Tuesday

September 2, 2014

September 2, 2014

Total # Posts: 18,212

**Physics**

The loudness is the amount of power passing through a square meter of area surrounding the source. As you get further from a constant power source, the loudness decreases because the area of a sphere surrounding the source increases. ( You know that. As you get further from a ...
*June 5, 2014*

**physics**

get V from momentum (75 + 52) V = 75 (1.8) calculate V calculate (1/2) m V^2 friction force = .042 * m * g friction force * distance = (1/2) m V^2 or actually m cancels .042 g d = .5 V^2
*June 4, 2014*

**physics**

(1/2) m v^2 = (1/2) k x^2
*June 4, 2014*

**physics**

Hey, you have done several of these now. Try
*June 4, 2014*

**Math**

cost per unit = cpu = C(x) / x = 36,100/x + 100 +.01 x d cpu/dx = 0 at min = -36,100/x^2 + .01 .01 x^2 = 36,100 x^2 = 3,610,000 x = 1900 units now go back and get cpu = 36,100/1900 + 100 + .01(1900) = 2019
*June 4, 2014*

**Math**

2 dimensional with 3 or more sides side angle
*June 4, 2014*

**Physics**

k = 30 N/.2 m = 150 N/m PE of spring = (1/2) k x^2 = 75(.04)=3 Joules normal force = m g friction force = .4 m g work done against friction = .2 *.4 * mg = .08*.25*9.81 = .196 Joules so Ke left = 3 - .196 = 2.8 Joules (1/2) m v^2 = 2.8 calculate v
*June 4, 2014*

**Precalculus**

6 letters if start with A so 5 left c(5,3) = 10 10 more start with I so 20 total others similar
*June 4, 2014*

**Precalculus**

2a 9*10*10 = 900 2b 4 * 5 * 5 2c 9 * 1 * 10
*June 4, 2014*

**Precalculus**

c(20,5) = 20!/(5!*15!) = 20*19*18*17*16 /(5*4*3*2) = 15504
*June 4, 2014*

**Precalculus**

1. NO The order does not matter, Disney first or white mountains first so COMBINATION C(20,5)
*June 4, 2014*

**Math**

x = 15 - 2y x^2 = 225 - 60 y + 4 y^2 F = 5 y^2 -60 y + 225 dF/dy = 10 y - 60 zero when y = 6 then x = 3 is that min or max? d^2F/dy^2 = 10 so it is min F here = 9+36 = 45 check ends if x = 0 y = 7.5 and F = 56 1/4 if y = 0, x=15 and F = 225 ok, done
*June 4, 2014*

**Math - Business Calc.**

Hey, use that h, calculate L and w find L W h
*June 4, 2014*

**Math - Business Calc.**

L = 17 - 2 h W = 5 - 2 h V = L W h V = (17-2h)(5-2h)h = (17-h)(5h-2h^2) dV/dh = (17-h)(5 - 4h) +(5h-2h^2)(-1) = 85 - 73 h +4 h^2 -5h + 2 h^2 = 85 - 78 h + 6 h^2 where is that derivative zero? h = [ 78 +/- sqrt (6084-2040) ]/12 h = [ 78 +/- 63.6 ] / 12 h = 11.7 impossible, ...
*June 4, 2014*

**physics**

hey, just like the last one ! PE = (1/2) k x^2 PE = m g h = m g d sin 30 = .5 m g d if d is distance along the ramp
*June 4, 2014*

**Math**

sum of degrees of exterior right turns = 360 (all the way around) 360/5 = 72 so each interior angle is 180 - 72 = 108 and 5*108 = 540
*June 4, 2014*

**physics**

loss of potential energy by ball = m g (1.5 + x) gain of potential energy by spring = (1/2)(150)x^2 so 2.2 * 9.81 *(1.5+x) = 75 x^2 21.6 x + 32.4 = 75 x^2 or 75 x^2 - 21.6 x - 32.4 = 0 x = [21.6 +/-sqrt(467+9720) ]/150 x = [ 21.6 + 101 ] /150 x = .817 meter
*June 4, 2014*

**physics**

F = .15 * 45 a = F/m
*June 4, 2014*

**Physics**

first ball stops in 2.3/2 = 1.15 seconds 0 = Vi - g t Vi = 9.81 (1.15) = 11.3 m/s second ball has same Vi Vi = V sin 42 V = 11.3/sin 32 = 21.3 m/s
*June 4, 2014*

