Saturday

November 28, 2015
Total # Posts: 22,925

**Math**

Google "permutations" by the way.
*June 28, 2015*

**Math**

10! /(10-3)! = 10!/7! = 10*9*8
*June 28, 2015*

**I doubt this data**

coef of friction = 9.60 ? That is very unusual. Is a slap a slab ? Is a flow something a floor? There are two conditions here. The first is before the block starts to slip on the slap and the static friction rules In that case F = 100 N m = 40 + 10 = 50 kg a = 100/50 = 2 m/s^2...
*June 28, 2015*

**St. Basil's school. Physics**

T - 2 pi sqrt (L/g) or in other wors T = k sqrt L 1.44 /.36 = sqrt L1/sqrt L2 L1/L2 = (1.44/.36)^2
*June 28, 2015*

**Physics**

North of east is not a direction Do you mean Northeast? North by East? North North East ? I will assume Northeast which is 45 degrees north of east If so then: North 3 + 5 sin 45 = 6.54 East= 0 + 5 cos 45 = 3.54 distance = sqrt (6.54^2 + 3.54^2) = 7.43 miles tan angle north of...
*June 28, 2015*

**chem org**

bond of two polar molecules one side +, the other side - Try water for example http://www.google.com/search?q=dipole+dipole+bond+examples&ie=utf-8&oe=utf-8
*June 28, 2015*

**physics**

F = G M m/R^2 F/m = G M/R^2 = g wherever G Me/Re^2 = g earth G Mm /Rm^2 = g moon so g moon / g earth = (Mm/Me)(Re/Rm)^2 = (7.36/5.98)(10^-2)(6.37/1.74)^2 = .165 1/.165 = 6.06
*June 28, 2015*

**Algebra**

if 3 x = 18 divide both sides by 3 similarly if 25 x = 50 divide both sides by 25 115 + 118 + 81 + 8 = 322 so 2 x + 322 = 360 subtract 322 from both sides 2 x = 38 divide both sides by 2
*June 28, 2015*

**math**

10 /x^2 = 3 3 x^2 -10 = 0 x = [ 0 +/- sqrt (0 + 120) ] / 6 x = sqrt(120) / 6 = sqrt(30) /3
*June 28, 2015*

**physics**

F = k x = 2.5 Newtons You can not find the period without knowing more, for example the mass. 2 pi/T = sqrt (k/m)
*June 27, 2015*

**Math**

Yes
*June 27, 2015*

**Calculus, derivatives**

they just add dy/dx = a^x ln a + a x^(a-1)
*June 27, 2015*

**calc**

circles stacked to make hemisphere of radius 4 Volume = (1/2) (4/3) pi r^3 = (2/3) pi (4^3)
*June 27, 2015*

**Physics**

cos 45 = sin 45 so both are 550 cos 45 = 550 (sqrt 2)/2
*June 27, 2015*

**Physics**

question does not make sense. What is the heading?
*June 27, 2015*

**science**

The same folks say that pi is 3.00 :)
*June 27, 2015*

**alegbra**

8 x^2 - 7 x - 6 = 0 x = [ 7 +/- sqrt (49+192)] /16 x = [ 7 +/- 15.5 ] / 16 x = 1.406 or -.531
*June 27, 2015*

**Pre Calculus**

4 along x axis 9 along hypotenuse sloping down so y = - sqrt(81 -16) = -sqrt(65) so sin T = -sqrt(65) /9 so csc T = 1/sin T = -9/sqrt 65 cot T = cos T/sin T = (4/9 ) / -(sqrt 65)/9 = 4/sqrt 65 = (4 sqrt 65) / 65
*June 26, 2015*

**Math**

A 10 + 4 = 14 so yes B 16+3 = 20 ??? C 2 - 13 = -11 which is not to the right of -10 on number line D 18 + 15 = 33 is less than or equal to 31 ???
*June 26, 2015*

**Social Impact of Technology**

I could goon forever about this act and its mismanagement and corruption ( I am from Gloucester ) but the answer they want is: "..... focused more on sustainable yield approaches to U.S. fisheries. ...."
*June 26, 2015*

**Math**

I guess maybe you mean (3c/4) - 1 > 1 3 c / 4 > 2 3 c > 8 c > 8/3
*June 26, 2015*

