Friday
April 18, 2014

Posts by damon


Total # Posts: 16,151

Physics
2 cars pulling together on level surface? Mass of cars = 3800 kg weight of cars = 3800*9.81 = 37278 N so max friction force of tires = 37,278 N mass of full vault =38803 kg weight of full vault = 380,657 N max retarding friction = .57*380657 = 216,974 N In other words, based o...

History HELP! ASAP
Each of your questions requires an essay to help you and perhaps if you try to write them someone here can help with them. In this case I might concentrate on the interaction of England, France, US colonies and Iroquois and Algonquins. In the other question I would discuss rea...

science
m g h = Potential energy at top = 822 60 (9.81) h = 822 h = 1.4 meters

calculus help
https://www.wolframalpha.com/input/?i=derivative+of+x^2%28x%2B3%29%2F%28x%2B1%29^3 6x / (x+1)^4

calculus help
then do it again :)

calculus help
[(x+1)^2 (3 x^2)-x^3 (2)(x+1)] /(x+1)^4 [(x+1)(3x^2) - 2 x^3 ]/ (x+1)^3 [ 3 x^3 + 3 x^2 -2 x^3 ] / (x+1)^3 [ x^3 + 3 x^2] /(x+1)^3 x^2 (x+3) / (x+1)^3

calculus help
https://www.wolframalpha.com/input/?i=derivative+of+%28x^3%29%2F%28%28x%2B1%29^2%29+

Math
how many cups in a gallon? 16 so 2 cups concentrate + 16 cups water = 18 cups lemonade so concentrate / lemonade = 2/18 = 1/9 now how many ounces in a pint (a pint is a pound the world around :) 16 so 1/9 =x/16 x = 16/9 = 1.78 oz

SS
Build factories, farms, houses providing residents with jobs.

calculus help
Play with this: https://www.wolframalpha.com/input/?i=derivative+of+1%2B%281%2Fx%29%2B%285%2Fx^2%29%2B%281%2Fx^3%29+

Optics - sorry, not I
sorry, optics is not my thing at all :(

calculus help check and help
a) calculate lim t->infinity (v. answer: mg/c ----->what is the meaning of this limit ============================== It is the "terminal velocity" (Google that) which is the speed where the drag force equals the weight. One uses a parachute so that one's te...

physics
a = change in velocity/time = (0 - 43)/.28 = - 154 m/s^2

Geometry
for similar figures areas scale with the square of lengths so sqrt(4/49) = 2/7

math
1.025^10 = 1.280084544 * 5000 = 6400.42

calculus
http://www.mathsisfun.com/data/function-grapher.php f' = 7 e^7x - e^-x when is that zero? 7 e^7x = e^-x 7 e^8x = 1 e^8x = 1/7 8 x = ln(1/7) x = -.243 at min

calculus help
try : https://www.google.com/search?q=graph+ln%28x%29+from+1+to+6&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb ln 6 = 1.79 ln 1 = 0 ln 6 - ln 1 = 1.79 1.79/5 = .36 approx ln x = .36 e^ln x = ? = e^.36 so x = 1.43 sure enough between 1 and 6 :)

Algebra
2 (a+1) / [(a+1)(a-1)] for starters :)

Geometry- trig ratio
sin 55 = 21,000/hypotenuse we want that hypotenuse

science
you want traction, not slipping, so increase friction.

Math
sin 10 = PR/16 PR = 16 sin 10

Algebra
You are welcome. You could have done this by long division but often you can see the factors more quickly.

Algebra
2 x^3 – x^2 – 24 x + 12) = (2 x^3 -24 x) - (x^2 - 12) = 2 x (x^2-12) - 1 (x^2-12) = (2x-1)(x^2-12) now divide that by (2x-1) :)

Math
sin 10 = PR/16 PR = 16 sin 10

Math
1.05^2 - 1 = 10.25 APY Wilder 1.0081666^12 - 1 = 10.2524 APY Cheapskate so go with cheapskate ten years 1.05^20 =2.6532 *85,000 = 225,530.30 1.0008166667^120 = 2.65387 *85,000 = 225,579.18 Cheapskate is 48.88 better

english
The magnificent king emerged victorious eliciting a groan from his opponent who had been deserted by his muses depriving him of the strength of his convictions :-)>

Geometry - Area
You are welcome :)

Geometry - Area
find the area of each of the 6 equilateral triangles making up the hexagon Each side of triangle = 12 yards { by the way, first check apothem length because it is our altitude ) tan 30 = (1/2)(12)/apothem apothem = 6/tan 30 = 10.4 - sure enough, whew } so area of triangle = (1...

math
5 * .011 * p = 82.5

math
10 * .025 * 5000 5000 + part A (ignoring inflation :)

chemistry
Use google for conversion 1500 mm Hg = 1.97368421 atm = 199 983.553 pascals

Algebra II
In other words you did one of 120 sequences that yield 7 successes out of 10 trials.

