Monday

July 28, 2014

July 28, 2014

Total # Posts: 17,552

**geometry**

tan theta = 17/29 Hey, draw a sketch for these problems so you can see what is opposite, what is adjacent and what is hypotenuse.

**physics**

power = voltage * current = 220 * .45 Watts by the way even at 220 volts, .45 amps does not sound like much to cook pizza.

**geometry**

sin 34 = d/180 d = 180 sin 34 = 100.6 ft

**physics**

output = work done = 530 * 4 = 2120 Joules by the way input = 200 * 15 = 3000 Joules

**physics**

luckily 6*10^5 is much less than light speed of 3*10^8 so not a relativity problem v = Vi + a t 5.94 * 10^5 = 2.95*10^5 + 2.7*10^14 t divide by 10^5 5.94 = 2.95 + 2.7*10^9 t 2.7 * 10^9 t = 2.99 t = 1.107 * 10^-9 seconds

**MATH HW HELP!!**

db/dt = .16 b db/b = .16 dt ln b = .16 t + c e^ln b = b = e^(.16 t +c) = C e^.16 t or more simply b = C e^.16 t when t =0 , e^.16 t = 1 so C = value when t = 0 b = 5 e^(.16*12) b = 34.1 grams

**physics**

m g h = work done to lift = 4*9.81*2.5 = 98.1 Joules

**Physics**

2.7 g/mL * 385 mL

**MATH HW HELP!!**

1.08^18 = 4 so $40,000

**AP chemistry**

the Al heats up the water cools down 25 * .897 * (40-0) = 100 * 4.186 * (Ti-40)

**math**

C = P + 32 M = 4 P - 38 C + P + M = 828 P + 32 + P + 4 P - 38 = 828 6 P -6 = 828 6 P = 834 P = 139 now go back and get C and M

**MATH HW HELP!!**

well, I can do it using daily but I bet continuous compounding will give the same answer to the nearest dollar :) anyway daily interest = .01825/365 = 5 * 10^-5 number of periods = 365 * 4 = 1460 1 + 5*10^-5 = 1.00005 1.00005^1460 = 1.07573 note this multiplier 1.07573 x = 25,...

**math**

You are welcome :)

**math**

d = 4/3 p d + p = 21 or 56 or whatever so (4/3) p + (3/3) p = 21 or 56 or whatever so (7/3) p = 21 or 56 p = (3/7) of whatever and d = 4/3 of that

**MATH HW HELP!!**

12/4 = 3% per period 7* 4 = 28 periods 1.03^28 = 2.288 so 2.288 x = 25,000 x = 10,927

**Chemistry**

You are welcome :)

**Chemistry**

Just look at the units: Joules = Joules/gram deg C * grams * deg C grams cancel deg C cancels left with Joules = .897 * 200 * 10 Joules = 1794 Joules

**math homework help**

r = .045/12 = .00375 number of periods = 12 *3.5 = 42 months 1.00375^42 = 1.170235983 times 250000 = 292,558

**Calculus**

Not necessarily for example if the data lies along a straight line the slope is the same everywhere You have to take a straight edge and try to make it tangent to your graphed curve at the origin. I do not know what your data looks like so can not say.

**Physics**

the period is 2 pi * square root of L/g we know the length however to find the period we need g on the surface of earth g is about 9.81 m/s^3 HOWEVER on the moon for example is is only about one sixth of that so the period will be sqrt 6 longer IN OTHER WORDS WE MUST KNOW g on...

**Science**

F = m a so a = F/m same F, m' = m/2 F = (m')a' a' = F/m' = F/(m/2) = 2 F/m = 2 a

**Physics**

I do not know but I can tell you the MAXIMUM efficiency which is that of a Carnot cycle High temp = 680 + 273 = 953 Kelvin Low Temp = 220 + 273 = 493 Kelvin Carnot efficiency = 100*(hot-cold)/hot = 100 (953-493)/953 = 48.3 %

**Science**

force down = m g - drag so m g-drag = m a where a is acceleration down a = g - drag/m so at the beginning, with low drag, the acceleration down is about 9.8 m/s^2 as the drag increases, the a goes down until terminal velocity is reached. That is when m g = drag when you open t...

**Science**

If the car was moving at 50 mph then you were moving at 50 mph. If the car de-accelerates to a stop suddenly and there is no back force on you, you continue to move at 50 mph (first law) Now the car is stopped and you are moving at 50 mph toward the windshield. It would be bet...