**algebra**

say 100 total students to make it easy let y = year - 2009 to make it easy M101 2009 13 2014 25 s = m y + b m = (25-13)/5 = 12/5 13 = (12/5) 0 + b so b = 13 s = (12/5)y + 13 M222 2009 25 2014 7 s = (-18/5)y + 25 so when is (12/5)y + 13 = -18 y/5 + 25 ??? 30 y/5 = 12 y = 2 so ...
*June 26, 2015*

**physics**

.0005 * 731 + 47 * x = 0 x = -.00778
*June 26, 2015*

**physics**

s = slope angle sin s = 1.7/5.8 so s = 17 deg so cos s = .956 1) m g h = 45 * 9.81 * 1.7 2) (1/2) m v^2 = (1/2) (45)(2.6)^2 3) normal force = m g cos T = 45*9.81*.956 = 422 N friction force = .13 * 422 = 54.9 N work against friction = 54.9*5.8 b) Total work done = increase in ...
*June 26, 2015*

**physics**

I thought I showed you how to do this. You still have not told us what you see on that diagram. http://www.jiskha.com/display.cgi?id=1435166331
*June 25, 2015*

**science**

How about 2 C8H18 + 25 O2 ---> 18 H2O + 16 CO2 C 16 left 16 right H 36 left 36 right O 50 left 18 + 32 = 50 right Conservation of mass means there must be the same atoms of each element left and right. In a chemical (not nuclear) reaction one element does not change into ...
*June 25, 2015*

**Physics**

Depends, At same size and speed yes because feather is lighter for the same geometry or has more area for the same mass.
*June 25, 2015*

**physics**

a. h = (1/2) g t^2 so 4.9 t^2 = 15 find t b. v = gt c. u is constant. There is no vertical force u = 4/t
*June 25, 2015*

**Physics**

work = change in Ke = (1/2)(2)(1^2-4^2) = -15 J negative because energy taken out not put in work = force * distance in direction of force -15 = F (10) F = -1.5 N impulse = change in momentum I = 2 ( 1 - 4) = -6 kg m/s
*June 24, 2015*

**whoops**

or one fourth of the way from S along the altitude from S to the line connecting O and O SHOULD BE a distance A/4 along the altitude from S to the line connecting O and O
*June 24, 2015*

**physics**

Well, I do not see your diagram. However the angle from O to S to O is usually considered to be 120 degrees so if the distance from S to O is A and the mass of an O is m then CG is along the line joining S to the midpoint of O - O How far from S ? Well we have 2 m on the left ...
*June 24, 2015*

**algebra**

Yes although 7 + 1 x is the same as 7 + x because one times anything is that same old anything.
*June 24, 2015*

**algebra**

I answered one like this a few minutes ago. You should be able to use that to figure it out.
*June 24, 2015*

**world history**

......but when I Google Neanderthal brain size I find they have bigger brains than we. What makes you think they are our ancestors? Humans and Neanderthals lived in Europe at the same time for a while. Perhaps they interbred, but I am not sure they count as our ancestors. http...
*June 24, 2015*

**world history**

picture framing? Perhaps farming? If farming, then: herding is most often practiced by nomadic tribes who do not farm (cowboys?) nomads do not usually farm farmers may hunt, but only on vacation during deer season. I suspect that to really develop the use of metals you need to...
*June 24, 2015*

**world historia**

Yes, the main thing I remember is that they were forgotten for a long time :)
*June 24, 2015*

**algebra**

5 - 3 x
*June 24, 2015*

**world history**

As far as I know both used brick walls. Also there is some evidence that Harappan script resembled Sumerian cuneiform but I am not sure it is considered cuneiform. I guess I might pick B
*June 24, 2015*

**Physics**

at one meter from the hinge at the wall you have 491 N down at 1.5 meters from the wall you have T sin 30 up moments about hinge at wall yield: (T sin 30) * 1.5 = 491 * 1 T (1/2)(3/2) = 491 T = 491 * 4/3
*June 24, 2015*

**science**

16 = .380 * Normal force
*June 24, 2015*

**Physics**

check the replies listed below your question. The numbers are different but the method should be clear. eg http://www.jiskha.com/display.cgi?id=1426366344
*June 24, 2015*

