# Posts by Damon

Total # Posts: 29,993

physics
+250 :) weight = m g = 55*9.8 = 539 Newtons That is the normal force on the floor Max friction = .56*539 = 302 N

physics
weight = w = m g normal force = m g cos theta ratio = cos theta so cos 17 and cos 30

calculus
Oh, intercepts y = x^3-6x^2 0 = x^2 (x-6) bounced off x axis at x = 0 crossed x axis at x = 6

calculus
slope = 3 x^2 -12 x =3 x (x-4) second derivative (curvature) = 6 x - 12 so the slope is 0 at x = 0 and at x = 4 at x = 0 is that a min or a max or in inflection point? second derivative = -12 That is a maximum, starts down from there at x = 4 is that a min or a max or an ...

Chemistry
CuCO3 = 64+12+48 g/mol = 124 g 31/124 = .25 mol CO2 = 12+32 = 44 g/mol so 11 g for .25 mol for CuO, subtract:) 31-11 = 20 grams check: CuO = 64+16 = 80 g/mol .25*80 = 20 grams sure enough

calculus
two negative numbers can not add to +1

calculus
b.f(x)=x^3=x-4 Typo, makes no sense c. f(2)=8 f(-1)=-1 so 9/3 average slope =3 f' =3x^2 3 x^2 =3 x= sqrt(1) which is 1 !!!! but also -1 d f(4) = 2 f(0) = 0 so slope = 2/4 = 1/2 f' = (1/2)x^-1/2 = 1/2 x = 1 again

Math
a + b + c = 975 a - x = 12 b - x = 345 c - x = 126 --------------add a+b+c -3 x = 483 so 975 - 3 x = 483 3 x = 492 x = 164

physics
mapple Vapple +mweath*0 = (mapple+mearth) V V = Vapple (mapple)/(mapple+mearth) so yes mapple/(mapple+mearth) is not very big it might be kind of hard to measure :)

physics
The earth moves under your feet (but just a little).

Math
L(1-cosT) = 1/3 foot sin T = 4 feet/L so L sin T =4 1-cosT = 1/3L L sinT = 4 cosT = (3L-1)/3L so cos^2T = (9L^2 -6L+1)/9L^2 so 1-cos^2T = (6L-1)/9L^2 which is sin^2 T but sin^2T =16/L^2 so 16/L^2 = (6L-1)/9L^2 144 = 6L-1 6L = 145 L = 24.2 feet check my arithmetic!

calculus
dV = surface area * dr so dr/dt = dV/dt/(4 pi r^2) dr/dt = 2 /(4 pi *64)

math
well, you just said math, not calculus, which is why I completed the square to find the vertex of the parabola in the other problem. 3 4 5 triangle x = 4 y = 3 hypotenuse = 5 dy/dt = -2 ============================= x^2 + y^2 = 25 2 x dx/dt + 2 y dy/dt = 0 dx/dy = -(y/x)dy/dt...

math
r = x (1000-2x) r = 1000 x -2 x^2 2 x^2 -1000 x = -r x^2 - 500 x = -(1/2)r x^2 -500 x + 250^2 = -(1/2)r + 250^2 (x-250)^2 = -(1/2)(r-2(250)^2 ) x = 250 r = 2*250^2 = 125,000

Algebra
[ (x/3) -5 ] 7 = 28 (x/3) -5 = 4 x/3 = 9 x = 27

calculus
check end points f(-2) = -2+8 = 6 f(2) = 2-8 = -6 now find where derivative is zero f' = 1 -3x^2 = 0 when x = 1/sqrt3 or x = -1/sqrt3 if x = 1/sqrt 3 f = 1/sqrt3 -1/3sqrt3 =(2/3sqrt3) if x = -1/sqrt3 f = -1/sqrt3 +1/3sqrt 3 = -(2/3sqrt3) so the max and min are at the end ...

calculus
Well, try one of them. function is continuous and differentiable from 1 to 3 (note not at zero) f(3) = 3-1/3 = 8/3 f(1) = 0 [f(3)-f(1)]/(3-1) = 4/3 so where is the derivative 4/3? f'(x) = 1 + 1/x^2 where does 1+1/x^2 = 4/3 ? 1/x^2 = 1/3 x = sqrt 3 yes, that is between x = ...