**Physics**

w = omega = 16.3revs/min * 2 pi rad/rev *(1 min/60 s) = 1.71 radians/s v = omega r = 1.71 * 10 = 17.1 m/s Ac = v^2/r = 29.1 m/s^2 29.1/9.81 = 2.97 gs F = m a = 70 * 2.97 = 208 Newtons toward center There is no angular acceleration so no torque as far as I know.

**algebra**

OJ .5(8) + x = 2+x Total 8 + x so 2+x = .4(8+x) 2 + x = 3.2 + .4 x .6 x = 1.2 x = 2

**math**

(0,0) (2,0) (4,3) (2,3) well, you could cut it out of cardboard :) It goes to quadrant 2 The top face becomes the left face, so it faces a different way so d If you spin 90 deg left from quadrant 1, how could you be in quadrant 4 ?

**algebra**

If you did include them all (I wonder how many government candidates liked the program?) then .25 * 360 = 90 degrees

**algebra**

what on earth do the students who run for government have to do with this? Leave them out, part of another survey. We asked 230 students about this program evidently 110 of them liked it so (110/230)(360 degrees) = 172 degrees

**math**

for n = 5 coefs are 1 5 10 10 5 1 for example C(5,3) = 5!/[ 3!(5-3)!] = 5*4/2 = 10 so 1 x^5 + 5 x^4(-3) +10 x^3(-3)^2 +10x^2(-3)^3 +5x(-3)^4 +1 (-3)^5 = x^5 -15x^4+90x^3-270x^2+405x-243

**Asap please????**

I am not sure they could be counted there were so many local laws.

**algebra!!!**

I already did this tonight (x+1)(x-1) = x^2-1 = 40 x = sqrt 41 = 6.4

**Algebra**

12 a /(a^2 -3 a -10) if the denominator is zero, that is undefined and out of the domain so all we want to know is for what a is the denominator zero. It does not matter what the numerator is a^2 -3 a -10 = 0 a = [ 3 +/- sqrt (9 +40) ]/2 a = 10/2 or -4/2 so a = 5 or -2 are EXC...

**math**

You are welcome :)

**math**

Yes, A a REGULAR pentagon has rotational symmetry, but only if REGULAR

**Math**

The mode for the first one is 100 The mode for the second one is 95 first one ranges from 85 to 100 second one ranges from 81 to 100 mean of first is 94 mean of second is 94 remarkable ! median of first is 90 median of second is 95

**math**

takes too long calculate mean, the sum/10 calculate (x-mean)^2 for each x add them divide by 10 take the square root

**math**

(4/15)^2 = 16/225

**math**

4+3+5+2 = 14 two independent 4/14 draws (2/7)^2 = 4/49 = .0816

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

You are welcome :)

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

Of course if we had sketched a graph, we would have seen a straight line and not have bothered with the parabola :)

**MATH 1 QUESTION VERY HARD PLS HELP ASAP!!!!!**

well, try a parabola since we have three points y = a x^2 + b x + c 1 = a (4) + b (2) + c 0 = a (16 ) + b(4) + c -1 = a(36) + b(6) + c subtract second from first 1 = -12 a -2 b subtract third from second 1 = -20 a -2 b subtract 0 = 8 a a = 0, this is a straight line 1 = -2 b b...

**fdr**

x by y x y = 100 23 x + 10 x + 20 y = cost = c 33 x + 20 y = c y = 100/x so 33x + 2000/x = c dc/dx = 0 for min = 33 -2000/x^2 33 x^2 = 2000 x^2 = 60.6 x = 7.785 ft y = 12.845 ft

**algebra**

(x+1)(x-1) = 30 x^2 = 31 x = 5.6

**math**

Yes, A is correct :)

**math**

Oh, sorry Jake, misunderstood your reply

**math**

Jake, your answer is A -5 --->+5

**math**

sketch it on a graph !!! Hint, straight back :) (-3,5)

**MATH**

if you rotate it 60 degrees (360/3), it looks exactly like it did before since there is a corner at every 60 degrees your answer to the second part is correct. Unlike circles, you can cover your flat roof with them with no leaks. http://mathforum.org/sum95/suzanne/whattess.html

**math**

first what is QR which is p? law of cosines p^2 = q^2 + r^2 - 2 p q cos P p^2 = 9.6^2 + 7.4^2 - 2(7.4)(9.6)cos 53 solve for p then law of sines sin R/7.4 = sin 53/ p

**algebra**

y = -3 + cos 2 pi (3/2pi) x or y = -3 + cos 3 x

**algebra 2**

7^(1/5) = fifth root of 7

**Science**

It did not result. The force caused the acceleration ! F = m a F = 3000*20 = 60,000 N

