Sunday

September 21, 2014

September 21, 2014

Total # Posts: 18,581

**science**

I have no idea. There are two naturally occurring isotopes of silver, 107 and 109, but that is not enough difference.
*August 23, 2014*

**Algebra**

If you meant to type (3/5)^3 then you are right.
*August 23, 2014*

**math**

pi r^2 - 9 4 pi - 9 about 3.566370614
*August 22, 2014*

**I have a pretty hard one**

5600/27 is a common fraction
*August 22, 2014*

**I have a pretty hard one**

there is a trick to finding the fraction for a repeating decimal by the way. Google repeating decimal in this case for example .407407407 ---- 1000 x = 407.407407407..... x = .407407407.... so 999x = 407 x = 407/999 = 11/27
*August 22, 2014*

**I have a pretty hard one**

oh 70 / (45/100 *75/100) 70 * 100 *100 / (45 * 75) 14 * 20 * 100 / (9 * 15) 14 * 4 * 100 / (9 * 3) 5600 / 27 = 207 11/27 because 207 * 27 = 5589 and 5600 - 5589 = 11
*August 22, 2014*

**I have a pretty hard one**

.45 * .75 * n = 70 n = 70/ (.45*.75) n = 70 / .3375
*August 22, 2014*

**math**

.24 n = 45 so n = 45/.24
*August 22, 2014*

**Physical science**

http://dwb4.unl.edu/Chem/CHEM869R/CHEM869RLinks/www.nidlink.com/7Ejfromm/arrhenius.htm
*August 22, 2014*

**math mental math**

as I said down below 17 - 2 + 2 + 38 = 15 + 40
*August 22, 2014*

**physics**

been there, done that
*August 22, 2014*

**physics**

54 km/h * (1 h/3600 s)*(1000 m/km) = 15 m/s 15 m/s / 5 s = 3 m/s^2 (1/2) m v^2 Joules (1/2) m v^2 Joules/15seconds ---> Watts
*August 22, 2014*

**math**

DRAW A PICTURE The change of an integral at the right hand limit is the area defined by the height , f(x), times dx In other words the answer is f(2sqrt2) 2sqrt [2sqrt 2)^2+1] = 2sqrt(8+1) =2* 3
*August 22, 2014*

**MATH HELP**

17 - 2 + 2 + 38 = 15 + 40
*August 22, 2014*

**MATH HELP**

I would add 15 to 40
*August 22, 2014*

**Related rates math in calculus**

L = 18-2x w = 18-2x h = x V = x(18-2x)^2 dV/dx = 0 for max or min 0 = x (2)(18-2x)(-2) + 1 (18-2x)^2 0 = -4x (18-2x) + 324 - 72 x + 4 x^2 0 = -72 x + 8 x^2 + 324 -72 x + 4 x^2 0 = 12 x^2 - 144 x + 324 0 = x^2 - 12 x + 27 0 = (x-3)(x-9) x = 3 or 9 but 9 will not work (is V=0) ...
*August 22, 2014*

**math**

You are welcome :)
*August 21, 2014*

**math**

100,000 to 999,999 is one hundred thousand to nine hundred and ninety nine thousand nine hundred and ninety nine.
*August 21, 2014*

**Earth Science**

He said .... then .... experimentation supported Amit agrees :)
*August 21, 2014*

**Earth Science**

The scientist SUSPECTED that acid might be harmful. Therefore experiment to see if CO2 in water harms shells
*August 21, 2014*

**math**

32 gal/min * (60 min/ hr) * (4 qt/gal) = 7680 qt/hr notice that I multiply by things that are the same top and bottom but different units 60 min = 1 hr 4 qt = 1 gal I do the numerator and denominator to make the units I want to get rid of cancel and leave the new ones that I ...
*August 21, 2014*

**math - and so on?**

You did not say what he charged per mile after 2 miles
*August 21, 2014*

**life sciences**

http://humanorigins.si.edu/evidence/human-fossils/species/australopithecus-sediba
*August 21, 2014*

**Math**

2 L + 2 w = 12 so L = 6-w area = A = L w L w = (6-w)w = A w^2 - 6 w = -A find vertex by completing square w^2 - 6 w + 9 = -A+9 (w-3) = -1(A-9) max at w = L =3 and area = 9 By the way, you could have guessed that our rectangle would turn out to be a square.
*August 21, 2014*

**Math**

(y-4)/(x-0) = (-1-4)/(1-0) (y-4 ) = -5 x y = -5 x + 4 now sketch a graph of that
*August 21, 2014*

**ALGEBRA**

12 marbles first draw 3/12 = 1/4 second draw 5/11 1/4 * 5/11 = 5/44
*August 21, 2014*