**MATH PLZ HELP**

one every 15 minutes is 4 per hour
*June 4, 2014*

**Physics**

0 = 0 + Vi t - 4.9 t^2 Vi = 9.95 sin 35 = 5.71 so 0 = 5.71 t - 4.9 t^2 t = 0 or t = 1.16 t = 0 was zero height when it started t = 1.16 seconds is zero height when it landed
*June 4, 2014*

**Physics**

That is how much negative charge it is missing. (How much positive charge it has)
*June 4, 2014*

**Physics**

F = q E = m a E = m a/q m is given q = 5*10^3 * electron charge a is given
*June 4, 2014*

**Physics**

(2L/3)(3W)(3H)
*June 4, 2014*

**civics**

I do not know. What is the correct C?
*June 4, 2014*

**typo**

You B and C are the same and you left out the right choice.
*June 4, 2014*

**science**

This is oversimplified. Yes, you need data, but you also need a mathematical model and theory.
*June 4, 2014*

**History**

Oligarchy means government by a select few. Therefore I would say B. However it is not necessarily a political party. It could be just a group of rich people or guys with guns.
*June 4, 2014*

**physics**

normal force = 55 g friction force = .11 * 55 g acceleration = F/m = -.11 * 55 * g /55 = -.11 g = -1.08 m/s^2 v = Vi + a t 0 = 5.6 - 1.08 t t = 5.2 seconds to stop go at average speed (5.6 /2) for 5.2 seconds d = 14.5 meters
*June 4, 2014*

**Delcambre High**

(4/15) / (1/3) multiply top and bottom by 15 4 / 5
*June 4, 2014*

**civics**

Mexicans often migrate North to get jobs. Of course Texas and half of California and Arizona and New Mexico ... were Mexico.
*June 4, 2014*

**civics**

Halifax, Quebec, Montreal Ottawa, Toronto --- Vancouver Which are in the North of Canada on the Arctic Ocean ?
*June 4, 2014*

**civics**

It certainly is NOT A !!!! Hey, take a good look at where cities are in Canada Come on, why do Mexicans move North ? Is New York or Chicago or Montreal or Toronto subtropical or tropical ?
*June 4, 2014*

**math**

now wait a minute, time to learn this stuff: In a right triangle: sin theta = opposite / hypotenuse cos theta = adjacent / hypotenuse tan theta = opposite / adjacent so here we have hypotenuse is ladder, 13 adjacent = along ground = 3.7 so cos theta = 3.7/13
*June 4, 2014*

**math**

tan theta = 5.5 / d
*June 4, 2014*

**civics**

By the way, cost on a ship for freight is much less per mile than by any other method.
*June 4, 2014*

**civics**

That would be my answer, but you could disagree if you say why :) I see oceans at the borders, not rivers or lakes for the most part (except the Rio Grande and some Great Lakes of course)
*June 4, 2014*

**civics**

Well, from Halifax to San Diego, North America abounds in seaports on the Atlantic and Pacific although Mexico has relatively small ones.
*June 4, 2014*

**Math**

total length = 20 + 10 = 30 total width = 10 + 10 = 20 so total area = 600 but area of photo itself = 20*10 = 200 so frame area = 400 400/600 * 100 = 67 % is frame
*June 4, 2014*

**chemistry**

PV = n R T = constant so P1 V1 = P2 V2 565 (235) = P2 (215)
*June 4, 2014*

**physics**

We do not know yet if the top block slips. First, assume it does not slip. F = m a 30 = (4+2) a a = 5 m/s^2 Now How much force is required to accelerate the top block at 5 m/s^2? F = 2 (5) = 10 N required How much do we have? Fnormal = m g = 2*9.81 = 19.62 N so friction max...
*June 4, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html here z = (.62 - .60) / .02 = 1
*June 4, 2014*

**Math**

(p q)^3 ( q + p q^2) 3^3 ( q + 3 q) 3^3 (4q) 27 (4 q) 108 q
*June 4, 2014*

**Math**

total marbles = 6 + 10 + 9 = 25 first draw 9/25 second draw 8/24 so (9/25)(1/3) = 9/75
*June 4, 2014*

**science**

v= 3^3 = 27 cm^3 rho = m/v = 54/27 = 2 grams/cubic centimeter
*June 4, 2014*

**Science**

1. b agree 2. a and d, yes, double covalent 3. b, d e yes, but highly radioactive metal 4. d yes 6. yes a, b 8. not sure about 8 but would guess group 1 (b) 9. No, a row is a "period" (b)
*June 4, 2014*