Algebra II
....but the probability of failure is not independent of the probability of success :)

Algebra II
binomial distribution p(sucess) = 12/15 = 4/5 = .8 1-p = 1/5 = .2 n = 10 k = 7 P(x=7) = C(10,7) * .8^7 * .2^3 C(10,7) = 10!/[ 7! (3!) ] = 10*9*8 / (3*2) = 80*9/6 = 120 so P = (120)(.8^7)(.2^3) = 0.201

geometry
100 = 4x^2 25 = x^2 x = 5 or -5 but if you really want to use formula x^2 + 0 x - 25 = 0 x = [ -0 +/- sqrt (0 + 100) ] / 2 x = +/- 10/2 x = +/- 5

math (matrix)
I assume you meant the determinant 24 x + 3 x^2 + 6 x + 10 - 9x = 25 3 x^2 + 21 x -15 = 0 x^2 + 7 x - 5 = 0 x =-7/2 +/- (1/2) sqrt(69) What a mess, assume you have a typo. To invert matrix use http://matrix.reshish.com/inverse.php

math
100 * (1/8)/ (8/12+3/12) = 100 * (1/8) / (11/12) = 100 * (3/24)(22/24) = 100 (3/22) = 13.6%

Calc III
not a valid transformation, zeros on diagonal check with http://www.wolframalpha.com/widgets/view.jsp?id=d6a52679e750c30e320a7094ec975598

math
pi D = 3.14159 * 13

math
1" = 50 miles IS 2" = 100 miles so if 2" is only 25 miles, we will need four times as long a sheet of paper. so 4

whoops, arithmetic error
t^2 - 2 t - 3 = -(1/5)(h) t^2 - 2 t = -h/5 + 3 t^2 - 2 t + 1 = -h/5 + 4 (t-1)^2 = -(1/5) (h - 20) so max height at one second of 20 meters

Math 10
that is a parabola (quadratic) 5 t^2 - 10 t - 15 = -h find the vertex by completing the square t^2 - 2 t - 7.5 = -(1/5)(h) t^2 - 2 t = -h/5 + 7.5 t^2 - 2 t + 1 = -h/5 + 8.5 (t-1)^2 = -(1/5) (h - 42.5) so max height at one second of 42.5 meters

math
r = 24 in /gift * 1 yd / 36 in * number of gifts r = (24/36) * number of gifts cost = 2 * r

math
10 apples/basket 2 baskets/bushel so 20 apples per bushel min 900/20 = 90/2 = 45

math
number of cuts = (n-1) amount wasted = 1/16 * (n-1) amount total = (3/32) n + (1/16) n - 1/16 so 25 16/32 = 5 n/32 -2/32 816/32 +2/32 = 5 n/32 818 = 5 n n = 163.6 so 163

free-body diagram help
You only need the horizontal forces in this case because the friction force(not the coefficient) is given. 45 - 13 = 20 a work done = change in kinetic energy = (45 - 13) (4) Newton meters or Joules

Physics
weight of ladder = m g = W force down on floor = W max friction force = .3 W so horizontal force on top of ladder from wall = . W Take moments about base of ladder .3 W (L sin T) = W(L/2)cos T .3 sin T = (1/2) cos T tan T = .5/.3 T = 59 degrees Notice that the ladder length do...

maths
1.875 km * 2 * 6 = 22.5 km

Maths
3 a = 4 2 a = -3 there is only one variable here, a there is no intersection of lines so no solution by elimination or substitution: a = 4/3 for the first equation a = -3/2 for the second equation

Math
Very interesting but as far as I know these are your apparel dimensions. I do not read minds and have no idea what you are looking at. Is it a triangle maybe?

math PLEASE HELP!!!!!
girth = 2(32+49) = 162 times length 41 = 6642 ft^2 base area = 32*41 = 1312 times height = 64288 ft^3 Why on earth do you need a formula? Draw a picture.

