Tuesday

September 16, 2014

September 16, 2014

Total # Posts: 18,489

**MATH 12**

4 s h + s^2 = 12 so h = (12-s^2)/4s v = s^2 h v = s^2 (12-s^2)/4s = (12 s^2 -s^4)/4s v = 3 s -(1/4) s^3 dv/ds = 0 for max = 3 - (3/4) s^2 (3/4) s^2 = 3 s^2 = 4 s = 2 h = (12 - 4)/8 = 1
*April 28, 2014*

**physics**

V = 60 volts d = .03 meters E = 60/.03 = 2000
*April 28, 2014*

**physics**

no I do not know what question 4 is but divide the voltage by .03 meters to get E in a capacitor E = volts/ distance
*April 28, 2014*

**physics**

d = .03 meters E = V/d
*April 28, 2014*

**physics**

voltage is potential energy per unit charge. because The force on a charged particle in an electric field is q E between the plates of your capacitor E= V/d so the work done on the charge = Force * distance = q E d = = q V so 5*10^-4*60 = 300 *10^-4 = 3*10^-2 or .03J
*April 28, 2014*

**physics**

.1 Joules = 2*10^-6 V V = .1 * 10^6 /2 = .05*10^6 = 5*10^4 = 50,000 volts Yes :) and yes, volts is Joules per coulomb
*April 28, 2014*

**physics**

same thing again and again Volts is potential energy PER UNIT charge That is why they call Volts electric potential change in potential energy = charge * volts !!!
*April 28, 2014*

**physics**

Hey, this is the first problem I did for you backwards.
*April 28, 2014*

**physics**

Yes !!! :)
*April 28, 2014*

**physics**

Amanda, all your questions are answered by Voltage = potential energy per unit charge
*April 28, 2014*

**physics**

E q = Force (Newtons) { like m g ) so E q d = work (Joules) = increase in potential energy (like m g h) so E d = increase in potential energy per unit charge which we call V, voltage or electric potential (per Coulomb implied). like g h (increase in potential energy per unit ...
*April 28, 2014*

**physics**

Yes, m g h is joules in gravitational acceleration g E q = Force (Newtons) so E q d = work (Joules) = increase in potential energy so E d = increase in potential energy per unit charge which we call V, voltage or electric potential (per Coulomb implied).
*April 28, 2014*

**physics**

That is 30 Joules
*April 28, 2014*

**TYPO 60 not 90**

Yes, 60 volts * .5 coulombs = change in potential energy
*April 28, 2014*

**physics**

Yes, 90 volts * .5 coulombs = change in potential energy
*April 28, 2014*

**physics**

I am going to scream! Voltage = change in potential per unit charge. change in potential energy = q * change in V
*April 28, 2014*

**Help- Math**

You are welcome.
*April 28, 2014*

**Help- Math**

F = k/d^2 b) undefined because zero denominator (gets very big as d gets small) c) If an object has mass, it also has size. It is impossible to get d = 0 because the objects bump before their centers of gravity collide. So, although the force can become large, it does not ...
*April 28, 2014*

**Math-Help**

max profit is at 250 so if spending more than that, spend less
*April 28, 2014*

**Math-Help**

5000 = 1+ 50 a -.1 a^2 .1 a^2 - 50 a - 1 = -5000 .1 a^2 - 50 a + 4999 = 0 solve quadratic roots are 250+/-3sqrt1390 250 +/- 112 so 362 or 138
*April 28, 2014*

**Math-Help**

a) where is the vertex? .1 a^2 - 50 a -1 = -p a^2 -500 a -10 = -10 p a^2 - 500 a = -10 p + 10 a^2 - 500 a + 250^2 = -10 p + 62510 (a-250)^2 = -10 (p-6251 so max profit of 6251 at a = 250
*April 28, 2014*

**Math-Help**

No one, like no one, uses feet any more for physics problems but anyway It is a parabola (uppside down, sheds water) c) at t = 0, h = 5,1 d) find the vertex by completing the square or know that the rock is at the top when the velocity is zero which is when -32 t + 100.4 = 0 t...
*April 28, 2014*