Physics
pm=1.6gcm^-3 nonsense V = 40 cm^3 so mass = 20 + 40 * density of Hg which is not 1.6 g/cm^3

Math
original = p cents / pizza 10 p = total cost 9(p+60) = same total cost so 10 p = 9(p+60) p =540 cents = 5.40 per pizza so \$54

math
n = original 1.2 n = before 300 .2 * 1.2 n = 300 so 1.2 n = 1500 n = 1250 books originally ===================== check ===================== 1.2 * 1250 = 1500 +300 = 1800 1.2*1.2*1250 = 1800 sure enough

Algebra 1
x = [2p+/-sqrt(4p^2+32p^2) ]2 = [2 p + sqrt(36 p^2) ]/2 = [2 p + 6 p ]/2 = 4 p

Math
(43/2)(3/4)= 129/8 left after tacos (2/3)(129/8) used for burgers times 4 for number of 1/4 lb burgers 4(2/3)(129/8) = 129/3 = 43 burgers

another subtraction error
360 - 12 = 348 348 = 23 t -23t/2 696 = 23 t t = 30.3 a = 23/30.3 = .759 m/s^2

Physics
freight train goes 6 t our train goes 6t+360 Vi = 29 Vf = 6 a assumed negative v = Vi - a t 6 = 29 - a t a t = 23 d = 6t+360 = 29t-(1/2)a t^2 360 = 23 t -(1/2)(23 t) 720 = 23 t t = 31.3 seconds to crash a = .74 whoops, forgot the .4 seconds to react we go 14.5 m he goes 2.4 m ...

Algebra 1
You are welcome.

Algebra 1
n + n+1 + n+2 + n+3 + n+4 = 5 n + 10 so (5n+10)/5 = 13 5n+10 = 65 5 n = 55 n = 11 so 11 , 12, 13 , 14, 15 old sum was 65 new sum is 53 difference is 12 so 12

Physics
Not really. I bet you have heard the word "Impulse" that is force * time which is change of momentum F = m a = m dv/dt so F dt = m dv = "impulse" but m dv is change in m v and m v is "momentum therefore F * time = change in momentum = impulse

Physics
change in momentum = force * time force up = 800 -55(9.81) = 260 N net up force so momentum = m Vi = 260*.25 = 65 so Vi = 65/55 = 1.18 m/s up (1/2)mVi^2 = m g h h = Vi^2/[2(9.81)] = .071 meters = 7.1 cm

algebra
x^2 - 3 x = 4 x^2 -3 x +(3/2)^2 = 4 + 9/4 (x-1.5)^2 = (1/4)(16 + 9) (x-1.5)^2 = (1/4)(25) = 25/4 x-3/2 = +/- 5/2 x = 3/2 +/- 5/2 x = 4 or x = -1

Algebra 2
You are welcome.

Algebra 2
w = x L = (x+1) H = (x-4) w L H = 84 so x(x+1)(x-4) = 84 but the easy way is to look at the answers listed 7 is one bigger than 6 4 is one bigger than 3 so it must be one of the last two if x = W = 6 L=7 H=6-4 = 2 that works if x =W= 4 L = 5 etc, does not work so 2,6,7 works (...

Physics
Fe 7.87 g/cm^3 Ag 10.5 g/cm^3 Viron* 7.87 + Vag*10.5 = 30 Viron + Vag = 20.4 ok?

Physicsthe weight on e
Our spring scales would not work on the moon correctly. We would have to multiply the measurement in grams or kilograms by 6 to get the right answer :) On the other hand a balance scale would work fine.

Physics
This is the second question in a row which confused mass and weight or force. Are you using the same old physics book I wonder?

Physics
well, 250*0.85 = 212.5 cm^3 so it displaces 212.5 grams of water assuming water has density of 1 gram/cm^3 If your book does force in grams, that is the answer. However that 212.5 grams is really the MASS of water displaced. To get the force up you really should multiply that ...

Physics
by the way, what we worked with here was mass, not weight. If this is a Physics course, your book should do mass in kg and weight in Newtons or mass in g and weight in dynes. weight = mass * acceleration of gravity. mass is the same on another planet, weight is different.

Physics
holds 40 g water that is volume = 40 cm^3 since density of water is about 1 g/cm^3 mass = 20 + 40*density of Hg density of Hg = 13.5 g/cm^3 so mass = 20 + 40*13.5 grams

Algebra 1
You are welcome.

Algebra 1
a = b + 2 c b = 2 c so a = 2 c + 2c = 4 c a + b + c = 77 4 c + 2 c + c = 77 7 c = 77 c = 11

math
you could do this by dividing the areas but that is not safe because it might not be exact one way or the other so 6 * 1.5 = 9 8 * 1.5 = 12 6*8 = 48 exactly

Math
4b+2p = 34 p = b-4 4 b + 2(b-4) = 34 4 b + 2 b - 8 = 34 6 b = 42 b = 7

algebra
3 z^2 = -108 z^2 = -36 z = +/-6 sqrt -1 = +/- 6i

algebra
5 x^2 = 651-536 = 115 x^2 = 23 x = +/- sqrt 23 = +/- 4.80

Math
49 - 2v

Math
three choices for the first digit 2 choices for the second 1 choice for the third 3*2*1 = 6 1 2 3 1 3 2 2 1 3 2 3 1 3 1 2 3 2 1

algebra
54 = 2*27 = 2*3*3*3 6 and 9 is 15 so (w-6)(w-9)