**math**

if p </= 30 , then c = 750 if p >30 then c = 20 (p -30) + 750
*August 21, 2014*

**college algebra**

A 1/12 pool / hr B 1/24 pool / hr together 3/24 pool/hr so 24/3 = 8 hr/pool
*August 20, 2014*

**algebra**

sketch a graph !!! looks like a straight line with slope = -1 to me
*August 20, 2014*

**Math**

two are already decide. You have two more flips. What is the chance of getting one heads and one tails out of those two flips ? You have four possibilities HH HT TH TT two of those four work, TH and HT so I get 1/2
*August 20, 2014*

**physics**

Try using these: https://answers.yahoo.com/question/index?qid=20081123194116AA3FxdL use that for the average speed and standard deviation. Then he range is so narrow I would assume a normal distribution and use that average and standard deviation in the normal table rather ...
*August 20, 2014*

**calc**

A = 2 x (a^2+x^2)^.5 dA/dx = 2 x (2x)(.5)(a^2+x^2)^-.5) + 2 (a^2+x^2)^.5 = 0 for max or min
*August 20, 2014*

**static and dynamics**

force down slope = m g sin 34 so friction force = force down slope if it is not accelerating down slope.
*August 20, 2014*

**math**

z 2 x y z + 2 + x + 7 = 13 z is even or z = 2 w 2w + 2 + x + 7 = 13 2 w + x = 4 x must also be even or 0 x = 0 then w = 1 if x = 2 then w = 1 so if x = 0 then w = 2 2227 4207
*August 20, 2014*

**math**

4915/72 =
*August 20, 2014*

**math**

40 + 20 = 60 60 - 28/7 = 60 - 4 = 56 56 + 30/5 = 56 + 6 = 62 62 - 3 = 59
*August 20, 2014*

**algebra HUH??**

meaningless
*August 20, 2014*

**physics**

Calculate pressure halfway up the wall p = 1000 kg/m^3 * 10 m/s^2 * 2 m thrust on one wall = p * area
*August 20, 2014*

**physics what is side and length of bottom?**

.2 m square or .1 m square on bottom? I will assume bottom square size s and depth h pressure = density * g * h if h is .5 m (it is not clear what depth of alcohol is from sloppy wording of question. It is the depth that matters, not how high the container is off the ground.) ...
*August 20, 2014*

**Science**

24 g of Mg is how many mols of Mg ? so How many mols of O ? (Hint: MgO has exactly as many mols of O as of Mg , note of O at 16 g/mol, not O2 at 32 g/mol) so mass of O = mols of O * 16 g/mol
*August 20, 2014*

**Chemistry**

True :)
*August 20, 2014*

**Connexus**

If it were condensed it would be a liquid, not a gas.
*August 20, 2014*

**physics**

F = G Me m/R^2 = approximately m g because G Me/R^2 is pretty much constant around earth surface 1/R^2 Toward the center of mass of the object that is pulling it, for example toward earth center.
*August 20, 2014*

**physics/ basic of statics**

3 kg weighs 3*9.8 = 29.4 Newtons 5 kg weighs 5*9.8 = 49 Newtons say the 49 N force is in the x axis direction tthe 29.4 N force is 60 degrees toward the Y axis Sum of x forces= 49+29.4cos 60 = 63.7 N Sum of y forces = 29.4 sin 60 = 25.5 N magnitude = sqrt(25.5^2 + 63.7^2) = 68...
*August 19, 2014*

**Science**

I take that back, both question can be asked and then hypothesis posed: http://www.sciencebob.com/sciencefair/scientificmethod.php
*August 19, 2014*

**Science**

pretty much, although usually the word "hypothesis" is used instead of question. One tends to pose a hypothesis, then test so see if it works.
*August 19, 2014*

**math**

Remember back when when you were learning addition you had the commutative property of addition which means 2 + 3 is the same as 3 + 2 Now you are getting the same property for multiplication :)
*August 19, 2014*

**math**

you just did. The property means that 8 * 7 is exactly the same as 7 * 8 In other words the two factors commute, you can change their order without changing their product. This will be true until you get to multiplying matrices.
*August 19, 2014*

**math**

P = (60 - 22) x - 75 = 38 x = 75
*August 19, 2014*

**math**

(x+h)^2 + 2 = x^2 + 2 x h + h^2 + 2 the are getting you ready to find the derivative which is the limit as h -->0 of [f(x+h) - f(x) ]/h which here would be limit as h -->0 of (2 x h + h^2)/h or 2 x + h as h -->0 is 2x which is df(x)/dx
*August 19, 2014*

**science**

density is mass per unit volume if the volume of steel is the same and the mass more then the density of the steel is more. (strange by the way)
*August 19, 2014*

**physics**

dv/dt = -1/t^2 v = (1/t) + c 3 = 1 + c c = 2 v = (1/t) + 2 if t = 4 v = 2.25
*August 19, 2014*