**Science**

I is Iodine Cl is Chlorine
*April 28, 2014*

**math**

(1 dollar/16 oz)(40 oz/can)(18 cans) = $45
*April 28, 2014*

**Science**

NH4 +1 and Cl -1 and Na1+1 and OH1-1 are all ions
*April 28, 2014*

**physics**

.45 WHAT? millimeters, meters? pounds ? m/s^2 ? Newtons? Moreover, what is the question? Did you make it up or copy it incorrectly from somewhere?
*April 28, 2014*

**physics**

vetical speed = sqrt (2 g h) = sqrt (232) =15.2 m/s speed = sqrt (15.2^2 + 5.3^2)
*April 28, 2014*

**Math**

7! = 5040 if the two oldest are one, then we only really have six 6! = 720 but one could be right and the other left or reverse so twice that many *2 = 1440
*April 28, 2014*

**biology**

First, the vegetation takes in CO2 and uses it through photosynthesis to make vegetation and release O2. It also prevents runoff of the soil in gigantic floods by absorbing rainfall, protects all sorts of wildlife and flora that does not exist elsewhere, and grows many useful ...
*April 28, 2014*

**biology**

Oh my heavens, best Google that
*April 28, 2014*

**biology**

One might send the residents free firewood or solar panels and stop drinking coffee and stop the out of control growth of the human population.
*April 28, 2014*

**math**

(3b+2) / (9b+6) = 1(3b+2)/3*(3b+2) = 1/3 so the length is one third of the width :)
*April 28, 2014*

**biology**

More CO2 and less O2 in atmosphere (greenhouse effect) Loss of biodiversity (species go extinct even before we even knew their blood cured cancer or whatever.)
*April 28, 2014*

**Algebra 2**

twelve draw tree branches or do 3*2*2
*April 28, 2014*

**algebra2**

She gets four raises 30,000 (1 +1.02 +1.02^2 +1.02^3+1.02^4) You could just calculate that out or do it as a geometric sequence.
*April 28, 2014*

**Physics**

r = .039875*10^6 +1.74*10^6 = 1.78*10^6 G = 6.67*10^-11 M = 7.35*10^22 F = m v^2/r G M m /r^2 = m v^2/r v^2 = G M /r T^2 = (2pi)^2 * r^2/v^2 T^2 = (2pi)^2 * r^3 /GM T^2 = 39.5*5.64*10^18/(6.67*10^-11*7.35*10^22) T^2 = 4.54 * 10^7 = 45.4 * 10^6 T = 6.74 * 10^3 = 6740 seconds (...
*April 28, 2014*

**Physics**

Take a good look at the one I just did for help please. The numbers are different but the problem uses the same logic, primarily: T^2 = (2pi)^2 * r^3 /GM ------------------------------------ r = .039875*10^6 +1.74*10^6 = 1.78*10^6 G = 6.67*10^-11 M = 7.35*10^22 F = m v^2/r G M...
*April 28, 2014*

**Physics MCQ - Quick check**

You are welcome :)
*April 28, 2014*

**Physics MCQ - Quick check**

tan theta = sqrt 3/1 theta = 60 deg = pi/3 right
*April 28, 2014*

**Physics MCQ - Quick check**

A cube of mass 2.0 kg is kept pressed against a vertical wall by applying a horizontal force of 60N. If the coefficient of friction between the cube and the wall is 0.50, the frictional force between the cube and the wall is ? 19.6 N ---------------------------- If the cube is...
*April 28, 2014*

**Physics MCQ - Quick check**

Ac = v^2/R = c = 2 pi R Hey, you need to go faster, not slower ! T = c/v = 2 pi R/v so v^2 = (2 pi R)^2/T^2 v^2/R = {(2pi)^2/R T^2] 3 v^2/R = {(2pi)^2/R T^2] *3 so 3/T^2 = 1/T'^2 3 T'^2 = T^2 T'^2 = T^2/3 T' = T /sqrt 3
*April 28, 2014*

**Engineering Physics**

This is comparable to the position derivatives where: velocity = dx/dt and acceleration = d^2x/dt^2
*April 28, 2014*

