Monday
July 25, 2016

Posts by Damon

Total # Posts: 26,553

Math/algebra
Watch out for difference between sample and total population standard deviations. Divide by 9 or divide by 10.
May 17, 2016

Math/algebra
http://www.mathsisfun.com/data/standard-deviation-calculator.html
May 17, 2016

check english please.. romeo and juliet
I am inclined to agree with you.
May 17, 2016

LIMITS CALCULUS
Oh, did not notice that. (-8)^(1/3) that is a complex number e^iT = cos T + i sin T -8 = 8 cos pi + 8 sin pi = 8 e^pi i (8 e^i pi)^(1/3) = 2 e^ipi/3 or 2 e^i(3pi/3) or 2e^i(5 pi/3) = 2(cos 60+ i sin 60) or = 2 (cos 180 + i sin 180) or = 2 (cos 300 + i sin 300) = 1 + 1.73 i or...
May 17, 2016

LIMITS CALCULUS
as x gets big the numerator is dominated by the -8 x^3 term as x gets big the denominator is dominated by the x^3 term so the numerator over the denominator ----> -8 x^3/x^3 = -8
May 17, 2016

physics
m = integral fro 0 to L of λ dx m= λo [ L + (1/3L^2)L^3 ] m= λo [ 4L/3 ] -------------------------------- Xcg = (1/m) λ x dx = (1/m) (x^4/4L^2 + x^2/2)λo = (1/m) (L^2)(3/4)λo = (3/4L)(3/4)L^2 = (9/16)L whew ------------------------------- for c ...
May 16, 2016

Maths
seventh term = sixth term * 3 eighth term = sixth term * 9 ninth term = sixth term * 27
May 16, 2016

calculus
hypotenuse = 2 adjacent = x so opposite = sqrt(4 - x^2) sin = sqrt(4-x^2) / 2
May 16, 2016

Math
Nah, when you multiply by 1.2 you do not get anything that big 6.3 * 1.2 = 7.56 one way to think about it: (6 + 0.3)(1 + 0.2) = 6(1 + 0.2) + 0.3(1 + 0.2) = 6 + 1.2 + 0.3 + .06 = 7.56
May 16, 2016

Physics
Just before he releases it it is doing nothing, zero.
May 16, 2016

Physics
KE at start = (1/2) m v^2 = PE at end = m g h = m g(10)(1-cos Theta)
May 16, 2016

Geometry
(2/5)^2 as I explained in the other problem
May 15, 2016

Geometry
for similar figures" lengths are proportional to scale ratio areas are proportional to the square of scale ration volumes are proportional to cube of scale ratio 448/28 = 16 sqrt 16 = 4 so four times all the length measurements
May 15, 2016

maths
You do not walk on a bearing but on a heading. Math texts are not written by navigators. Bearing is the direction from you to a object like a lighthouse. North distance = 50 cos 25 = 45.3 East distance = 50 sin 25 + 200 = 221 distance = sqrt(45.3^3+221^2)
May 15, 2016

physics
G Mearth /r^2 so at r = 2 Rearth or altitude = radius of earth
May 15, 2016

typo ?
Actually the solubility of NaCl is about 359 grams/Liter A liter of water is about a kilogram
May 14, 2016

physics
density water = 1000 kg/m^3 g = 9.81 m/s^2 Volume = V mass = rho V weight = rho (9.81) V = 9.81 rho V Buoyancy = .25 - .01 = .24 N so .24 = 1000 (9.81)V V = .0245 *10^-3 m^3 m = .25 N/9.81 = .0255 Kg rho = m/V = 1.04 * 10^3 = 1040 Kg/m^3 answer (a) new buoyancy = 800*.0245*10...
May 13, 2016

physics
I do not know. Questions: initial velocity of truck? do they stick together?
May 13, 2016

physics
A has a mass of 500,00 (I assume you mean 500,000) A moves east, positive direction B moved west, negative Initial momentum east = 500, 000 *34 - 350,000 * 42 = 170*10^5 - 147*10^5 = 23*10^5 that will be the final too final mass = 5+3.5 = 8.5*10^5 so 8.5*10^5 V = 23*10^5 V...
May 13, 2016

maths-help me sir damon
I guess you mean km/hour Musa ran for Tm hours at speed Vm James ran at speed (Vm+1) Both ran for time t 4 = (Vm+1) t = Vm t + t 3.75 = Vm t so 4 = 3.75 + t t = .25 hr = 15 minutes
May 13, 2016

6th grade math
5 (240/6)
May 13, 2016

6th grade math
Try them first. I am not sure I will be here but someone probably will be.
May 13, 2016

