Friday

August 22, 2014

August 22, 2014

Total # Posts: 17,967

**calculus help**

dy/dx = 9 integral dx/(1-x^2)^.5 y = 9 sin^-1 x + c note sin pi/6 = sin 30 deg = 1/2 so y(1/2) = 9 (pi/6) + c = 1 so c = 1 - 3 pi/2 so y = 9 sin^-1 x + (2-3 ) pi/2
*April 23, 2014*

**maths**

That is interesting. By the way you can not copy and paste here. I see no data. (and also no question)
*April 23, 2014*

**physics**

f = 1/T omega = 2 pi f A omega = .7 *2 pi f A omega^2 = .7 (2 pi f)^2
*April 23, 2014*

**Physics**

about time you did some. I passed the course in 1954.
*April 22, 2014*

**Physics**

d = .5 a t^2 840 = a(1024) a = .820 m/s^2 v = a t = .820 * 32 = 26.2 m/s
*April 22, 2014*

**algebra**

A=P(1+I)^3 You mean A=P(1+I)^t t just happens to be 3 years here 49130 = 40960 (1+i)^3 1.19946 = (1+i)^3 take cube root 1 + i = 1.0625 or i = 6.25 %
*April 22, 2014*

**Physics waves- help please**

You hear a high pitch as he comes toward you, lower as he leaves So the actual frequency is lower than you hear. In fact you know it is between 195 and 147 Fl = [(v + vl)/(v+vs) ] Fs where Fl = frequency heard Fs = Frequency of source v = v sound vl = v listener vs = v source ...
*April 22, 2014*

**Algebra**

b^2 = + 5/2 b = +/- sqrt (2.5)
*April 22, 2014*

**Physics**

v = vi + a t x = xi + vi t + (1/2) a t^2 for example "Place the man so that he is positioned at the 0.00 metre (m) mark. Set the initial velocity at -2.00 m/s and the acceleration at 0.50 m/s2. In a data table, record the time when the man is momentarily stopped and ...
*April 22, 2014*

**Science**

see saw heavy person on one end light person on the other end. put the pivot at the center of mass so it balances. Ignoring the mass of the plank itself heavy mass (distance to c mass) = light person mass (distance to c mass) in general sum of m1 x1 + m2 x2 +....mi xi = (m1 + ...
*April 22, 2014*

**Math**

hypotenuse^2 = 18^2 + 22*2
*April 21, 2014*

**calc**

(1/2) b h = A (1/2) b (11.5) = 85 b = 14.8 if we need it 2 dA/dt = b dh/dt + h db/dt 2 (3) = 14.8 (1) + 11.5 db/dt - 8.8 = 11.5 db/dt db/dt = - .765
*April 21, 2014*

**Calc**

LOL, math versus physics, round 4596
*April 21, 2014*

**Calc**

dy/dt = dy/dx * dx/dt dy/dx = 4 (1/2) (2x+2)^-.5 (2) = 4(2x+2)^-.5 dx/dt here = 5 so dy/dt = 20 (2x+2)^-.5 = 20/2 = 10 so velocity vector at (1,8) is V =5 i + 10 j the radius vector here is R =1 i + 8 j I want the component of the velocity vector in the direction of the radius...
*April 21, 2014*

**College Algebra**

do you mean n = c e^(at) ? I will assume that. when t = 0 , e^at = e^0 = 1 so c = 148 whet t = 2 333 = 148 e^(2a) 2.25 = e^(2a) so ln 2.25 = 2 a .8109 = 2 a a = .405 so n = 148 e^(.405 t)
*April 21, 2014*

**calculus help**

well, first I factor it to see where zeros of the numerator and denominator are: (2x+3)(x-4) / [ (3x-1)(x-2) ] so you know the thing is going to be undefined at x = 1/3 and at x = 2 Now where are derivatives + , - and 0 ? If you use this you get a graph https://www....
*April 21, 2014*

**physics**

.01 meter/900 = 1.11*10^-5 meters` sin T = T = 664*10^-9/1.11*10^-5 = .0598 .0598 * 2.75 = .164 meters
*April 20, 2014*