**Algebra**

total females = 80+80+70 = 230 80 of those in humanities first 80/230 = .348

**algebra**

1/sin (7pi/6) 7 pi/6 is pi/6 or 30 degrees below -y axis in quadrant 3 so sin 7 pi/6 = -1/2 inverse is csc = -2

**math**

sketch it in quadrant 2 y = 1 x = -1 tan theta = y/x = -1

**geometry**

1 meter by 0.2 meter boards? area board = .2 m^2 area floor = 50 m^2 50/.2 = 500/2 = 250

**Math**

when does 4 x = 2 pi , a full circle ? x = 2 pi/4 = pi/2 the single amplitude is given, 3

**Algebra**

d^2 = (y2-y1)^2 + (x2-x1)^2 d^2 = 5^2 + 12^2 = 13^2 (5 12 13 right triangle) 13

**math help**

x = -7717/335 y = -36738/335 z= 16662/335

**typo?**

-3 ??? x ???? +13y+29z=81 and what do you want? A solution using Gauss Jordan ? If so go to: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

**algebra 1**

multiply both sides by -1 This changes the direction of the arrow 2 x/7 + 8 < 9 2 x/7 < 1 2 x < 7 x < 3.5

**math help**

Just told you, 4/5

**math help**

sin R = 3/5 = r/s t^2 = 5^2 - 3^2 = 25 - 9 = 16 so t = 4 tan T = t/s = 4/5

**Algebra 2**

ten scores in order: 81 81 82 84 85 86 89 93 94 95 sum = 870 mean = 870/10 = 87 median 85.5 (5 above, 5 under) mode = 81 (there are two of them)

**algebra1**

LOL - Yes, I suppose.

**algebra1**

******** -6 x^2 + 4 x + 3 ********____________________________ (3x+2) | -18 x^3 + 0 x^2 + 17 x + 6 *********-18 x^3 -12 x^2 *****************12 x^2 + 17 x + 6 *****************12 x^2 + 8 x *************************9 x + 6 *************************9 x + 6 remainder = 0 ========...

**Algebra 2**

area bulls eye = pi (6^2) total area = pi (16)^2 6^2/16^2 = 2^2*3^2 /2^8 = 9/2^6 = 9/64 = .140625

**Algebra/can you explain how this is set up**

150 * 150 * 150 ------ P1 times or log x = P1 log 150 using for example ten base then x = 10^log x

**Math help**

1, 2, 3, 4, 5, 6 p greater than 2 = 4/6 = 2/3 p 2 or smaller and prime = 2/6 = 1/3 2/3 + 1/3 = 1 every single side of the cube is either greater than 2 or prime (two and one) so you simply will get the desired result in 100% of your rolls :)

**Algebra**

combinations of 10 three at a time = 10!/ [ 3! (10-3)! ] = 10 * 9 * 8 *7* .......1 /[3*2(7*....1) ] = 10 * 3 * 4 = 120 or look up binary coefficient (10,3) = 120 or look at Pascal's triangle row 10, element 3 (the eleventh row, fourth element really since zero counts) agai...

**Science**

Note from wikioedia: Uranium-238 - Wikipedia, the free encyclopedia en.wikipedia.org/wiki/Uranium-238 Wikipedia Jump to Radioactivity and decay - [edit]. 238U radiates alpha-particles and decays **** (by way of thorium-234 ****** and protactinium-234) into uranium-234. 234U ...

**Science**

U238 for example has 92 protons and therefore 146 neutrons It loses an alpha particle which is a helium nucleus, 2 protons and 2 neutrons so NOW we have an element with 92 - 2 = 90 protons 238 - 4 = 234 atomic mass ignoring E = mc^2 What has 90 protons? Th Thorium 232 is usual...

**math**

33/77 , 21/77 , 7/11 Now which is big and which is small ?

**Social Studies**

Gee, remarkable. You are welcome :)

**Social Studies**

1 yes 2 yes 3 yes !!! 4 yes 5 I think d because of shape of Mexico city valley between mountains 6 yes 7 yes 8 yes 9 yes

**Algebra 2**

I still do not have any idea what the question is.

**Algebra 2**

| 3 2 5 | |B11 B12 B13| |5| | 2 -1 8|+|B21 B22 B23|=|0| | 4 7 -3| |B31 B32 B33| |3| Is that what you mean ??? or what ?

**Algebra 2**

Are they matrices? is A square and C a column?

**Algebra 2**

Sorry, I don't get it. Is A a square matrix and B and C columns or what? do you mean A * B or A + B ???