**physics**

dx/dt = b t^2 so x = (1/3) b t^3 + starting x
*June 4, 2014*

**science**

mass of one liter of water = 1 kg Archimedes says: F = m g = 1 kg * 9.81 m/s^2 = 9.81 Newtons
*June 4, 2014*

**Algebra - Steve!! Help!**

By the way, that would be impossible without changing the pressure as well.
*June 4, 2014*

**Algebra - Steve!! Help!**

V T = k *** IF *** I assume this is true then: 500 * 2.5 = k = 1250 so 100 T = 1250 T = 12.5 C I guess that is the answer they want, but in fact V T = constant ONLY if you use degrees KELVIN which is degrees C + 273 so really 500 * 275.5 = k = 137,750 so 100 T = 137,750 T = ...
*June 4, 2014*

**Physics**

Huh ? Are you doing relativity? The force on it is constant, q*E so the acceleration is constant, forever if it were not limited by approaching the speed of light.
*June 3, 2014*

**Physics**

You are welcome.
*June 3, 2014*

**Physics**

Watts is power (Joules/second)
*June 3, 2014*

**physics**

6000 + 2500 = 8500 kg = m m g = weight = 9.81 * 8500 F = weight + m a F = 9.81* 8500 + .5 * 8500 = 87,635 N T = 9.81*2500 + .5 * 2500 = 25,775 N
*June 3, 2014*

**physics**

Ac = v^2/r if you increase v, then v^2 increases by the square of the ratio new Ac = (16/9) old Ac = (16/9)12 = 21.3 m/s^2
*June 3, 2014*

**Physics**

1/R = 1/5 + 2/5 + 1/10 = (2+4+1)/10 = 7/10 so R = (10/7) k Ohms =1.44 k Ohms
*June 3, 2014*

**math 1 question!!!!!!**

- (3/5) a
*June 3, 2014*

**math**

y = m x 9 = m * 5 m = 9/5 so y = (9/5) x or 5 y = 9 x ------------------------- or easier way x/y = 11/1.5 11 y = 1.5 x
*June 3, 2014*

**Physics**

You are welcome.
*June 3, 2014*

**Physics**

V/R = i = 45/15 = 3 amps
*June 3, 2014*

**Math**

combinations of 7 taken 4 at a time C(7,4) = 7! /[ 4!(3!)] = 7*6*5/(3*2) = 35
*June 3, 2014*

**Physics**

T = tension mass 1 = 30/g mass 2 = 20/g for mass 1 m a = m g - T (30/g)a = (30/g) g - T for mass 2 (20/g) a = T - (20/g)g add the two equations (50/g) a = (10/g) g so a = g/5 or about 9.81/5 = 1.96 m/s^2 that is Part B go back and get T for part A then for part C chain tension...
*June 3, 2014*

**Calculus**

2 x^2 + 4 x h = 600 h = (600 -2 x^2 )/4x or h = (300 - x^2)/2x v = x^2 h v = (1/2)( x)(300 -x^2) v = (1/2)(300 x - x^3) dv/dx = (1/2) (300 - 3 x^2) = 0 for max or min so x = 10 then x^2 = 100 h = 10 v x^2h = 1000
*June 3, 2014*

**science**

For electricity: coal, wood, gas, running steam generator , or diesel generator or solar, geothermal, water wheel, wind turbine choice depends on where you are, do you have water power available? geothermal handy? strong winds? Southern exposure to sun?
*June 2, 2014*

**rounding**

Yes
*June 2, 2014*

**Algebra**

4 sqrt 10 - 1 sqrt 10 = 3 sqrt 10
*June 2, 2014*

**Algebra**

well, it is hard for me to graph here so eliminate y by subtracting the second equation from the first x^2 + 5 x -50 = 0 (x-5)(x+10) = 0 so x = 5 or x = -10 if x = 5, then y = -10 if x = -10 then y = 35
*June 2, 2014*

**Algebra**

if -3m = 0, then the whole thing is 0 so if m = 0, the whole thing is 0 if (2m-5) is 0, the whole thing is 0 so if m = 5/2, the whole thing is 0 so the solutions are m = 0 and m = 5/2
*June 2, 2014*

**when the energy of a sound wave is transferred to**

Hey, what do you think the answers are and why ? You can figure it out even if you do not know much physics.
*June 2, 2014*