6th grade math
You are welcome.
May 13, 2016

6th grade math
It kind of looks that way :)
May 13, 2016

6th grade math
100 * 8/20 = 5*8 = 40%
May 13, 2016

physics
the change from 40 east to 64 west is 40+64 :)
May 13, 2016

physics
opposite directions 64 - (-40) = 64 + 40
May 13, 2016

physics
You are welcome.
May 13, 2016

physics
change of momentum = force * time .320 (40+64) = 755 t
May 13, 2016

math
4 7/8 = 39/8 24 3/8 = 195/8 195/39 = 5 Of course we have made no allowance for the saw kerf.
May 13, 2016

Algebra
m = -2/3 y at x = 0 is 1
May 13, 2016

Math
could you mean: (2/3)y + 4 = 12 or 2/(3y) + 4 = 12 or 2/(3y+4) = 12 or 2/[3(y+4)] = 12 ? without parentheses I do not have any idea.
May 13, 2016

Physics
friction force = -.5 m g = .5 (9.81) m = -4.9 m a = F/m = -4.9 m/s^2 average speed during stop = Vi/2 so 60 = (Vi/2)t 120 = Vi t Vi = 120/t 60 = Vi t - .5(4.9) t^2 60 = 120 - 2.45 t^2 t = 7 seconds Vi = 120/7 = 17.1 m/s
May 13, 2016

physics
north 15 + 10 cos 45 = 22.07 east 10 sin 45 = 7.07 magnitude = sqrt (22.07^2+7.07^2) tan compass angle = 7.07/22.07
May 13, 2016

Pre-Calc
well, I suspect that you can find the sum of the arithmetic sequence starting with 1 and ending at 299 with d = 1 then you need to find the sum of the arithmetic sequence 3 6 9 12 ....... 297 from 3 to 297 with d = 3 then subtract see: http://www.mathsisfun.com/algebra/...
May 13, 2016

Math
.6 = 2.666666667 x x = .225
May 13, 2016

Algebra
40 r + 12 (1.5 r) = 638 (why did you subtract, she earns more for those 12 hours) 58 r = 638 r = 11
May 12, 2016

Math, Algebra
81^3 = (9^2)^3 = 9^6 so 9^6(x+1) = 9^2(x-1) so 6 x + 6 = x - 1 5 x = -7 x =-5/7
May 12, 2016

algebra pls pls help
3 times 5 is 15 and 15+15 = 30 so try the second one (3a-5)((3a-5)
May 12, 2016

algebra pls pls help
try x(2x^2 +6) + 7(2x^2+6) (x+7)(2)(x^2+3) A
May 12, 2016

physics
d = (1/2) g t^2 how long to fall 90 cm = .9 m .9 = (1/2)(9.81) t^2 how long to fall 40 cm = .4 m .4 = (1/2)(9.81) t^2 subtract
May 12, 2016

PHYSICS
LOL - yes, just like the diagrams in the link Bob gave you !
May 11, 2016

PHYSICS
draw two rays from the tip of the five cm candle The first one goes in hits the center of the mirror, and pops out at that same angle from the centerline tan theta = 5/35 The second one oe twrd the mirror parallel to the center line and bounces off THROUGH the centerline 15 cm...
May 11, 2016

physics help pls
Tension in the cord = T a is up for mass 1, down for mass 2 mass 1 T - .2*9.81 = .2 * a mass 2 .4 * 9.81 - T = .4 a solve 2 T - .4*9.81 = .4 a -T + .4*9.81 = .4 a --------------------subtract 3 T =- .8*9.81 = 0 T = .8 * 9.81/3 go back and get a v = a t d = (1/2) a t^2
May 11, 2016

Physics
Assuming that it is off and not swinging in the wind it only has gravitational potential energy.
May 11, 2016

Algebra
Well, since you did nt read the chapter on parentheses I will have to guess a couple of possibilities. (1/2)(k-5) = 3 k - 5 = 6 k = 11 or maybe 1/[2(k-5)] = 3 1 = 6(k-5) 1 = 6 k - 30 6 k = 31 k = 31/6
May 10, 2016

Math
y = -3(6) + 8 so y = -18 + 8 from zero on your number line go left 18. Then go right 8. Where are you?
May 10, 2016

Science
a quantity that has both a magnitude (size which is a "scalar") and a direction. speed is a scalar (magnitude) velocity is a vector (speed AND direction) In a car You can measure speed with a speedometer BUT for velocity you also need a COMPASS
May 10, 2016

science
v = Vi + a t 0 = Vi -1.2 t 0 = Vi - 1.2*25 Vi = 1.2 * 25
May 10, 2016

Math
(84 + 92 + 84 + 74 + 70 + x)/6=84 84 + 92 + 84 + 74 + 70 + x = 6*84
May 9, 2016