**Algebra 2**

|+3 +2 -5 | |x| |20| |+5 -10 8 |*|y|=|17| |-8 +11 -2| |z| |29| to solve: http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

**CHEMISTRY**

22.4 liters/mole for perfect gas at STP C + O2 --> CO2 46 g of C which is 12 grams/mole so we need 46/12 = 3.83 moles of carbon and 3.83 moles of O2 3.83 * 22.4 = 86 liters

**Math Help? Check my answers.**

4. Write the expression using a single exponent. 2^2 • 2^8 Oh my ! a^x * a^y = a^(x+y) !!!!! 2^2 * 2^8 = 2^(2+8) which is 2^10

**Math Help? Check my answers.**

3. ***** -7x***** - 5x^2 + 5, what is the coefficient of x -7x so -7 is coef of x !!!

**Math Help? Check my answers.**

2. 6x^4 + 3x^3 - 2x^2 + 15x - 14 one ,,, two,,,three,,four, five

**Math Help? Check my answers.**

2. disagree 3. disagree 4. disagree 5. disagree sort of. A works but 10*10^7 is usually written 1 * 10^8 which is C

**Algebra 2**

For heavens sake look up the definition of these terms instead of guessing !!!

**Physics**

b) w = 2 pi/T = sqrt (k/m) (2 pi)^2 /T^2 = k/m k = 2 (2 pi)^2/ 1.8^2 = 24.4 n/m (I do not know how you got the same answer) !!!! c) when it is stopped at x = .08 meters, all the energy is potential (1/2) k x^2 (1/2)(24.4) (.08)^2 = .0781 Joules d) Ke = .0781 Joules = (1/2)mv^2...

**algebra/have no idea how to do this one**

That is what I did Mary Ann I use r = interest rate/number of payments in a year so your n t is my n and your r/n is my r and my n is 40 *12, your n t

**algebra/have no idea how to do this one**

are we doing amount of an annuity here? here? If so: A = payment [ (1+r)^n -1 ]/r r is interest PER PERIOD = .08/12 = .006667 n is number of periods = 40*12 = 480 months payment = 150 A = 150 [1.006667^480 -1 ] / .006667 A = 150(23.27339)/.006667 A = $ 523,624.99

**math**

Try tessellating a circle.

**Calculus**

Ah hah, a real calculus problem :) dV/dt = - k V dV/V = -k dt ln V = -k t + C e^ln V = V = e^(-kt+C) = c e^-kt so here at t = 0 e^0 = 1 so V = c = 70,000 and V = 70,000 e^-kt now when t = 10/12 years, V = 22,222 22,222 = 70,000 e^-k(.83333) ln (22,222/70,000) = - .83333 k -1.1...

**Calc**

total lift if you release water to the atmosphere .5 meter up at the pump = .5 + .75 meters = 1.25 meters total mass = 1000kg/m^3 * 50*25*1.5 = 1.875 *10^6 kg total weight = m g = 9.81*1.875*10^6 = 1.84*10^7 Newtons total work done = weight * distance = 1.84*10^7 *1.25 = 2.23 ...

**Calc**

The same. You have to lift the center of mass of the water up to the pump either way. Of course if you attach a tight hose to the outlet you save lifting a half meter by releasing the water at ground level rather than .5 meter up.

**Calculus**

See the reply to the question above this one from "Jen". Find the mass and m*g, the center of mass, and how far you lift the center of mass. In all these questions if you lower the outlet with a tight outlet hose you can siphon the water out without doing any work at...

**Calculus**

In your earlier question you did not "factor out" the log function. you (or Reiny) said if log x = log y then x = y

**Calculus**

Not calculus. algebra .08/4 = .02 per quarter n = number of quarter years 15825 = 4500 (1.02)^n log (15825/4500) = n log 1.02 .546131 = n log 1.02 n = 63.5 quarter years so 63.5 /4 = 15.88

**Need help with pre cal hw**

LOL, physicist / mathematician again.

**Need help with pre cal hw**

note 160 = south - 20 North distance = 8 cos 30 - 6 cos 20 East distance = 8 sin 20 + 6 sin 20 distance = sqrt (North^2 + east^2) 2. call it 132 = south - 48 north distance=-61.1cos 48 +76.5sin 36.5 east distance =61.1sin48 +76.5cos 36.5 tan theta = north/east

**Physics**

How far does it go in 30 seconds (1/2 minute)? (1/2)min * 1 hr/60 min *120,000 m/hr = 1000 meters 360/20 = 18 the circumference of the turn = 18,000 meters 2 pi r = 18,000 r = 2865 meters Ac = v^2/r = (120,000/3600)^2 / 2865 = .388 m/s Check my arithmetic !! usually plane bank...

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