Circle Geometry
draw a picture line from center of circle to tack hits circumference at a right angle (because it is a radius) and therefore that is the closest point to the tack. also line from circle center to ground is 90 deg so right triangle d is hypotenuse center to tack r^2 + 58^2 = d^...

Calculus Help Please!!!
Q = Qi e^-k t when Q/Qi = 1/2 .5 = e^-k t ln .5 = - 4 k so k = (ln .5) / -4 Q = 800 e^ (ln .5)t / 4 k = .1733 so Q = 800 e^-.1733 t if t = 30 Q = 800 e^-5.2 Q = 4.4 mg 1/800 = e^-.1733 t ln(1/800) = -.1733 t 38.6 days enough already

Physics multiple choice questions
Ah, first you try and it is too late because I have to go to sailing practice. Maybe Steve will help.

Calculus Help Please
ln x y = lnx + ln y ln x + ln y -cos^-1(x-1) = x 1/x + (1/y) dy/dx+(1/[1-(x-1)^2])^.5 = 1 1/x +(1/y)dy/dx+(1/(-x^2+2x)^.5) = 1 (1/y) dy/dx = 1 - 1/x - [1/(x(2-x))^.5 dy/dx = y { 1 - 1/x - [1/(x(2-x))^.5 } when x = 1 ln x + ln y -cos^-1(x-1) = x 0 + ln y - pi/2 = 1 ln y = 1 + p...

Physics
east is + 1500 * 25 - 2000 * 0 = 3500 v

Physics
change in momentum of car A = 1250 (40) = 50,000 toward the west so change in momentum of car B is 50,000 toward the east 50,000 = 2000 (east velocity - -25) 25 = east velocity + 25 east velocity = 0 stopped it dead in the water :)

physics
change in temp = 90 - 15 = 75 deg C heat in = mass * specific heat * change in temp = 12 kg * specific heat * 75 deg C I do not know specific heat in Joules or calories or kilocalories or whatever you are using in your class / kilogram deg C

college alg.
Different initial up speed but use : http://www.jiskha.com/display.cgi?id=1396965991#1396965991.1396967805

college algebra
h = hi + Vi t - (1/2) g t^2 in ancient English units this is h = Hi + Vi t - (1/2) 32 t^2 If Hi = 0 Vi = 128 ft/s then h = 128 t - 16 t^2 for h = 144 144 = 128 t - 16 t^2 16 t^2 - 128 t + 144 = 0 t^2 - 8 t + 9 = 0 t = [ 8 +/- sqrt(64 -36) ]/2 t = 4 +/- sqrt 7 t = 1.35 t = 6.65

Calculus Help
y = sin [ pi*(t^2+5)^-.5 ] y' = pi [cos pi*(t^2+5)^-.5] * [-.5(2t)](t^2+5)^-1.5 if t = 2 y' = pi {cos pi/ 3} *[-2] [ 1/27 ] = -(2pi/27) cos (pi/3) but cos pi/3 = 1/2 so -pi/27 CHECK MY ARITHMETIC !!!! =

Calculus Help Please!!!
sin 2 x ---- 2 x + .... as x -->0 tan x also ---> x so 2x /(2x - x) 2x/x = 2

Math
least common multiple 8 = 2*2*2 30 = 5*2*3 so we need a 5, 3 twos, and a 3 so 120

math word problem PLEASE HELP
r = ribbon = 15 (5 3/8) - 10(3/4) r = 15 (43/8) - 60/8 r = (15*43 - 60 )/8 = 585/8 = 73 1/8 yards

Physics
Or approximate in your head 1 atm = 10^5 Pascals approx so 2.38 atm = about 2.3 *10^5 pascals which is 2.3 * 10^2 kilopascals or 230

Physics
use Google type 2.38 atm = Pascal get 2.38 atm = 241 153.5 pascals which is 241 Kilopascals

Physic II
300 g = .3 kg so .3 * .11 * 5 thousand calories

chemistry
.75 * .5 = .375 mols of Na2CO3 2 HCl + Na2CO3 --> 2 NaCl + H2O +CO2 so we need .375 * 2 = .75 mols of HCl .75 * 1.25 = .9375 Liters

math
505200000000000 = 505,200,000,000,000 = 505.2 * 10^12 = 5.052 * 10^14 so YES :)