Math
That should work. 3.99999..... 3 + 9/10 + 9/100 + 9/1000 ..... 3 + 9/10 3 + geometric sequence 3 + a + ar + ar^2 ... 3 + 9/10 + 9/10(1/10)etc a = 9/10 r = 1/10 sum = (9/10) (1/.9) so 3 + sum of infinite geometric series where a = .9 r = .1
May 9, 2016

Algebra
total speed of separation = 120 miles/hour 300 = 120 T T = 30/12 hours = 2 1/2 hours
May 8, 2016

also is it simple or compound interest?
Please elaborate.
May 8, 2016

where is your attempt?
My job is not to just do it for you but to help if you get stuck.
May 8, 2016

Calculus
x^2(3y^2dy) + 2x dx(y^3) - 2ydy +xdy + dx y = 0 dy (3x^2y^2-2y +x) +dx(2xy^3+y)=0 dy (3-2+1) + dx (2+1) = 0 2 dy = -3dx m = slope = dy/dx = -3/2 so y = -3/2 x + b 1 = -3/2 + b b = 5/2 so y = -3/2 x + 5/2 or 2 y = -3 x + 5
May 8, 2016

English
Post means after.
May 8, 2016

English
disagree with #7 answer disagree with #11, ante means "before"
May 8, 2016

science
http://sciencelearn.org.nz/Contexts/Light-and-Sight/Teaching-and-Learning-Approaches/Investigating-refraction-and-spearfishing
May 8, 2016

science
Google Snell's law. They always show that particular picture :) Perhaps google spear fishing as well in the second question, something with the same color and index of refraction does not bend or reflect or anything and is invisible.
May 8, 2016

calculus
if Q = 100 = 10^2 r = (1/3)10^-3*10^6 or (1/3)(10^3) + (1/2)10^-2*10^4 or (1/2)(10^2) + 10^1*10^2 = 10^3 + 10^2 = about 333+ 50 + 1000 + 100 or about 1483 I get
May 8, 2016

calculus
Oh my Have you done integration of polynomials? integral x^n dx = 1/(n+1)x^(n+1) so integral x^2 dx = (1/3)x^3
May 8, 2016

just integrate
r = (1/3)(.001)Q^3 + (1/2)(.01)Q^2 + 10 Q + 100
May 8, 2016

B
dx/dt = 500 dc/dx = 0 + 2 x dc/dt = dc/dx * dx/dt = 2 x * 500 so at x = 6000 dc/dt = 12,000 * 500
May 8, 2016

calculus
1 ∫ (1+3x)^.5 dx 0 let z = (1+3x) dz = 3 dx so dx = (1/3)dz if x = 0, z = 1 if x = 1, z = 4 so 4 ∫ (z)^.5 dz/3 1 is (1/4.5) z^1.5 at z = 4 - at z = 1
May 8, 2016

calculus
well, one way: let z = 3 + 2x then dz = 2 dx so dx = (1/2)dz if x = 0, z = 3 if x = 2, z = 7 so 7 ∫ (5/z)(1/2) dz 3
May 8, 2016

math
o cups orange g cups ginger f cups filler o + g + f = 400 120 </= o </= 400 0 </= g </= 80 f </= 280
May 8, 2016

math
58 = 8 x + 9 (7-x) 58 = 8 x - 9 x + 63 x = 5
May 8, 2016

math - hummm
That depends :( If you do not put the grape back, you only have 31 in the machine when you draw the mango. You assumed the two events were independent. They may not be. I would have said: 10/32 * 16/31 not 32
May 8, 2016

science
H2SO4 ???? 4*6*10^23 O atoms per mol so 8 * 6 * 10^23 in two mol = 48*10^23 = 4.8 * 10^24 quite a few
May 8, 2016

science
Huh ? do you mean The measured density of He at STP is 0.1784g/l.what is the weight of one mole? If so then 1 mole = 22.4 liters at STP 22.4 * .1784 = answer
May 8, 2016

science
a mol of O2 has mass of about 32 g/mol so 32 g/mol * 1 liter/1.429 g = (32/1.429) liters/mol I hope it is about 22.4 liters :)
May 8, 2016

physics
ah --- if the altitude of the kicking foot and the goalie hands is the same, then the kinetic energy is the same. same (1/2) m v^2 so same 16 m/s (ignoring air friction)
May 8, 2016

math
yes, true
May 8, 2016

Math
7-2 = 5 so (5/7)x = 14 x = 14 * 7/5 total amount he had so cost = (2/7)(14 * 7/5) = 28/5 = $5.60 ==============check 14*7/5 - 28/5 = 10(7/5) = 14 yes
May 8, 2016