Calculus
5[xdy + ydx ] +x^2 dy+y(2x dx)=0 dy(5x +x^2) + dx(5y+2xy) = 0 dy/dx = =(5y+2xy)/(x^2+5x)

Chemistry
Ph determination

Chem 111
1000 kg/m^3 V = pi (d^2/4)h d = 6 ft = 1.83 m h = 17.5 ft = 5.33 m so V = [pi(1.83^2)/4 ]5.33 m^3 mass= 1000 * V in kg there are about 2.2 pounds/kg

Math
(2*27 + n)/3 = 29 54 + n = 87 n = 33

Need help with vector questions posted below
+1 1 3 -1 2 n +2 m 1 determinant = 0 2 + 2n -3m -12 -nm +1 = 0 2n-9 -m(3+n) = 0 m = (2n-9)/(3+n)

maths
everything in thousands two points on line (4,22) and (6,30) (30-22)/(6-4) = slope so slope = m = 4 c = 4 n + b 22 = 16 + b b = 6 so c = 4 n + 6 if n = 4.5 c = 4(4.5) + 6 c = 18+6 c = 24 so 24,000

Vectors - Maths [Second Question]
+1 -1 +2 +1 +2 -4 +m +6 -12 det = 0 -24 +12 +4m -4m +24 -12 = 0 I get any old m

Vectors - Maths
+1 1 3 -1 2 n +2 m 1 determinant = 0 2 + 2n -3m -12 -nm +1 = 0 2n-9 -m(3+n) = 0 m = (2n-9)/(3+n)

calculus
f(x+h) = 1/(2x+2h) f(x) = 1/2x f(x+h)-f(x) = (2x -2x-2h)/2x(2x+2h) = -2h/(4x^2+4xh) divide by h = -2/(4x^2+ 4xh) let h--->0 = -2/4x^2 = -1/2x^2

Calculus
Oh well h = 9 cm r = (6/12)9 = 4.5 cm dV = pi r^2 dh so dV/dt = pi r^2 dh/dt -3 cm^3/min = pi (4.5)^2 dh/dt so dh/dt = -3/[ pi(4.5)^2] about .047 cm/min

Calculus
No. The answer is in cm/min not cm^4/min. I did not check the arithmetic.

Calculus
I and also Steve have answered a million of these. For example: http://www.jiskha.com/display.cgi?id=1415757944

incomplete
earned how much in a year, call it x percent = 100 (x/9000)

Maths
By the way for small angles most of us assume sin theta = tan theta = angle in radians where angle in radians = angle in degrees * pi/180 then the arc length = chord length = R theta

Maths
LOL, If you really want to do it as an isoceles triangle with equal legs of length 5.06 e13 miles then sin .5 minutes = (x/2)/5.06e13 x = 5.06 e13 * 2 sin .5 min sin .5 min = sin (.5/60) degrees = .000145441 times 10.12 e13 = .00147186292 e13 = 1.47 e10 again:)

my typo
found error so your arc length in light years is 2 pi(8.611)/(60*360) = .0025048 light years which is 1.47e10 miles (those are land, not nautical miles) To get it go to Google and type .0025048 light years = miles and hit enter or use calculator and speed of light.

Maths
Clearly parallax is not a problem at this distance :)

Maths
You are right, I have an arithmetic error I estimate that 8.6 light years ia about 5.06 * 10^13 or 5.06e13 miles one minute is 1/21,600 of the circumference [ that is 1/(360*60) because 360 degree and 60 minutes per degree] circumference = 2 pi r = 2 pi * 5.06e13 = about 31 ...

Maths
for that pesky e notation: http://www.mathsisfun.com/numbers/scientific-notation.html look at example at the end: Example: 3.12E4 is the same as 3.12 × 104 3.12E4 = 3.12 × 10 × 10 × 10 × 10 = 31,200

Maths
Oh my, you really need another bit of spherical trig, namely the measure of an angle in "radians" there are 2 pi radians in a circle of 360 degrees so the circumference is C = 2 pi radians * R the handy thing is for any angle in radians now arc length along circle = ...

Maths
2*1.5 = 3 m^2

physics (mechanics)
dU = work done=potential change or force dr = dU U = A/r dU/dr = F = -A/r^2 Sign of A depends on attractive or repulsive.

