Sunday
July 5, 2015

# Posts by Damon

Total # Posts: 21,431

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
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

Chemistry
CH3CH2OH + 3O2 => 2CO2 + 3H2O CH3CH2OH is 2*C = 24 + 6*H = 6 + 1*O = 16 = 46 grams/mol so that is 775/46 = 16.85 mols of ethanol so we would get 2*16.85 = 33.7 mols of CO2 CO2 = 12+32 = 44 grams/mol 33.7 *44 = 1483 grams of CO2 Oh my, greenhouse galore
June 18, 2015

Public speaking
June 18, 2015

Public speaking
I am having trouble articulating a reply.
June 18, 2015

Math Trigonometry
tan angle = 6/8 = .75
June 18, 2015

science
For example from that link: " Reason #1: Without wolves and other large predators, ecosystems can go haywire. A 2001 study (PDF) found that when wolves went extinct in Yellowstone, for example, the moose population ballooned to five times its normal size and demolished ...
June 18, 2015

science
Here, click through these 10 pictures http://www.motherjones.com/slideshows/2011/04/wolves-protect-climate-change/seated-gray-wolf-yellowstone
June 18, 2015

science
The animals the lynx eats would get more numerous. The plants and animals that those target animals eat would get scarcer. Whatever they in turn feed on multiplies. The effects work down from that top predator and equilibrium populations of everything in the forest changes. ...
June 18, 2015

physics
v = Vi - g t here Vi = 150 sin 30 = 75 m/s at top v = 0 0 = 75 - 10 t solve for t at top t = 7.5 seconds then if they ask for the height h = (1/2) g t^2 to fall from top = 5 * (7.5)^2 then if they ask for range u = 150 cos 30 range = u t = 150 cos 30 * 7.5 * 2 the 2 is because...
June 18, 2015

divide length dimension by sqrt 2 to get half the area
June 18, 2015

w(w+5) >/= 84 w^2 + 5 w - 84 >/= 0 solve for zero, anything bigger works w = [ -5 +/- sqrt(25 + 336) ]/ 2 w = [ -5 + 19 ]/2 = 7 then L = 12 so anything at least 7 by 12
June 18, 2015

parabola opens down (sheds water) when is it between the vertex and 22 feet? 16 t^2 - 42 t - 3.75 = -22 16 t^2 - 42 t + 18.25 = 0 t = [ 42 +/- sqrt (1764 - 1168) ] / 32 t = [ 42 +/- 24.4 ] /32 t = .55 to 2.07 seconds
June 18, 2015

physics
or in other words half the radius -->4 g then 4 times the earth mass --> another 4 times g
June 18, 2015

physics
mstudent = 810/9.81 = 82.6 kg THE MASS, m in kg, DOES NOT CHANGE WITH g, ONLY THE WEIGHT F = G * Mplanet* mstudent /r^2 on earth 810 = G Mearth * mstudent /rearth^2 on Nerdland F = G Mnerd *82.6 / rnerd^2 so F = G (4 Mearth) * 82.6 / (.25 rearth^2) F = 16 G Mearth * 82.6 /...
June 18, 2015

PHYSICS
(1/2) m Vi^2 + m g h = (1/2) m Vfinal^2 or Vfinal^2 = Vi^2 + 2 g h = 225 + 2 (9.81)(20) = 617.4 sqrt 617.4 = 24.8
June 18, 2015

physics
a - gravity down, air friction up b - friction force exerted on roadway by horseshoe, equal and opposite force exerted by horseshoe on roadway, horse then exerts pull on shaft, shaft pulls back on horse and forward on cart, roadway exerts friction force back on cart c - ...
June 18, 2015

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