physics
How long to fall 54 meters with no initial vertical velocity? h = (1/2) g t^2 54 = 4.9 t^2 t = sqrt (54/4.9) then 130 = u t so u = 130/t
May 8, 2016

science
west =(1/3)hour*80 + (1/10)hr* 30 * cos 45 north = (1/10)*30 * sin 45 distance = sqrt(north^2+west^2) displacement = distance at angle T north of west where tan T = north/west speed = distance/ (1/3+1/10) velocity = speed at angle T
May 7, 2016

calculus help
You better use wolfram. That is a serious mess. http://www.wolframalpha.com/input/?i=integrate+dx%2F%283x^3-5%29^3+ type in integrate dx/(3x^3-5)^3 and click on the equal sign.
May 7, 2016

Science
distance d from home to college total distance = 2 d time to college = d/20 time to get back = d/40 total time driving = d/20 + d/40 average speed = 2d/(d/20+d/40) = 80/(2+1) = 80/3 = about 27 km/h
May 7, 2016

Math
pi (3.5)^2 (40) = 28 * 22 * h
May 7, 2016

physics
F = m a
May 7, 2016

Math
x = (3 y + 1) 4(3y+1) + 5 y = 4 12 y + 4 + 5 y = 4 17 y = 0 y = 0 x = 3*0 + 1 = 1 (1,0)
May 6, 2016

Math
m multiple pointers s short responders m + s = 20 3 m + 8 s = 100
May 6, 2016

Geography can someone please help me NOT ms.sue
I passed sixth grade.
May 6, 2016

Geography can someone please help me NOT ms.sue
It is all there in the Google stuff, political, economic and well I am not sure about socially. I have never been very social.
May 6, 2016

Geography can someone please help me NOT ms.sue
They named a beer after him.
May 6, 2016

Geography can someone please help me NOT ms.sue
http://www.google.com/search?q=stamp+act+unfair&ie=utf-8&oe=utf-8 You have got to be kidding.
May 6, 2016

Geography can someone please help me NOT ms.sue
That grouchy one in Massachusetts.
May 6, 2016

MATH PLEASE HELP FAST
1. 8 - 3 is NOT 11 but 5 what is 7+4? about 11 ? what is 1 - 3 maybe -2 look for f^2 + 11 f - 2 Now you do them more carefully
May 6, 2016

Physics
volume of water displaced = .1034^3 = .0011055 m^3 times density of water which is about 1000 kg/m^3 =1.106 kg of water displaced Archimedes says we can float that much mass .150 + m = 1.106 m = .956 kg = 956 grams
May 5, 2016

Physics
Why would surface area have anything to do with it?
May 5, 2016

Physics
diameter has nothing to do with it. rho g h = 1000 kg/m^3 * 9.81 * 30.34 Pascals
May 5, 2016

trig, precalc, math, algebra, trigonometry
cos theta = adjacent/hypotenuse call adjacent side v call hypotenuse 1 then cos theta = v opposite side = sqrt(1^2 - v^2) tan theta = sqrt(1-v^2) /v
May 5, 2016

Physics
If x is horizontal, there is no x component of weight. If x is down the slope then assuming you really mean 76 kg it is 76 * 9.81 * sin 10
May 5, 2016

Algebra
n and 2n-1 n + 2n - 1 = 20 3 n = 21
May 5, 2016

Science
I agree
May 4, 2016

PHYSICS
You push them to make them faster increasing their momentum. However they can not go a lot faster so that increased momentum shows up as mass rather than velocity. m = mo/sqrt (1 -v^2/c^2) as v ---> c the mass gets huge approaching undefined.
May 4, 2016

Math
x and x+5 x(x+5) = 6 x^2 + 5 x - 6 = 0 (x-1)(x+6) = 0 x = 1 or -6 if x = 1 x+5 = 6 and if x = -6 x+5 = -1
May 4, 2016

Parametric Curve
LOL e is a horizontal line, y = 5 b is a parabola, do what I suggested.
May 4, 2016

Parametric Curve
Well, I suppose if you do not see it as is, you can do x and y for example in (a) y = 4t-2 x = t+1 so t = x-1 y=4(x-2) - 2 y = 4 x -10 dx/dt=dy/dt = 0 so constant speed (d) If you do no see it is a circle, do the same thing again y = (2t+1) cos t y^2 = (2t+1)^2 cos^2 t x^2 = (...
May 4, 2016

math nid this asap tyy
m g h = (1/2) m v^2 h = v^2/2g v the same v^2 = 2 g h 2 * 9 .8 * 2.35 = 2 * 1.6 * h h = 14.4 meters
May 4, 2016

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