**physics**

dv/dt = -kv dv/v = - k dt ln v = - k t + c e^ln v = v = e^(-kt +c) = e^c e^(-kt) when t = 0, v = Vo Vo = e^c e^0 = e^c so v = Vo e^-kt
*August 19, 2014*

**physics**

2 seconds rising and 2 seconds falling h = (1/2)g t^2 falling 10 = (1/2) g (4) = 2 g g = 5 m/s^2
*August 19, 2014*

**physics**

it evidently goes forward a distance 3d then back a distance 2d to end up a displacoutup to be negative. deceleration phase out to 3 d t1 = time out to 3 d v = Vi + a t1 0 = Vi + a t1 so t1 = -Vi/a 3 d = Vi t1 + (1/2) a t1^2 3d = -Vi^2/a + .5 Vi^2/a = -.5Vi^2/a d a = -(1/6) Vi...
*August 19, 2014*

**Language Arts**

I can not see your italics but suspect it is the "ing" and D is correct. http://en.wiktionary.org/wiki/present_participle
*August 19, 2014*

**math**

5 y + 7 x = 31 x y 5 y + 7 x = 29 x y well, (0,0) would work but then we would be dividing by zero in the original.
*August 19, 2014*

**English**

"His questions revealed an intelligence" seems to be the main idea so what is the rest ? http://www.chompchomp.com/terms/relativeclause.htm
*August 19, 2014*

**english**

http://www.merriam-webster.com/dictionary/tally
*August 19, 2014*

**P.E**

I figure my natural crabbiness is likely to be fatal, perhaps even to me.
*August 19, 2014*

**P.E**

Certainly
*August 19, 2014*

**english**

Let me see: He spread the rumor widely. ------> He spread the rumor most widely ?
*August 19, 2014*

**math**

There are six numbers so add them all up and divide the sum by six.
*August 19, 2014*

**Philippine history**

http://www.academia.edu/4833169/Continued_Filipinization_in_the_Late_20th_Century_The_Case_of_the_Ateneo_de_Manila_University_1968-1991
*August 19, 2014*

**Philippine history**

http://prezi.com/cfw8l09tjkas/filipinization-policy/ When the US defeated the Spanish in the Spanish American War, the Philipines ceased to be a Spanish colony and came under the US. The US made an effort to let the indigenous people take over ruling their islands replacing ...
*August 19, 2014*

**Physics**

All I can do is tell you the method. call M1 the mass of the one that is on string at 50 degrees from vertical (aI assume from vertical Then gravity force down slope is M1 g cos 50 T is up slope net force down is (M1 g cos 50 -T) same deal for M2 net force down is (M2 g cos 30...
*August 19, 2014*

**Physics**

I do not understand this geometry. Is the big one trying to drop down a 53 deg slope and the little one being dragged up a 30 degree slope or what?
*August 19, 2014*

**Physics**

The table is three football fields long and three football fields high? I bet it was 0.15 seconds actually :)
*August 19, 2014*

**Physics**

big table :)
*August 19, 2014*

**Physics**

F = 20 * 9.8 m = 50 + 20 = 70 a = F/m = 2.8 m/s^2 force on falling 20 kg mass = 20 (9.8) - T = m a = 20(2.8) so T = 140 Newtons d = (1/2) a t^2 = (1/2) 2.8 (225) = 315 are you sure you did not mean 1.5 seconds?
*August 19, 2014*

**science**

probably at least on a cell scale.
*August 19, 2014*

**Second law of motion**

Net force up = 35 - 25 = 10 Newtons F = m a m = 25/9.8 = 2.55 kg so a = 10 / 2.55 = 3.92 m/s^2
*August 19, 2014*

**Physics**

Good grief, English units, have to put mass in slugs and use seconds and pounds and feet. (Back to freshman year in 1955) change in speed = 40 miles/ hr *5280 feet/mile * 1 hr/3600 seconds = 58.7 feet per second mass in slugs = 3000 lb /32 ft/s^2 = 93.8 slugs F = change in ...
*August 19, 2014*

**Science**

north velocity = 30 (assume west wind so blowing plane east) east velocity = 40 total speed = sqrt (30^2+40^2) = 50 km/hr tan angle east of north = 40/30 angle east of north = 53.1 or about northeast by east (NExE)
*August 19, 2014*

**Physics**

F down slope = m g sin 35 a = F/m = g sin 35 = 9.8 sin 35
*August 19, 2014*

**math**

a + a r + a r^2 + a r^3 + a r^4 ....+a r^(n-1) so a r = 1.5 a r^4 = .1875 a = 1.5/r (1.5/r) r^4 = .1875 r^3 = .125 r = .5 a = 1.5/.5 = 3 so 3 + 1.5 + .75 ......
*August 19, 2014*

