Thursday
July 24, 2014

Posts by Damon


Total # Posts: 17,501

Physic Moment of inertia
I = (2/5) m r^2 = (2/5)(11.1)(.630) = 2.8 kg m^2

Help!! Physics
c = speed of light = 3 * 10^8 m/s 199 = c T T =199/3*10^8 f = 1/T = 300* 10^6/199 = 1.51 * 10^6 Hz omega = 2 pi f = 9.47 * 10^6 omega^2 = 1/(LC) = 89.7*10^12 so C (785 * 10^-6) = (1/89.7) 10^-12 C = (1/70414) 10^-6 = 1.42 * 10^-5*10^-6 = 1.42 * 10-11

algebra
It represents the average speed during that interval or in other words the distance traveled during that interval/ 3 seconds d(5) = 16 * 25 = 400 d(2) = 16*4 = 64 distance during those three seconds = 400-64 = 336 feet 336 ft/3 s = 112 ft/s = average speed for that interval By...

Stats
easy to say they do not happen 1-pA = .6 1-pB = .5 so probability that neither happens is .3 so probability that at least one happens is 1-.3 = .7

maths natural log
Huh ? as t--> oo e^-anything t ----> 1/ e^big ---->0 so W ---> 0 and b ---> 800 What happened was that the black increased form their initial 50 to their final 800 while destroying the white populations, typical invasive species.

Stats
http://davidmlane.com/hyperstat/z_table.html

Stats
I can not see your graph. You can not copy and paste here, but find the area in that region

math
1000 * .90 * .90 = ?

Calculus
the rate of change of volume is the surface area times the rate of change of height 450 ft^3/min = surface area * dh/dt surface area = pi r^2 450 = pi (30^2) dh/dt dh/dt = .159 ft/min You could do this by saying V = pi r^2 h dV/dh = pi r^2 dV/dh*dh/dt = pi r^2 dh/dt chain rule...

math
you mean how many zeros I think look at b^2-4ac 49 -16*8 is NEGATIVE so two complex conjugate solutions, NO real solutions

math
find the zeros of that parabola, use the + one (I turned the parabola upside down because I like positive x^2 term) .06 x^2 - 9.6 x - 5.4 = 0 use x = [-b +/- sqrt(b^2-4ac) ]/2a while I use wolfram alpha http://www.wolframalpha.com/input/?i=+.06+x^2+-+9.6+x+-+5.4+%3D+0++ to get...

Physics
A) we pushed back on the snow Therefore Prof. Newton says (Law #3) that the snow pushes forward on us B) 410 forward - 187 backward = 223 N forward C) F = m a 223 = 530 (the driver evidently has no mass:) * a so a = 223/530 = .421 m/s^2 D) v = Vi + a t v = 0 + .421 (7.3) v = 3...

Science (check please)
Good, you are welcome :)

Science (check please)
agree

Math/precalc
Sorry tangent period is pi, not 2 pi so (2/3) x = 1 pi x = 3 pi/2 = period

Math/precalc
I do not think amplitude means much for a tangent function which goes to infinity twice a period so I would not say 3 but maybe undefined. when the x term increases to 2 pi from 0 we have gone a period so (2/3) x = 2 pi x = 3 pi when we have gone a period period = 3 pi

Pre calc
Oh, sorry, tangent repeats every pi, not 2 pi so period is 2 pi, not 4 pi

Pre calc
argument of tan = (x/2 + pi/8) when x = 0 right now argument of tan = (pi/8) what will x be when this is bigger by two pi? (x/2 + pi/8) = (2 pi + pi/8) or x/2 = 2 pi x = 4 pi = period or how much x has to increase to go a whole way around 2 pi radians

math
You are welcome:)

math
assume no calculus allowed thus complete he square to find the vertex of this parabola 16 t^2 - 20 t - 2 = -h 16 t^2 -20 t = - h + 2 t^2 - 5/4 t = - h/16 + 1/8 t^2- 5/4 t+ 25/64 = -h/16 + 8/64 + 25/64 (t - 5/8)^2 = -(1/16)(h - 33/4) so in 5/8 of a second it reaches the vertex ...