Pre Calc
These are straight lines, they cross once. 2.4 +.3 t = 1.1 + .7 t .4 t = 1.3 t = 13/4 = 3 1/4 years

Math
pre tax = 1.18 p 1.18 p * 1.06 = 37.20 so p = 37.20 / (1.18*1.06)

math - calculus help!
oh well, not that hard V = (1/3)pi r^2 h r = 7 h/24 so V = (1/3)pi (7/24)^2 h^3 dV/dh = pi (7/24)^2 h^2 dh when h = 10 dV = pi (70/24)^2 dh dV = pi (35/12)^2 dh

math - calculus help!
You could use a fancy formula for volume of a cone and differentiate it to find dV/dh but if you just draw a picture you can see that the area of the surface * dh is the added volume for added dh

math - calculus help!
radius/depth = 7/24 what is radius when depth = 10? 7/24 = r/10 r = 70/24 = 35/12 now the change of volume with depth h is the surface area area * dh = dV pi r^2 dh = dV pi r^2 dh/dt = dV/dt = 12 ft^3/m pi (35/12)^2 dh/dt = 12 dh/dt = .449 ft/min

Pre calc
Good, you have two different ways now :)

Pre calc
slope = (20-13)/(4-3) = 7 also for any (x,y) slope = (y-20)/(x-4) so 7 = (y-20)/(x-4) 7 x - 28 = y - 20 so y = 7 x -8

THANK YOU DAMON
You are welcome :)

Social Studies
a.They conquered inland kingdoms, which they turned into a trading empire. --------------- The big advantage the Portuguese had over Arabs etc in the Indian Ocean was big ships with big guns. They did not try to march inland. India was a civilized country with real armies, not...

Social Studies
Yes, maybe b then c

Social Studies
It was particularly the various competing Christian missionaries that made the Japanese mad, and they were very angry about what happened in the Phillippines. The Dutch were allowed to hang out in a Nagasaki trading post because they did not try to convert people or push them ...

Social Studies
Particularly this excerpt: "Japan had been closed to the outside world for 250 years. When foreign people entered Japanese waters, even if they were shipwrecked by accident, they were interned in jails and some of them were killed (Lubor 33). The reasons for the Japanese ...

Social Studies
Ah yes, this is short and sweet http://willamette.edu/~rloftus/perry.html

Social Studies
I am looking for a link for question 2

Social Studies
no, no

Social Studies
Now for question 2, perhaps we better look at the start of American-Japanese relations. Did you read about only the Dutch being allowed there before that fleet arrived?

Social Studies
here is a wiki for Goa: http://www.google.com/search?q=goa+india&ie=utf-8&oe=utf-8

Social Studies
Well, I suppose I could give you some link to a wiki or something, but first think about it. The Portuguese ended it all in India long this after with Goa. Can you imagine a little country like Portugal marching around India ? They were sea farers

Social Studies
In question 1, remember we are talking about the Portuguese, not some tea company.

Social Studies
Ah, what do you think? The answer to question 2 is petty dramatic and amazing.

Pre calc
y = m x + b y = -(3/2) x +3/4 or 4 y = -6 x + 3

History
Well, my choices would be: 1. Prince Henry the Navigator, Bartolomeu Dias, Vasco da Gama .... so D 2.I would say B 3. See question 1.

Math
65*50 = 6500/2 = 3250 ft^2 so 1625/3250 \$/ft^2

American Government
County responsibility is now chiefly law enforcement (sheriff and county jail) and registry of deeds and such. However it still exists and the towns and cities have not take over all county responsibilities.

American Government
Although our ounty government has been largely eliminated over the last decade, we still have a sheriff etc. Our town governments operate much like our city governments, although often having a Board of Selectmen instead of a City Council. Both towns and cities are often run ...

American Government
http://en.wikipedia.org/wiki/Essex_County,_Massachusetts

Physics
I think it is a dip and v^2/R = 0.15*9.81

Physics
density = 1000 kg/m^3 is easier :) You do not say if you want gage pressure or absolute pressure I will assume gage rho g h = 1000*10*25 =2.5 *10^5 Pascals or N/m^2 if you want absolute pressure add one atmophere or about 1*10^5 for a total of 3.5*10^5 Pascals

Physics
You already said the speed of the boat through the water was 2 m/s The speed over the land is 2-.8 = 1.2 m/s

physics
v^2/R = g or it loses contact m g(h-D) = .5 mv^2 v^2 = g R = .5 g D so m g(h-D) = .5 m *.5 g D =.25 mgD h-D = .25 D h = 1.25 D

Math
anything^0 = 1 so x^3/x^3 = x^0 = 1 y^6/y^6 = y^0 = 1 so 1

asthmatics
assuming it is the height that is 9.5 outside volume = 23 * 15.5 * 11 inside volume = 20 * 12.5 *9.5 now subtract the inside from the outside

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