**Engineering Physics**

omega = angular VELOCITY = d Theta/ dt alpha = angular ACCELERATION = d^2Theta/dt^2 Therefore b)
*April 28, 2014*

**physics**

I answered this before but the question disappeared Heat out of steam= 20 {2260+4.2(100-T)} Heat into water = 80 (T-20) so 4(T-20) = 2260 + 4.2(100-T) 4 T - 80 = 2260 + 4200 - 4.2 T 8.2 T = 6540 T = 797 which is silly of course What it means is that 80 grams of water at 20 ...
*April 27, 2014*

**math**

first pie cost 6 * 20 = 120 cents second pie cost 8 * 30 = 240 cents it doubled which is an increase of 100 % [ (240 -120)/120 ] * 100 = 100%
*April 27, 2014*

**Algebra 1**

This is Algebra 1 where ?
*April 27, 2014*

**Algebra 1**

1 agree https://hrdag.org/convenience-samples-what-they-are/ 2 agree http://en.wikipedia.org/wiki/Sampling_%28statistics%29#Systematic_sampling
*April 27, 2014*

**Maths**

You need five if you have no typos. Draw it on a piece of paper. to use math: tile area = 1/6*1/6 = 1/36 rectangle area = 1/6 * 5/6 = 5/36 5/36 / 1/36 = 5
*April 27, 2014*

**Maths**

Unless you have a typo (which I suspect), five of them in a row would cover it.
*April 27, 2014*

**Math**

I am taking the easy way out: http://www.cs.virginia.edu/~lat7h/blog/posts/219.html
*April 27, 2014*

**Algebra 1**

If that is Algebra 1, you are at a good school :)
*April 27, 2014*

**Algebra 1**

1 Yes (I had to think for a minute:) 2 Yes 3 Yes
*April 27, 2014*

**algebra**

2+3 = 5 so 2/5 and 3/5 2/5 = 10/25 3/5 = 15/25 check: 10 + 15 = 25 yes 10/15 = 2/3 check :)
*April 27, 2014*

**Disappearing questions now ?????**

There was another question in here that seems to have disappeared but my answer remained ?
*April 27, 2014*

**physics**

Heat out of steam= 20 {2260+4.2(100-T)} Heat into water = 80 (T-20) so 4(T-20) = 2260 + 4.2(100-T) 4 T - 80 = 2260 + 4200 - 4.2 T 8.2 T = 6540 T = 797 which is silly of course What it means is that 80 grams of water at 20 degrees simply can not condense 20 grams of steam. The ...
*April 27, 2014*

**physics**

Yes, it is just the ratio of heat of vaporization to heat of fusion. I get 2260 J/gram / 334 J/gram = 6.77 g
*April 27, 2014*

**Linear algebra**

note first that if a = 1, the first and third rows are identical (infinite number of solutions) then calculate the determinant of the coefficient matrix. Find its zeros. One will be a = 0 Look at second equation when a = 0, x+y = 0 and first equation gives x+y = 0 and third ...
*April 27, 2014*

**math**

9 x^2 - 2 x - 4 = 0 x= [ 2 +/- sqrt (4 + 144 ) ] / 18 x = [ 2 +/- 12.2 ] /18 it says approximate so I will say 12.2 = 12 x = 14/18 or -10/18 or x = .8 or -.6
*April 27, 2014*

**physics**

Hey look, Bob Pursley told you how to do these heat gained/ heat lost problems. You keep posting basically the same problem over and over. You are supposed to learn how to do them. Try. Post your attempts.
*April 27, 2014*

**Physics**

south momentum = 1900 * 13.6 = 25840 east momentum = 3854 * 9.8 = 37769 same after of course mass = 1900+3854 = 5754 south momentum = 5754 Vs = 25840 Vs = 4.49 m/s east momentum = 5754 Ve = 37769 Ve = 6.56 m/s V = sqrt (Vs^2+Ve^2) = 7.95 m/s tan angle E of S = Ve/Vs = 6.56/4....
*April 26, 2014*