**physics**

Y1 = lower right wall tan i = Y1/(L/2) Y1 = (L/2) tan i Y2 = upper right wall = L-Y1 = L - (L/2) tan i or Y2 = L (1 - .5 tan i) now in upper triangle tan i = L(1 - .5 tan i)/.8 L or tan i = 1.25 - .625 tan i 1.625 tan i = 1.25 tan i etc
*April 20, 2014*

**Maths**

F = T + 10 F + 3 = 3(T+3) T + 10 + 3 = 3 T + 9 2 T = 4 T = 2 F = 12
*April 20, 2014*

**Physics waves**

2 I have no idea if the nodes at the end count as two of the three I will assume yes so we have one node in the middle, the second harmonic Adjacent nodes are (1/2) lambda apart so the length of the string is a wavelength
*April 20, 2014*

**Physics waves**

1) 3 Hz, the difference frequency sin a + sin b = 2 sin .5(a+b) cos.5 (a-b) or twice the average frequency times half the difference frequency YOU HEAR TWO maxima per cycle (he square of the amplitude so you hear F1-F2 nor (1/2) (F1-F2)
*April 20, 2014*

**math (cant figure it out)**

Activity Boys Girls Total Walk------ 3--- 6 ---> 9 Bike------ 5--- 3 ---> 8 Skateboard 2 ---1 ---> 3 Total------10---10---> 20 ______________ What percentage of the total students chose skateboarding? 100 (3/20) = 15% so yes, none of these 10% 20% 30% none of these...
*April 20, 2014*

**Physics waves- check answers please**

You are welcome.
*April 20, 2014*

**Physics waves- check answers please**

I agree on all but #3. If by loop they mean antinode they occur 6 times including the ends. The distance from a node to an antinode is 1/4 lambda. I see ten quarter wavelengths in the 24 feet so 10( lambda/4) = 24 lambda = 2.4 *4 = 9.6 meters
*April 20, 2014*

**physics**

Generally yes, when you cook something the temperature goes up, storing heat that can be released later when the fire goes out.
*April 20, 2014*

**Social Studies**

I should have said between Iraq, Turkey, Syria, and Iran.
*April 20, 2014*

**Social Studies**

When the Middle East was split up into "mandates" under European countries after the Ottoman Empire was demolished, little attention was given to the ethnic or historical backgrounds of the various groups of people. Lines were arbitrarily drawn and this was called &...
*April 20, 2014*

**Social Studies**

Once again - C
*April 20, 2014*

**Dynamics**

at top of loop centripetal acceleration = g or it leaves the track g = v^2/a height at top of loop = 2 a potential energy at top of loop = m g h = 2 m g a total energy at top of loop = .5 m v^2 + 2 m g a = .5 m g a + 2 m g a = 2.5 m g a so h = 2.5 a
*April 20, 2014*

**math**

for combinations: n!/[r!(n-r)!] 6! /[ 3! (6-3)! ] 6*5*4/ (3*2*1)
*April 20, 2014*

**SPAM**

Some of these are virtually identical and some are terribly easy. Try them before posting.
*April 20, 2014*

**Chemistry**

OOps sorry, thinking atomic number :(
*April 20, 2014*

**Chemistry**

1.2 * 5 grams/ liter = 6 grams/liter Na = 11 g/mol Cl = 35.5 g/mol Na Cl = 46.5 g/mol 6/46.5 = .129 M
*April 20, 2014*

**statistics**

.4686 http://davidmlane.com/hyperstat/z_table.html
*April 20, 2014*

**physics**

60,000 m/3600 s = 16.7 m/s 80,000 m/3600 s = 22.2 m/s (16.7 - 22.2)m/s / 5 s = -1.11 m/s^2
*April 20, 2014*

**Physics**

I am not sure I have ever seen a really watertight shipping container but anyway:) Volume of container = 6*2.2*2.3 = 30.36 m^3 Buoyancy of container = 30.36*1025 g N = 31,119 g N Buoyancy of lift bag = 1025 g (4/3) pi r^3 = 21,094 g N total up force = 52,213 g N total down ...
*April 19, 2014*

**Physics**

d bus = .5 a t^2 = .25 t^2 d student = d bus + 10 = 3 t so .25 t^2 = 3 t - 10 .25 t^2 -3 t + 10 = 0 t^2 - 12 t + 40 = 0 t = [ 12 +/- sqrt(144 -160) ] /2 oh my, complex t student only catches bus in imagination
*April 19, 2014*