**Physics**

during free fall for 3.5 s: v = g t = 9.8*3.5 = 34.3 m/s when we pt on the brakes h = (1/2) g t^2 = 4.9 (3.5)^2 = 60 meters so far, now we stop we are going at 34.3 m/s and slow down at 2 g 0 = Vi - 2 g t so t = 34.3 /19.6 = 1.75 seconds braking h = Vi t - (1/2)(2*9.8) t^2 = ...
*June 24, 2015*

**maths**

x y = 25/42 x (-20/7) = 25/42 x = (25/42)(-7/20) x = (5/4)(-7/42) x = (5/4)(-1/6) x = -5/24
*June 24, 2015*

**Algebra**

Hey, I just did one like this for you.
*June 24, 2015*

**Algebra**

x = length y = width x + 2 y = 9000 or x = 9000 - 2 y A = x y so A = (9000-2y)y 2 y^2 - 9000 y = - A y^2 - 4500 y = -A/2 y^2 - 4500 y +(4500/2)^2 = -A/2 + 5,062,500 (y-2250)^2 = -(1/2)(A-10,125,000) so width = 2250 length = 4500 area = 10,125,000 m^2
*June 24, 2015*

**Math**

7 * pi *r^2 = 137.375 so r = sqrt (137.375/[7 pi]) then C = 2 pi r
*June 24, 2015*

**pragati s.s.h.s.s**

For example Joules is Force*distance = mass * acceleration * distance kg m/s^2 * m = kg m^2/s^2
*June 23, 2015*

**physcial science**

Well, speed of sound in air is around 343 m/s depending on pressure, humidity etc the lightning light travels so fast we will assume we see it when it happens. so d = 7.9 s * 343 m/s = 2710 m or 2.7 km away t = 2.7 km /20 km/h = .135485 hours * 60 min/hr = 8.1 minutes
*June 23, 2015*

**Algebra**

No way. I just did one like this for you.
*June 23, 2015*

**Algebra**

do you know about completing the square? (3x + y)(3x+y)= 9 x^2 + 6xy + y^2 6 y = 16 y = 8/3 y^2 = 64/9 so 9 x^2 + 16 x + 64/9
*June 23, 2015*

**Algebra**

(z-2+3i)(z-2-3i) = 0 now multiply
*June 23, 2015*

**Algebra**

when b^2 - 4 a c is negative a^2 - 400 <0 -20 < a < +20
*June 23, 2015*

**Science**

radius = 5 meters .18 m/s^2 is probably the centripetal acceleration. I can not imagine why it is called "rate". acceleration = v^2/R v^2 = .18 * 5 = .9 v = .95 m/s
*June 23, 2015*

**ICP**

By the way I have no idea what ICP is and I just happened to stumble on your question. Identify your subject next time please.
*June 22, 2015*

**ICP**

10 * 30 cos 25 Work is component of force in direction of motion times distance moved.
*June 22, 2015*

**history**

Assume you mean France. Other countries (eg: USA) managed to install something like democracy without anything like happened in France, but you better read up on the subject and say a lot more than I just did. In particular read previous responses to this question below.
*June 22, 2015*

**Algebra**

22.5 x + 35 (1250 -x) = 27.5 (1250)
*June 22, 2015*

**typo**

You gave grades for 4 tests not five. I will assume total of 5 (70 + 80 + 79 + 69 + x)/5 = 80 (298 + x) = 80 * 5 x = 80 * 5 - 298 x = 102 I think this kid is in trouble :(
*June 22, 2015*

**algebra**

first = x second = x+10 third = 2x-5 sum = 45
*June 22, 2015*

**physics**

20 g ( 4.18 J/g deg C )(30 deg C-10 deg C) = 1672 J which is closer to 1700 than to anything else on your list.
*June 22, 2015*

**MATH**

Henry x sister 12 friend 12 - 6 = 6 so gave away 12+6 = 18 so he was left with 2*18 = 36 so he had 36 + 18 = 54
*June 22, 2015*