**Precalculus**

To be in A intersect B, a number must be both prime and a factor of 36 factors of 36 less than 16: 1 3 4 6 9 12 of those only 1 and 3 are prime unite those with the multiples of 4 which are 4 8 12 and you get 1 3 4 8 12
*April 26, 2014*

**English help**

Are people who are willing to die for their religion also willing to kill for their religion? In fact is there a relationship between being willing to die for something and being willing to kill for it?
*April 26, 2014*

**Math**

I posted two answers below the two you got. n^2 - 9 n + 81/4 = (n-9/2)^2 would be a perfect square n^2 - 6 n + 9 = (n-3)^2 would be a perfect square You can not factor n^2 - 9 n + 9
*April 26, 2014*

**Physics**

B) 45 revs/ min * 2 pi radians/rev * 1 min/60 s) = omega final = 4.71 rad/s A) omega = alpha t 4.71 = alpha (85) alpha = ang acceleration = .0554 radians/s^2 so omega = .0554 t
*April 26, 2014*

**MATH**

a^2-b^2 = (a-b)(a+b) y^2 - 25(x-1) unfortunately (x-1) is not a square of anything but (x-1)^.5 :) I suppose you could say [ y - 5 sqrt(x-1) ] [y + 5 sqrt(x-1) ] but that is really stretching it
*April 26, 2014*

**Math**

Now we could try completing the square n^2 - 9 n + 9 = y n^2 - 9 n = y -9 n^2 - 9 n + (9/2)^2 = y - 9 + 81/4 so n^2 - 9 n + 81/4 is a perfect square :) (n-9/2)(n-9/2)
*April 26, 2014*

**Math**

(n-3)(n-3) = n^2 -6 n + 9 unfortunately that 6 is not a 9
*April 26, 2014*

**Math**

You are welcome :)
*April 26, 2014*

**Math**

12/28 = 3/7 n^2/n^4 = n^-2 m^4/m^3 = m^1 = m so 3 n^-2 m or 3 m ----- n^2
*April 26, 2014*

**Trig**

(x - x1) (x - x2) = 0 (x - 5 - isqrt2) (x -5 +isqrt2) =0 distributive property multiply x (x -5 +isqrt2) = x^2 -5 x + ix sqrt 2 -5 (x -5 +isqrt2)= -5 x +25 -5isqrt 2 -isqrt2(x -5 +isqrt2)=-xisqrt2+5isqrt2 +2 add = x^2 -10 x +27
*April 26, 2014*

**Trig**

You are welcome.
*April 26, 2014*

**Trig**

cos = 1/sec = 4/5 cos is positive in Quadrant 4, x is positive and hypotenuse is positive.
*April 26, 2014*

**Math**

Well, you really did not ask a question. All you did was give the equation fort a parabola. So what? y = x^2 - 2 x - 3 do you want to know where that is zero? Where the vertex is? how it looks? if you want the two zeros, just factor it y = (x-3)(x+1) that is zero when: x = 3 ...
*April 26, 2014*

**Science**

sometimes twin stars hold each other in orbit. Imagine the huge gravitational force !
*April 26, 2014*

**Science**

5 is D, close stars. Gravity force between stars is huge despite distance F = G M2 M2 / d^2 between A and B it would be A because same mass but closer (smaller d^2) 7 is B Train around bend is change in DIRECTION. velocity is vector, speed and DIRECTION 8 is A, size is not ...
*April 26, 2014*

**Science**

Oh ok I will check
*April 26, 2014*

**Science**

Hey, I already passed the course. You try to answer the questions and one of us might check and figure out what you are missing. We are not here to take the course for you.
*April 26, 2014*

**physics**

force = pressure * area weight of 10 kg = 9.81*10 = 98.1 N weight of man = maybe 100kg*9.81 = 981 N 981 /50A = pressure force up on other end = pressure * A = 981/50 = 19.62 Newtons well he needs about 100 N and his whole weight only produces about 20 N even though he is a 220...
*April 26, 2014*

**Science**

W*50 + 25*5 + 10*75 = (W+25+10)40 10 W = 525 W = 52.5 gf whatever a gf is :)
*April 26, 2014*