Fine number but what about it?
What is the question

Chemistry
Yes, but Mols of H2SO4 in ONE LITER 3 M means 3 mols in a liter 9 M means 9 mols in a Liter

Math
sin 2 x = sin x when x = 0, 180, 360 etc

science/math
1. No If it hits at 42 from the SURFACE that is 90-42 = 48 from the normal. The reflected ray will also be 48 from the normal. 2. NO 27 + 27 = 54

Physic II
sh in cal/kg deg C = .19 *1000 = 190 heat in = mass * sh * delta T 450,000 = 100 * 190 * (50-T) 23.68 = 50-T T = 26.3 deg C

physics
1) 90 - 42 2) 27 * 2

I already answered this
Please post once. Both are very wrong.

Math
You percent is percent that will FAIL It asks for the ones that do not fail.

Math
100 - 30.2

Math
Atta go :) You are welcome.

Math
dQ/dt = 200(-.0488) e^-.0488 t

Math
A = Ai e^-kt .5 = e^-14.2 k ln .5 = -14.2 k k = .0488 so Q = 200 e^-.0488 t

Math
Now I did problems very similar to this for you earlier. You try and I will check if I am around.

Math
You sure are having quite a time with these exponential functions! y = 190 [ 1- .955 e^-(.25 t) ] If t = 9 y = 190 [ 1 - .955(.105) ] = 190 [ 1 - .1 ] = 171 cm In other words it has reached 90% of max length in 9 years now dy/dt = 190(-.955) (-.25)(.105) = 4.76 cm/year c) when...

Physics
a) Vx = 65 cos 30, Vy = 65 sin 30 b) Vx =125 cos 40, Vy = -125 sin 40 c) Vx = 5.3 sin 30 , Vy = 5.3 cos 30 of course sin 30 = 1/2 and cos 30 = sqrt3/2

Calculus
Tyler, if yu do not know how to use parentheses try to type it with lines like 1 -------- (3 t - 1) or something.

Physics
I am not going to look at this until I see some attempt by you to balance forces and moments.

physics
Pick some time over which the dB/dt takes place, say t = one second. Then dB/dt = 3.2/1 = 3.2 T/s then you can get i for that dB/dt then i * t = i * one second

World history
Netherlands ? :)

Math
2.7^3 = 19.683 15 * 19.683 = 295.245

statistics
by the way that calculator uses x - mean for z instead of (x-mean)/sigma

statistics
Here is an online normal distribution calculator: http://davidmlane.com/hyperstat/z_table.html

statistics
well, you have enough data points to use normal distribution rather than computing with binomials forever and a day. Otherwise use a program or spreadsheet to compute all the binomial coefs and powers and products mean = n p = 200 * .6 = 120 sigma^2 = 120 (.4) = 48 so sigma = ...

Math
we have already done a half life one but anyway ds/dt = k s ds/s = k dt ln s = k t + c when t = 0, ln si = c si is initial size ln s = k t + ln si ln (s/si) = k t s/si = e^kt 2 = e^k(30 min) ln 2 = 30 k k = .0231 1,000,000/50 = e^.0231 t ln (20,000) = .0231 t t = 428.6 = 429 m...

Math
.5 = e^-k T ln .5 = - k T T = -.693/-k = .693/k b) T = .693 / .0001074 = 6454 years

physics
1 C 2 less, maybe you run over the mark from the first one on the track just as the rear can explodes, and the two marks on the track are together :)

Physics
On earth I assume weight on first line = (86.4+20.8)(9.81) weight on second (lower) line = 20.8 (9.81)

physics
in the horizontal direction the ball has no acceleration once let go (no horizontal force) so now it is 9 m/s^2 down by the way, g on Mars about the same as earth ? FALSE

physic
40 g = .04 kg .04 [25 (sh ice) + heat of fusion + 100 (sh water) + heat of vaporization + 5 (sh water vapor at 1 atm) ]

algebra 2
An = A1 + (n-1)d average = (A1 + An)/2 sum = average * number of terms = n (A1 +An)/2 = (n/2) [ 2 A1 + (n-1)d ] here = (11/2) [ -24 + (10)5 ] = (11/2) (26) = 11 * 13 = 143

physics
z = 5 * 10^5 ohms i = 1/(5*`10^6) = .2 *10^-6 = 2 *10^-7

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