Physics
clockwise moments about support (ignoring g which cancels) (50 - 27) m - 27(.31) = 0 23 m = 8.37 m = 0.364

Math
4 x + 9 = 65 subtract 9 from both sides 4 x = 56 divide both sides by 4 x = 14

math
180 lbs/2.5 days = 72 lbs/day 72 lbs / day * 30 days = 2160 lbs about one ton, two half ton pickups full

math
It was in a steel box lined with layers and layers of bubble wrap ( one of the many ways my students use in the contest)

Calculus
so it is positive for x>.316 and for x <.316

Calculus
Note that you did the second derivative correctly. It is easier to write it their way y" = 10e^(-5x^2)(10x^2-1) It is zero at x = +/- .316

Calculus
first http://www.wolframalpha.com/input/?i=plot++e^%28-5x^2%29 Then this for second derivative and graph https://www.wolframalpha.com/input/?i=second+derivative+of+e^%28-5x^2%29

Calculus
first http://www.wolframalpha.com/input/?i=plot++e^%28-5x^2%29

Spanish needs Sra
Well, all I can say is I understand you and can follow the directions just fine, but I am no Spanish grammar expert so hope one comes along.

physics
mass 1 accelerates downward at a so mass 2 accelerates up at a tension = T mass 1: m g - T = m a so 3 g - T = 3 a mass 2: T - mg = m a so T = 2 (g+a) substitute T in mass 1 equation 3 g - 2(g+a) = 3 a g - 2 a = 3 a a = g/5 = 9.81/5 = 1.962 You could also use the total mass of ...

science (check please (:)
Wow, glad you chose the right answer :)

science (check please (:)
DO NOT USE BOTTLED WATER !!! 1. It is a waste of money 2. It fills the ocean with plastic bottle remains. That is once it gets thrown off the boats and bridges. 3. It burns up energy and resources for manufacture of bottles, distribution fuel etc etc anyway your answer is right.

science (check)
You are correct, but did you have to ask? :)

math help
for 5 days 2/5 + 1/5 + 3/5 = 6/5*5 = 30/5 Sat 3 *4/5 = 12/5 Wed -2/5 for wet Pepper 30/5 + 12/5 - 2/5 = 40/5 = 8 hours

math
http://www.jiskha.com/display.cgi?id=1396046268

science (check)
Yes, but the individuals may be fish or whatever.

Math for grade 6 peace
96 = 0.48 x x = 96/0.48

Physics
Take moment about the left end total mass = 20 + 14 + 39 = 73 kg That is force up from pivot (I am going to do force in kilograms because g will cancel everywhere.) pivot distance from left = 1.4 Distance left to 39 kg = x (our L is (x -1.4) ) moments about left end 14 * 0 - 7...

science
distance = speed * time same time, higher speed --> bigger distance

Math
x + 15 + 2x + 27 = 180 3 x = 138 x = 46

math help!!
[ (x^2+5x) - 6 ] [(x^2+5x) + 6 ] (x^2 + 5 x - 6) (x^2 + 5x + 6) now if the back of your book says (x^2 + 5 x + 6)( x^2 + 5 x - 6) That is the SAME

math help!!
You got the second one, just reversed x y = y x !

geometry
width of alley = 60 tan 40 so second building = 60 + 60 tan^2 40 =60 (1 + tan^2 40) = 110 ft

geometry
ratio of ANY lengths in similar figures is the same 12/16 = 3/4 2. Ratios of ANY areas is length ratio squared 9/16 3. 54 * 16/9 = 96

math help
That is exactly what we got x y = y x the order is just reversed

math help
LOL, no need for wolfram !

math help
remember - -d = + d

math help
[ (a-b) - (c-d) ] - [ (a-b) + (c-d) ] [ a - b - c + d ] [ a - b + c - d ]

Calculus Help Please!!!
One of us made an arithmetic mistake. It is up to Tanya to get it right :)

Calculus Help Please!!!
rate of change of temp proportional to temp above room temp which is 20 to make it easy on the arithmetic define T' = real T - 20 dT'/dt = k (T') dT/T' = k dt ln T' = k t T' = C e^kt let's call t = 0 at 1:30 T = 32.5 so T' = 12.5 12.5 = C e^0 = ...

