^2 you got twice as many somehow
*December 12, 2014*

**correction**

The formulas are for the END of the year so do it for 14 years, then add that 15th deposit of 3150 (tricky wording)
*December 12, 2014*

**Math Check!!**

You get e^rt for EACH deposit for its time t 3150 [ e^14(.04) + e^13(.04) + ....e^.04] I am sorry I do not know an easy way to do that
*December 12, 2014*

**Math Check!!**

sorry, no. Your formulas are for ONE deposit at the start, not for annual deposits. Look up "amount of a sinking fund" S = 3150[ 1.04^n - 1 ] /.04
*December 12, 2014*

**calculous (check)**

By the way, on earth I think it travels 16, not 13 feet with no air resistance in the first second and d = 32, not 26 but perhaps your book is on another planet.
*December 12, 2014*