**Physics**

22,000/3600 = 6.11 m/s 85 000/3600 = 23.61 m/s average speed during acceleration = 14.86 m/s t = distance/speed = 200/14.86 = 13.46 s a = speed change/time = 17.5/13.46 = 1.3 m/s^2
*April 19, 2014*

**Calculus Help**

b) the answer is in (a) twice 2178 feet I think you can figure the rest out
*April 19, 2014*

**Calculus Help**

90 mi/hr = 132 ft/s (a) first how long and how far to reach 132 ft/s v = 0 + 4 t 132 = 4 t t = 33 s to reach 132 d = .5 a t^2 = 2 (33)^2 = 2178 ft to reach cruising speed 15*60 = 900 seconds total 900 - 33 = 867 seconds left how far at cruising speed 132 ft/s * 867 s = 114,...
*April 19, 2014*

**calculus help**

Nothing. I use SCI unless ordered otherwise :)
*April 19, 2014*

**calculus help**

4.14 m/s^2 = 13.6 ft/s^2 :)
*April 19, 2014*

**calculus help**

22 mph = 9.83 m/s 50 mph = 22.35 m/s a = change in velocity/time = (22.35 -9.81)/3 = 4.18 m/s^2 or about half g
*April 19, 2014*

**math**

a) y = 1 x - 3 slope = m = 1 slope of perpendicular = -1/m = -1/1 = -1 so y = -x + b 2 = -3 + b b = 5 so y = -x + 5 do the other the same way
*April 19, 2014*

**SkatingDJ**

It must be numbered 0 to 5. Never heard of that before. odd = 1 3 5 even = 0 2 4 prob of odd = 1/2 colors = 2 y + 1 b + 1 g so prob y = 2/4 = 1/2 the two events are independent so p = (1/2)(1/2) = 1/4
*April 19, 2014*

**math**

r^2 = k V k = r^2/V if you multiply r by 9, then V by 81 k = (9r)^2/81V = r^2/V so e
*April 19, 2014*

**Physics**

LOL - are you sure all the charges are the same Stephanie ?
*April 19, 2014*

**physics**

You are welcome :)
*April 19, 2014*

**physics**

half the area is twice the speed V1 = 1 m/s V2 = 2 m/s Bernoulli (1/2) rho V1^2+P1 = (1/2) rho V2^2+P2 rho water =1000 kg/m^3 2921 Pa is very low by the way, like 1 atm = 100,000 Pa for example. Perhaps they mean gage pressure. 500 (1)^2 + 2921 = 500 (2)^2 + P2 2921 - P2 = ...
*April 19, 2014*

**Math**

Part A: How many oxygen atoms are there in 50 atoms? ======================= Huh ? perhaps you mean in 50 molecules? I will assume that 1/4 * 24 = 6 Oxygen atoms / molecule 6*50 = 300 in 50 of them If there are 6 in one then there are 300 in 50
*April 19, 2014*

**math**

6770 *60/6.4 = 63,470 feet/minute By the way those of us who work at sea figure about 5 seconds per nautical mile. Some lighthouses flash at the same time as they sound a horn. If you hear the horn five seconds after you see the flash, you are a mile away from the lighthouse.
*April 19, 2014*

**Physics**

F = m a CONSTANT acceleration requires constant force.
*April 19, 2014*

**Linear programming**

x = days at Loc 1 y = days at Loc 2 then limits and intecepts deluxe 10x+20y >/= 2000 (0,100)(200,0) better 20x+50y >/= 4200 (0,84)(210,0) standard 13x+6y >/= 1200 (0,200)(92.3,0) graph those and cost constraint c = 500 x + 800 y Now test upper corners try (0,200) all...
*April 19, 2014*

**mathematics**

see if this helps: http://davidmlane.com/hyperstat/z_table.html
*April 18, 2014*

**Calculus Help Please Urgent!!!**

square side = x triangle side = y perimeter = 4 x + 3 y = 14 area = x^2 + sqrt3 (y^2)/4 x = (14 - 3 y)/4 area = (196 - 84 y +9y^2)/16 + 4 (3^.5)y^2/16 = [1/16] (196 - 84 y + 15.93 y^2) dA/dy = 0 for max or min 0= -84 y + 31.86 y^2 so y = 0 or y = 2.63 so x = 14/4 or 1.528 so 4...
*April 18, 2014*