**statistics**

Binomial distribution P = 4420/13168 = .33566 1-p = .66434 P(0) = c(5,0) p^0 (1-p)^5 = 1 * 1 * .66434^5 = .129 P(1) = c(5,1)p^1 (1-p)^4 = 5 *.33566 * .66434^4 = .3269123 P(2) = c(5,2)p^2(1-p)^3 = 10 *.33566^2 * .66434^3 = .330347 sum = .657 P(5) = .66434^5 = .12941
*April 26, 2014*

**Math**

You are welcome :)
*April 26, 2014*

**Math**

ends 2 * 2.5 * 4 = sides 2 * 6 * 4 = bottom 6*2.5 = multiply and add
*April 26, 2014*

**h school**

snow
*April 26, 2014*

**h school**

beaver hides
*April 26, 2014*

**h school**

shale oil ?
*April 26, 2014*

**Math**

-1 -8 +12 | 1 0 +3 24 -36 | 0 1 +1 +8 -12 |-1 0 +3 24 -36 |+0 1 +1 +8 -12 |-1 0 +1 +8 -12 |+0 1/3 HEY, as we should have seen immediately, the second equation is a multiple of the first. THERE IS NO SOLUTION!!! They are the same line on a graph, no intersection. I think it was...
*April 26, 2014*

**physics**

Unfortunately I do not see the drawing.
*April 26, 2014*

**physics**

The sum of the externally applied forces must be zero, and the sum of the externally applied torques must be zero.
*April 26, 2014*

**Calculus Please Help2**

let z = x^6-2 then dz = 6 x^5 dx I think you can take it from there :)
*April 25, 2014*

**physics**

Great !
*April 25, 2014*

**physics**

using your figures g moon = F/m = G M/r^2 = 6.67^10^-11*7.35*10^22 /3.03*10*12 =16.17*10^-1 = 1.67 m/s^2 I guessed 9.8/6 = 1.63 so I would be a little off
*April 25, 2014*

**physics**

Your way I get (1/2)(21/25) vi^2 = G M [1/R - 1/(R+h) ] 21/50 (1210)^2 = 6.67*10^-11 * 7.35*10^22 [ 1/1.74*10^6 - 1/(1.74*10^6+h) ] .615*10^6=49*10^11 (.575*10-6 - z) where z = 1/(1.74*10^6+h) .1255*10^-6 = .575*10^-6 - z z = .449*10^-6 1/z = 2.22*10^6 = 1.74 *10^6 + h h = ....
*April 25, 2014*

**physics**

well, what did you calculate for g moon? If it is not something like 9.81/6 it is wrong, but the 1/6 of earth gravity is a rough approximation.
*April 25, 2014*

**physics**

Oh well, as a first guess since you did not say I will assume g moon = g earth/6 = 9.8/6 = 1.63 m/s^2 so a = -1.6 v = Vi - 1.6 t (2/5)(1210) = 1210 - 1.6 t 1.6 t = 1210 (3/5) t = 454 seconds h = Vi t - ((1/2)(1.6) t^2 = 384,447 meters
*April 25, 2014*

**Algebra**

No problem. You are welcome :)
*April 25, 2014*

**Algebra**

Like I said before when I had to guess what the question was :)
*April 25, 2014*

**Algebra**

if x = 5, the denominator is zero and the function is undefined and x = 5 is excluded from the domain.
*April 25, 2014*

**Physics**

From an ancient reply: fr = fs[(v-vd)/(v-vs)] fs is the frequency of the source, relative to the medium carrying the waves. We assume that is also the speed with respect to the ground (no wind) fr is the received frequency. v is the speed of sound in the air. vd is the speed ...
*April 25, 2014*

**calculus help**

LOL - I do not even remember doing that !
*April 25, 2014*

**calculus help**

vol = pi r^2 h so h = V/(pi r^2) area = pi r^2 + 2 pi r h area = A = pi r^2 + 2 pi r V/(pi r^2) A = pi r^2 + 2 V /r dA/dr = 0 = 2 pi r -2 V /r^2 V / r^2 = pi r V = pi r^3 but V = h (pi r^2) so h (pi r^2) = pi r^3 h = r or h = D/2
*April 25, 2014*

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