**Math**

Needs a modern fuel efficient car, or a newer text book :)
*June 22, 2015*

**Math**

144.6/4 = miles per hour 144.6/12 = miles per gallon
*June 22, 2015*

**physics**

25 = .40 a
*June 22, 2015*

**Science**

2.34/12 = .195 .16/1 = .16 (I assume hydrogen atoms not molecules?) .46/14 = .0329 1.04/16 = .065 for every nitrogen atom we have .065/.0329 = 1.97 O and .195/.0329 = 5.9 C and .16/.0329 = 4.86 H C6 H5 N O2
*June 22, 2015*

**physics**

for part b kinetic energy at ground - F * h = potential energy at top (1/2) (1) (23)^2 - F (17.8)= 1*9.81*17.8 264.58 - 17.8 F = 174.6 F = 5.05 Newtons I get
*June 21, 2015*

**Calculus(math)**

To get distance from the velocity you must integrate.
*June 21, 2015*

**Physics**

circumference = 2 pi r = 19.48 meters a) 36/360 = .1 .1 * 19.48 = 1.948 meters b) angle in radians * r = distance 36 * 3.1 = 111.6 meters c) 36 * 19.48 = 701
*June 21, 2015*

**physics 1401**

-5 - -3 = -2 -4 - 8 = -12 sqrt (4 +144) = 12.2
*June 21, 2015*

**physics**

m g h = (435-205) h = (435-25)/( 30*9.81)
*June 21, 2015*

**physics**

initial Ke = (1/2)(54.5)(1.95)^2 = 104 J energy added = 80-265 = - 185 J so if no change in elevation final ke would be 104-185 = - 81 J actual final ke = (1/2)(54.5)(5.95)^2 = 965 J so the gravitational PE loss (dropped down to gain speed) = 965 + 81 = 1046 J or delta PE = -...
*June 21, 2015*

**physics**

work done by push = 154 * 6.4 J positive work done by friction = -50*9.81*.24*6.4 J negative work done by normal = work done by weight = ZERO because force perpendicular to displacement
*June 21, 2015*

**World War 2**

Google "peace in our time "
*June 21, 2015*

**physics**

oh well, I suppose I can pretend to know what the question is. v = vertical speed Vi = initial vertical speed so Vi = 10 sin 53.1 How long rising? v = Vi - g t = Vi - 9.81 t at top, v = 0 so tt = Vi/9.81 at the top (calling tt the top time) How high at top? h = 24 + Vi tt - 4....
*June 21, 2015*

**math**

Your initial velocity component up which you are calling Vo is 1750 sin 10 so Vo = 304 ft/s ( I can hardly believe you are using feet not meters but well here g will be 32 ft/s^2) Your distance down range, x = u t where your constant horizontal speed u = 1750 cos 10 (that is ...
*June 21, 2015*

**Math**

Oh and also it is imaginary for (2-x) negative or x > 2 In other words the new inverse curve is open to the left with a vertex at (2,-3)
*June 21, 2015*

**Math**

well, first of all that is a parabola as you know. If you invert it, it is likely to have two values of the ordinate for every value of the abscissa. In other words the inverse will not likely really be a function. However to do what you want to do, use x for y and y for x and...
*June 21, 2015*

**Chemistry**

nah, 10^23/10^23 = 1 perhaps write it as (6.70/6.02)(10^23/10^23) * 18.02
*June 21, 2015*

**Math 11 u**

Or now that I know the answer: w^2 + 4 w - 117 = 0 (w-9)(w+13) = 0
*June 21, 2015*

**Math 11 u**

w^2 + 4 w - 117 = 0 Do you know how to use the quadratic equation? w = [ -4 +/- sqrt (16 + 468) ] /2 w = -2 +/- (1/2) sqrt 484 ) w = -2 +/- (1/2)22 w = -2 +/- 11 use the + root w = 9 then L = 13 ============== check 9 * 13 = 117 sure enough
*June 21, 2015*

**Chemistry**

Fe = 56 2N =2*14 = 28 6O = 6*16 = 96 so the stuff is 180 grams/mol .555 * .650 = .361 mols present .361 * 180 = 65 grams
*June 21, 2015*

**Physics**

both go distance d car A takes time t car b takes time (t - 1) d = 50 t d = 60 (t - 1) so 50 t = 60 t - 60 10 t = 60 t = 6
*June 21, 2015*

**Typos, math, physics**

Would everyone who posted math and physics problems this morning please go back and check for typos? It is difficult to guess what you mean and we do not have your text book.
*June 21, 2015*