**Math**

I have no idea. It depends on the pressure in the ball and the temperature. P V = n R T so n = moles of He = P V/ (RT) = P (4/3)r^3 /(RT) a mol of He has mass of 4 grams
*April 18, 2014*

**Math**

tan^-1 (.25) = 14 deg
*April 18, 2014*

**Math**

You can not copy and paste so I do not see your choices but tan E = 20/d d = 20/tan E
*April 18, 2014*

**MATH FACTOR POLYNOMIALS**

I was looking for what with 3 would make 2 and it is one.
*April 18, 2014*

**MATH FACTOR POLYNOMIALS**

+3-1 = +2 so (x+3)(x-1)
*April 18, 2014*

**Applied mathematics**

14/8 apple 11/8 orange 9/8 cranberry = 34/8 = 4 1/4
*April 18, 2014*

**math**

Go ahead, try to make a tile floor out of regular pentagon tiles
*April 18, 2014*

**Social Studies**

I would say C The British should have split the Kurds off after WW 1 since they really do not belong with the Iraqis or the Turks.
*April 18, 2014*

**Physics**

2 cars pulling together on level surface? Mass of cars = 3800 kg weight of cars = 3800*9.81 = 37278 N so max friction force of tires = 37,278 N mass of full vault =38803 kg weight of full vault = 380,657 N max retarding friction = .57*380657 = 216,974 N In other words, based ...
*April 17, 2014*

**History HELP! ASAP**

Each of your questions requires an essay to help you and perhaps if you try to write them someone here can help with them. In this case I might concentrate on the interaction of England, France, US colonies and Iroquois and Algonquins. In the other question I would discuss ...
*April 16, 2014*

**science**

m g h = Potential energy at top = 822 60 (9.81) h = 822 h = 1.4 meters
*April 16, 2014*

**calculus help**

https://www.wolframalpha.com/input/?i=derivative+of+x^2%28x%2B3%29%2F%28x%2B1%29^3 6x / (x+1)^4
*April 16, 2014*

**calculus help**

then do it again :)
*April 16, 2014*

**calculus help**

[(x+1)^2 (3 x^2)-x^3 (2)(x+1)] /(x+1)^4 [(x+1)(3x^2) - 2 x^3 ]/ (x+1)^3 [ 3 x^3 + 3 x^2 -2 x^3 ] / (x+1)^3 [ x^3 + 3 x^2] /(x+1)^3 x^2 (x+3) / (x+1)^3
*April 16, 2014*

**calculus help**

https://www.wolframalpha.com/input/?i=derivative+of+%28x^3%29%2F%28%28x%2B1%29^2%29+
*April 16, 2014*

**Math**

how many cups in a gallon? 16 so 2 cups concentrate + 16 cups water = 18 cups lemonade so concentrate / lemonade = 2/18 = 1/9 now how many ounces in a pint (a pint is a pound the world around :) 16 so 1/9 =x/16 x = 16/9 = 1.78 oz
*April 16, 2014*

**SS**

Build factories, farms, houses providing residents with jobs.
*April 16, 2014*

**calculus help**

Play with this: https://www.wolframalpha.com/input/?i=derivative+of+1%2B%281%2Fx%29%2B%285%2Fx^2%29%2B%281%2Fx^3%29+
*April 16, 2014*

**Optics - sorry, not I **

sorry, optics is not my thing at all :(
*April 16, 2014*

**calculus help check and help**

a) calculate lim t->infinity (v. answer: mg/c ----->what is the meaning of this limit ============================== It is the "terminal velocity" (Google that) which is the speed where the drag force equals the weight. One uses a parachute so that one's ...
*April 16, 2014*

**physics**

a = change in velocity/time = (0 - 43)/.28 = - 154 m/s^2
*April 16, 2014*

**Geometry**

for similar figures areas scale with the square of lengths so sqrt(4/49) = 2/7
*April 16, 2014*