Calculus Help Please!!!
I am going to assume it is algebra first take t = 0 at 1:30 T = Ti - k t Ti = 32.5 so T = 32.5 - k t 30.3 = 32.5 - k (1 hour) k = 2.2 so T = 32.5 - 2.2 t 37 = 32.5 - 2.2 t t = - 2.04 call it 2 hours so by that linear model 11:30 am now I will work on the more realistic calculu...

Calculus Help Please!!!
Are you sure this is calculus? You want exponential decay to room temp? Or is it algebra and you want a linear function?

math
Yes !!! You got it. even the -1 * -1 = + 1 part

math
sorry about the caps, was doing tax returns with caps lock on

math
yOU HAVE [X - [Y-Z) ] THAT IS [ X - Y - NEGATIVE Z ] - A NEGATIVE IS POSITIVE [ X -Y PLUS Z ]

math
x^2-(y - z)^2 exactly the same way let a = x let b = y-z now you have a^2-b^2 = (a-b)(a+b) so [x -(y-z) ] [ x + (y-z) ] (x-y+z)(x+y-z) you were close

math
let x = (a-b) let y = c then you have x^2 - y^2 = (x-y)(x+y) now put in (a-b) for x and put in c for y

physics
the only one that lacks serious damping is the light in a vacuum.

Chemistry URGENT
I see nothing wrong with them.

Chemistry URGENT
Oh, divide by 2 C6 H10 O5 + 6 O2 ---> 6CO2 + 5 H2O

Chemistry URGENT
C6 H10 O5 + O2 ---> CO2 + H2O we need an even number of O atoms 2 C6 H10 O5 + x O2 ---> 12CO2 + 10 H2O now O balance 10 + 2x = 24 + 10 x = 12 2 C6 H10 O5 + 12 O2 ---> 12CO2 + 10 H2O

MATH WORD PROBLEM
b+c = 420 so c = 420 - b c = (3/4) b so 3 b/4 = 420 - b 3 b = 1680 - 4 b 7 b = 1680 b = 240 bears total b = sb + bb but bb = (9/7)sb so 240 = sb +(9/7) sb = (16/7)sb sb = 105 small bears bb = 240 - 105 = 136 big bears I will leave the last part for you

Chemistry
2 * 7.9 = 15.8 mols C 15.8 * 12 g/mol = 189.6 grams of carbon

whoops
we got carbon as a result of step 2 so we could put it back in to step 1 then we would only need two carbons fo each CaCO3

Chemistry
In the end for the carbon 3 C --> CO + C + CaCO3 so in the end we need 3 C atoms for every molecule of CaCO3 C = 12 g Ca = 40 g 3O = 3*16 = 48 g so CaCO3 = 100 g/mol so we get 7.90 mols of CaCO3 for that we need 3*7.9 = 23.7 mols of C 23.7 * 12 = 284.4 grams of Carbon

WORD PROBLEMS UGH
kiwi need 336 * 6/8 = 252 fruits mango needs 336*3/5 = 202 fruits strawberries 336*5 = 1680 fruits total fruits = 2134

algebra
186 n + 30 ???? so what is the question?

Math please check my answer?
You are welcome :)

Math please check my answer?
By the way: https://www.wolframalpha.com/input/?i=e^%28x-4%29-2+

Math please check my answer?
again it has a horizontal asymptote of y = -2 as x--->-oo but is defined for all real x so yes, range is all real x

math
There is no sure answer since there is not a constant number of leaves per inch 2/3 = .67 leaves/inch 14/15 = .933 leaves /inch so 6 * .67 = 4.02 6 *.933 = 5.6 leaves per inch so probably more than four and less than 6 try 5 also see: http://www.jiskha.com/display.cgi?id=12608...