**Nobody knows**

You did not tell us: 1. radians per second or rpm or something about speed. 2. jow high the axis of the wheel is.
*June 21, 2015*

**chem**

http://www.google.com/search?q=potassium+carbonate+formula&ie=utf-8&oe=utf-8
*June 21, 2015*

**chem**

CO3-- is negative two In other words it has two more electrons than protons K + is plus one. in other words it is missing an electron To make it all come out a neutral solid salt you need two K ions for every one carbonate ion so K2CO3 GOOGLE potassium Carbonate https://www....
*June 21, 2015*

**physics**

kg * m/s * m/s = kg m^2/s^2 By the way force = mass * acceleration which is kg m/s^2 in Newtons force * distance = work which is energy in Joules so energy = kg m/s^2 * m = kg m^2/s^2
*June 20, 2015*

**Algebra**

The y axis intercept is when x = 0 Here when x = 0 y = (-3)^2(-9) = 9 * -9 = -81 The x intercepts are when y = 0 which is when x = 3 (just barely hits the axis) and when x = 9 On the right is when x is very large positive. That is y ---> x^2 (x) = x^3 rising on the left x ...
*June 20, 2015*

**homewrok**

(tagged/total) = (8/60)= 200 / x 2/15 = 200/x 1/15 = 100/x x = 1500
*June 20, 2015*

**Calculus**

Perhaps you mean x = delta x = 1 ??? y = 7 x^-1 dy/dx = 7 (-1)x^-2 = -7 x^-2 if x = 1 y = 7/1 = 7 dy/dx = -7 delta y = -7 delta x if delta x = 1 delta y = -7 Y + delta Y = 7-7 = 0 real answer y (2) = 7/2 = 3.5
*June 20, 2015*

**ALGEBRA**

let age = x x/4 + x/5 + x/3 + 13 = x LCD = 60 60 x/4 + 60 x/5 + 60 x/3 + 13*60 = 60 x 15 x + 12 x + 20 x + 13 * 60 = 60 x 47 x + 13 * 60 = 60 x 13 x = 13 * 60 x = 60
*June 20, 2015*

**physics**

It fell 100 meters. h = (1/2) g t^2 100 = 4.9 t^2 t = 4.52 seconds
*June 20, 2015*

**Physics**

yes If you were a ship designer you would know that for a model and full scale under gravitation v/sqrt(gL) is the same model and full scale. if you divide the lengths by 100, you divide the speeds by 10 Google Froude number - here : http://www.engineeringtoolbox.com/froude-...
*June 20, 2015*

**Physics**

The forces will certainly not be the same but much smaller on the model. The acceleration is the question. h = H/10^2 m = M/10^6 because volume is 1/100^3 V = sqrt (2 g H) v = sqrt (2 g h) so v = V/10 acceleration is velocity /time time is distance/velocity so acceleration = k...
*June 20, 2015*

**Physics**

mass = 9/g = 9/9.81 kg = .917 friction or other force holding it back = 15 Newtons so F - 15 = ma = .917 (a) but a = 14/4 so F = 15 + .917(14/4) = 18.2 N
*June 19, 2015*

**Physics**

F = m g down - 40 up = 10(9.81)-40 = 58.1 N down a = F/m = 58.1/10 = 5.81 m/s^2 down
*June 19, 2015*

**math**

Note Mathmate response to the question below titled Calculus AB
*June 18, 2015*

**math**

be careful with parentheses like use dy/dx= (x^2+3y^2)/ ( 2xy ) http://www.wolframalpha.com/widgets/view.jsp?id=e602dcdecb1843943960b5197efd3f2a y = +/- x (cx-1)^.5
*June 18, 2015*

**Math**

s = 2 f/3 s = 4 (f+5) /7 -------------------- 2 f/3 = 4 f/7 + 20/7 2*21 f/3 = 4*21 f/7 + 20*21 /7 14 f = 12 f + 60 2 f = 60 so f = 30 s = 2 f/3 = 20 ======================= check s/f = 20/30 = 2/3 yes s/(f+5) = 20/35 = 4/7 yes, it worked
*June 18, 2015*

**stats**

http://davidmlane.com/hyperstat/z_table.html
*June 18, 2015*