**math**

1.025^10 = 1.280084544 * 5000 = 6400.42
*April 16, 2014*

**calculus**

http://www.mathsisfun.com/data/function-grapher.php f' = 7 e^7x - e^-x when is that zero? 7 e^7x = e^-x 7 e^8x = 1 e^8x = 1/7 8 x = ln(1/7) x = -.243 at min
*April 16, 2014*

**calculus help**

try : https://www.google.com/search?q=graph+ln%28x%29+from+1+to+6&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb ln 6 = 1.79 ln 1 = 0 ln 6 - ln 1 = 1.79 1.79/5 = .36 approx ln x = .36 e^ln x = ? = e^.36 so x = 1.43 sure enough between 1 and 6 :)
*April 16, 2014*

**Algebra**

2 (a+1) / [(a+1)(a-1)] for starters :)
*April 15, 2014*

**Geometry- trig ratio**

sin 55 = 21,000/hypotenuse we want that hypotenuse
*April 15, 2014*

**science**

you want traction, not slipping, so increase friction.
*April 15, 2014*

**Math**

sin 10 = PR/16 PR = 16 sin 10
*April 15, 2014*

**Algebra**

You are welcome. You could have done this by long division but often you can see the factors more quickly.
*April 15, 2014*

**Algebra**

2 x^3 – x^2 – 24 x + 12) = (2 x^3 -24 x) - (x^2 - 12) = 2 x (x^2-12) - 1 (x^2-12) = (2x-1)(x^2-12) now divide that by (2x-1) :)
*April 15, 2014*

**Math**

sin 10 = PR/16 PR = 16 sin 10
*April 15, 2014*

**Math**

1.05^2 - 1 = 10.25 APY Wilder 1.0081666^12 - 1 = 10.2524 APY Cheapskate so go with cheapskate ten years 1.05^20 =2.6532 *85,000 = 225,530.30 1.0008166667^120 = 2.65387 *85,000 = 225,579.18 Cheapskate is 48.88 better
*April 15, 2014*

**english**

The magnificent king emerged victorious eliciting a groan from his opponent who had been deserted by his muses depriving him of the strength of his convictions :-)>
*April 15, 2014*

**Geometry - Area**

You are welcome :)
*April 15, 2014*

**Geometry - Area**

find the area of each of the 6 equilateral triangles making up the hexagon Each side of triangle = 12 yards { by the way, first check apothem length because it is our altitude ) tan 30 = (1/2)(12)/apothem apothem = 6/tan 30 = 10.4 - sure enough, whew } so area of triangle = (1...
*April 15, 2014*

**math**

5 * .011 * p = 82.5
*April 15, 2014*

**math**

10 * .025 * 5000 5000 + part A (ignoring inflation :)
*April 15, 2014*

**chemistry**

Use google for conversion 1500 mm Hg = 1.97368421 atm = 199 983.553 pascals
*April 15, 2014*

**Algebra II**

In other words you did one of 120 sequences that yield 7 successes out of 10 trials.
*April 15, 2014*

**Algebra II**

....but the probability of failure is not independent of the probability of success :)
*April 15, 2014*

**Algebra II**

binomial distribution p(sucess) = 12/15 = 4/5 = .8 1-p = 1/5 = .2 n = 10 k = 7 P(x=7) = C(10,7) * .8^7 * .2^3 C(10,7) = 10!/[ 7! (3!) ] = 10*9*8 / (3*2) = 80*9/6 = 120 so P = (120)(.8^7)(.2^3) = 0.201
*April 15, 2014*

**geometry**

100 = 4x^2 25 = x^2 x = 5 or -5 but if you really want to use formula x^2 + 0 x - 25 = 0 x = [ -0 +/- sqrt (0 + 100) ] / 2 x = +/- 10/2 x = +/- 5
*April 15, 2014*

**math (matrix)**

I assume you meant the determinant 24 x + 3 x^2 + 6 x + 10 - 9x = 25 3 x^2 + 21 x -15 = 0 x^2 + 7 x - 5 = 0 x =-7/2 +/- (1/2) sqrt(69) What a mess, assume you have a typo. To invert matrix use http://matrix.reshish.com/inverse.php
*April 15, 2014*

**math**

100 * (1/8)/ (8/12+3/12) = 100 * (1/8) / (11/12) = 100 * (3/24)(22/24) = 100 (3/22) = 13.6%
*April 13, 2014*

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