Math
yes, all real numbers again

Math
yes, all real numbers

Physics
well, I used 1000 for rho before I saw the hint so you use 1060 rho g h=1000*9.81*.496 = 4.86* 10^3 Pa which is 4.86 k Pa 15.02 - 4.86 = 10.15 k Pa rho g h = 1000*9.81*1.3 = 12.75 k Pa 15.02 + 12.75 = 27.8 k Pa

algebra
V = pi r^2 h = pi (D^2/4) H

Math
None of the functions you have listed seem to have zero denominators. This function has a horizontal asymptote at y = -1 as x --->-oo but is defined for all real x

physics
power = work/time = (25000+800)(30)/60 = 12,900 Watts or about 13 KW

Math
sign error add 37 x to both sides f(x) = 37 x + 82

Calculus
best use radians, pi/2

History
I think she quoted the Preamble to the Constitution.

physics
m1 = 40.4 x1 = 0.00 y1 = .403 m2 = 15.2 x2 = .158 y2 = 0.00 m3 = 9.49 x3 = 0.48 y3 = -.210 m = 65.09 kg x cg = [40.4*0+15.2*.158+9.49*.48]/65.09 = 0.107 m y cg =[40.4*.403+15.2*0+9.49*-.21]/65.09 = 0.22 m

physics
m=M/10^30 4.19*1.75 = m*(7.78-1.75) = m * 6.03 so m = 1.22 so m = 1.22 * 10^30 kg

Math ~ Check 1 Answer ~
You are welcome.

Math ~ Check 1 Answer ~
agree

math
a^2 + (a+1.05)^2 = 59^2 a^2 + a^2 + 2.1 a + 1.1025 = 3481 2 a^2 + 2.1 a = 3480 a^2 + 1.05 a - 1740 = 0 https://www.wolframalpha.com/input/?i=a^2+%2B+1.05+a+-+1740 a = 41.2 b = 42.2

physics
initial momentum = .00626*344 = 2.15 2.15 = .00626 Vb1 + 1.205*.673 Vb1 = 214 m/s exiting first block bullet momentum entering second = .00626*214 = 1.34 1.34 = 1.584 v v = .846 m/s (a) (b)final = (1/2)(1.584)(.846^2) = .567 Joules initial = (1/2)(.00626)(344)^2 =370 ratio = ....

physics
77.1 v = .0593 (.263) v = .000202 m/s better look fast because that blood circles around again in the body, reversing momentum :)

Social Studies
The way I read it: because accepting heliocentrism implied that the Bible was inaccurate since the Bible seems to support geocentrism

Social Studies
Agree about discontented citizens in France. steps?

Social Studies
The whole paragraph is about individual rights. It is not about tyranny of the majority,

World History
https://www.mtholyoke.edu/courses/rschwart/hist255/kat_anna/napoleon.html

World History
They wrecked the democracy. Napoleon just stepped in.

World History
No, D

World History
The Jacobins were world renowned radicals who turned the French revolution into chaos resulting in the Napoleonic wars and his rise to dictatorship and empire. https://www.mtholyoke.edu/courses/rschwart/hist255/kat_anna/jacobins.html

Algebra 1
s + (s+4) = 26 2 s + 4 = 26 2 s = 22 s = 11 which is luckily within our allowed domain :)

Physics
negligible :) F = G M1 M2 / d^2 F = 6.67 * 10^-11 * 443 * 356 /11.56 F = 91,000 *10^-11 = 9.1 *10^-7 Newtons

This is madness
I do the same question over and over. oh well s + (s+4) = 26 2 s + 4 = 26 2 s = 22 s = 11 which is luckily in our domain

physics
F = 9*10^9 Q1 Q2 /.16

math
Math - Damon, Thursday, March 27, 2014 at 11:57am A wrong .02 * .4 = .008 B wrong .03 * .4 = .012 C wrong .05 * .2 = .01 total wrong = .03 C wrong/total wrong = .01/.03 = .33

look below
I just did that

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