**math HELP!!!!!!**

You are welcome :)
*June 2, 2014*

**math HELP!!!!!!**

16/40 = x/700 2/5 = x/700 x = 1400/5 = 280
*June 2, 2014*

**physics**

m g h
*June 2, 2014*

**math HELP!!!!!!**

Yes, C
*June 2, 2014*

**math HELP!!!!!!**

no review your text about valid sampling and bias
*June 2, 2014*

**MATH!!!**

V = 156 + 4.5 (t - 12)
*June 2, 2014*

**Algebra**

16 t^2 -20 t - 6 = - h in obsolete English units when does h = 0? t = [ 20 +/- sqrt (400 + 384) ] /32 t = [ 20 +/- 28 ] /32 t = 48/32 = 1.5 seconds (ignore the negative t) for vertex complete the square assuming no calculus may be used 16 t^2 -20 t = - h + 6 t^2 - (5/4) t = -h...
*June 2, 2014*

**Math**

p(f) = 3/20 p(first) = 3/20 = .15 p(second) = 2/19 = .105 p first and second = .15 * .105 = .0158 first fail, second pass = 3/20 * 18/19 first pass second fail = 17/20 * 3/19
*June 2, 2014*

**Physics**

.050 Vo = 1.050 v so v = .0476 Vo initial Ke = (1/2)(.05)Vo^2 final Ke = (1/2)(1.05)v^2 100 (.05 Vo^2 - 1.05 v^2) /.05 Vo^2 100 (.05 Vo^2 - .00238 Vo^2)/.05 Vo^2 = 95.2 % of initial energy is lost
*June 2, 2014*

**Physics**

(1/2)(1200)(900) = 540,000 joules m g h = 1200 * 9.81 * h = 540,000 h = 45.9 meters
*June 2, 2014*

**College Algebra**

x (x-9) =0 x = 0 and x = 9 are correct ps I bet they meant: x^2 - 9 = 0 (x-3)(x+3) = 0 x = 3 or x = -3
*June 2, 2014*

**Math**

arithmetic series see http://www.mathwords.com/a/arithmetic_series.htm here a1 = 30 and d = 4 and n = 10
*June 2, 2014*

**What is the coefficient of x?**

-5
*June 2, 2014*

**Physics**

R = 10 + 8 + 27 i = 9/R for each Vn = i * Rn the sum of Vn better equal 9
*June 2, 2014*

**Math**

a + c = 390 a = 2.25 c so 2.25 c + 1 c = 390, solve for c then for a Revenue = 8 a + 3 c
*June 2, 2014*

**Math**

You are welcome.
*June 1, 2014*

**Math**

tan angle = 34/12
*June 1, 2014*

**science**

When you post a question again and again and no one replies, perhaps there is something missing in the question that renders it incomprehensible. We have no idea where or what you are talking about, on a beach or in a bottle or what else is behind your question.
*June 1, 2014*

**algebra2/ Trigonometry**

24+22+14+12 = 72 marbles yellow = 14/72 = .1944.... or about 19.4 % do the others the same way
*June 1, 2014*

**Geometry**

You are welcome.
*June 1, 2014*

**Geometry**

Volumes scale as the CUBES of corresponding lengths of similar figures (25/35)^3 = (5/7)^3 = 125/343
*June 1, 2014*

**typo**

I have no idea what you mean there are about 6*10^23 anythings per mole just like there are 12 anythings per dozen
*June 1, 2014*

**trigonometry ans.**

You are welcome.
*June 1, 2014*

**trigonometry ans.**

right, you asked for nearest foot
*June 1, 2014*

**trigonometry ans.**

tan 53 = height/distance yes, 66 to nearest foot The right angle is at the foot of the tree. ALWAYS draw a picture tan 53 = opposite (tree) / adjacent(along ground the hypotenuse is along your line of sight, not used here
*June 1, 2014*

**physics**

momentum after momentum before sum of m after v after = sum of m before v before .16 (27.5) + (68) v = 68.16 (2.55) solve for v second skater: (60.5+.16) v = .16(27.5) solve for second skater v
*June 1, 2014*

**Geometry**

ok, always sketch a graph
*June 1, 2014*

**Geometry**

It gets smaller.
*June 1, 2014*

**help**

You are welcome.
*June 1, 2014*

**help**

tan 12 = 40/d d = 40/tan 12 = 188 meters ! If that diver is wearing a hard hat, he is going to be a wreck himself by the time he gets there and it will take so long that he will need to make decompression stops upon ascent to avoid getting the bends. Move the stupid ship !
*June 1, 2014*

**Geometry**

You are welcome.
*June 1, 2014*

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