**science**

Huh ?
*August 19, 2014*

**Parabola**

axis of symmetry is halfway between 2 and 3 or x =2.5 to get the zeros of y at x = 2 and 3 y = k (x-2)(x-3) to get y = 6 at x = 0 6 = k (-2)(-3) k = 1 so y = x^2 -5 x + 6 (answer) check if vertex is at x = 2.5 by completing the square y -6 = x^2 - 5 x y - 6 + (5/2)^2 = x^2 - 5...
*August 19, 2014*

**Maths**

(1-e^-x) integral (1-e^-y) dy from 1 to 2 (1-e^-x) [ y + e^-y ] at 2 - at 1 (1-e^-x) [ 1 + (e^-2 - e^-1) ] (1-e^-x) [ .767 ] integrate that dx from 1 to 3 [ .767 ][ x + e^-x] at 3 - at 1 [ .767 ] [ 2 + (e^-3 - e^-1) ] [ .767 ] [ 1.68 ] 1.29 divide by area to normalize area = 2...
*August 19, 2014*

**algebra**

I do not dare because I bet you have typos. For example I would be surprised if -1^2 is not supposed to be (-1)^2.
*August 19, 2014*

**physics**

no s = -16 t^2 + 64 t If the ball left the ground with velocity + 64 ft/x then it returns to earth with velocity -64 ft/s. Your parabola is symmetrical and the vertex is at the top,
*August 19, 2014*

**Math**

Sorry, can not email to you. The word compass bearing is used correctly here. tangent of angle north from west axis = 70/145 tan^-1 (70/145) = 26 deg so bearing = 270+26 = 296 degrees clockwise from North this is approximately west north west
*August 18, 2014*

**math**

Henry, The 30 degrees is from North (the y axis), not from east (the x axis as in math convention).
*August 18, 2014*

**math**

^&%#*& mathematicians ! He flies on a HEADING of 030 east of north, NOT a bearing. You take a bearing on something, its direction from you. You sail or fly a compass HEADING. anyway East components are 90 sin 30 +150 =90 * (1/2) + 150 = 45 + 150 = 195 km east of start
*August 18, 2014*

**math**

actually the express train from Delhi to Meerut seems to go about 44 km/hr by the way: http://indiarailinfo.com/search/new-delhi-ndls-to-meerut-cantt-mut/664/0/1546
*August 18, 2014*

**math**

they approach each other at 180 km/h 75 km * (1 h/180 km) = .4167 h * 60 min/h = 25 minutes so 8:25 am
*August 18, 2014*

**social studies**

http://dictionary.reference.com/browse/xenophobia
*August 18, 2014*

**social studies**

Thank you Lexie Bowles. That was fun !
*August 18, 2014*

**social studies**

http://civilliberty.about.com/od/immigrantsrights/tp/Xenophobia-in-United-States.htm
*August 18, 2014*

**social studies**

http://en.wikipedia.org/wiki/Anabasis_%28Xenophon%29
*August 18, 2014*

**math**

50 in 125 and 30 in 90?
*August 18, 2014*

**math**

9 + 63 = 72 using rounding which happens to be exact and I also call 9 and 63 compatible numbers since adding 9 to anything is super easy.
*August 18, 2014*

**physics**

V defined as speed out of the barrel time rising = time falling so find rise time and multiply by 2 vertical problem: Vi = V sin 30 = .5 V v = Vi - 9.8 t v = 0 at top 0 = .5 V - 9.8 t so t = .5 V/9.8 and 2 t = total time aloft = V/9.8 at max height there is no vertical ...
*August 18, 2014*

**physics**

You are welcome :)
*August 18, 2014*

**physics**

if none were added dN/dt = k N number produced per second = 10 number lost per second = k n so dN/dt = 10 - k N N is maximum when dN/dt = 0 0 = 10 - k (1000) k = .01 so we know that for this fission reaction (without the inflow) dN/dt = -.01 N dN/N = -.01 dt ln N = -.01 t + C ...
*August 18, 2014*

**probability**

first red = 8/24 second blue = 4/23 so (1/3)(4/23) = 4/69
*August 17, 2014*

**Engineering maths**

outside dimensions of deck are L and W inside dimensions of deck are 30 and 22 so Area of deck = L W - 660 so L W - 660 = 480 L W = 1140 if x = deck width Length L = 30 + 2x W = 22+2x so (22+2x)(30+2x) = 1140 multiply out and solve quadratic
*August 17, 2014*

**physics**

I think they mean total acceleration up
*August 17, 2014*

**physics**

Vi = a t = 32 * 4.1 = 131 m/s at burn out h = (1/2)32 (4.1)^2 = 269 meters at burn out then v = Vi + a t at top v = 0 0 = 131 - 9.8 t t = 13.4 seconds coasting up h = 269 + 131 (13.4) -4.9 (13.4)^2
*August 17, 2014*

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