Tuesday
September 2, 2014

Posts by Damon


Total # Posts: 18,220

Calculus
Tyler, if yu do not know how to use parentheses try to type it with lines like 1 -------- (3 t - 1) or something.
April 7, 2014

Physics
I am not going to look at this until I see some attempt by you to balance forces and moments.
April 7, 2014

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
April 7, 2014

World history
Netherlands ? :)
April 7, 2014

Math
2.7^3 = 19.683 15 * 19.683 = 295.245
April 6, 2014

statistics
by the way that calculator uses x - mean for z instead of (x-mean)/sigma
April 6, 2014

statistics
Here is an online normal distribution calculator: http://davidmlane.com/hyperstat/z_table.html
April 6, 2014

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 = ...
April 6, 2014

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 ...
April 6, 2014

Math
.5 = e^-k T ln .5 = - k T T = -.693/-k = .693/k b) T = .693 / .0001074 = 6454 years
April 6, 2014

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 :)
April 6, 2014

Physics
On earth I assume weight on first line = (86.4+20.8)(9.81) weight on second (lower) line = 20.8 (9.81)
April 6, 2014

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
April 6, 2014

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) ]
April 6, 2014

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
April 6, 2014

physics
z = 5 * 10^5 ohms i = 1/(5*`10^6) = .2 *10^-6 = 2 *10^-7
April 6, 2014

physics
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/rlcser.html
April 6, 2014

English
B. ok C. Based on his very frail appearance, a mugger might SURMISE that he would be SUSCEPTIBLE to a strong arm attack; however, that would be a great mistake.
April 5, 2014

English
My version A. I said that he was HYPOCRITICAL because he pretends to be filled with PIETY, but I know that he is a bigger sinner than I am. I wouldn't even mind that if on Sundays in church he wasn't so POMPOUS.
April 5, 2014

social studies check answers
1. disagree 2. no idea 4. agree
April 5, 2014

English
loud and intense manner.
April 5, 2014

algebra
.25 A = 48 A = 48/.25 = 48 * 4 = 192 (2/3) 192 = 2 (64) = 128
April 5, 2014

Read what you typed
Lots of dimensions missing.
April 5, 2014

Math
ds = sqrt (dx^2 + dy^2) dx = -5sin t +5 sin5t dx^2= 25sin^2 t -50sint sin5t+25sin^2 5t dy = 5 cos t -5 cos 5t dy^2= 25cos^2 t-50costcos5t +25 cos^2 5t luckily sin^2 + cos^2 = 1 dx^2+dy^2=50-50(sin t sin 5t+costcos 5t) but sin a sin b + cos a cos b = cos(a-b) = 50 - 50 cos 4 t...
April 5, 2014

Physics
delta L/L = (T/area) / E = (215*9.81 /2*10^-5) / 8*10^10 = ( 1054 * 10^5 ) / 8*10^10 = 132 * 10-5 so delta L = (3.5)(132*10^-5) = 461 * 10^-5 = .00461 meters = .461 cm
April 5, 2014

Physics
Tension in cable = T Force up at end from cable = T sin 37 compression Force toward wall = T cos 37 max friction force = .485 T cos 37 up vertical forces on rod sum to 0 2 Fg = .485 T cos 37 + T sin 37 2 Fg = .989 T T = 2.02 Fg take moments about intersection of rod and wall ...
April 5, 2014

Physics 141
Hey. I just did that.
April 5, 2014

Physics 141
Distance axle above step edge = .33 - .125 = .205 Angle T is angle between straight down from Axle and the top edge of the step so cos T = .205/.33 T = 10.58 deg sin T = .184 Take moments about the top edge of the step. F * .205 clockwise (my step is on the right) m g * .33 ...
April 5, 2014

Physics 141
T = 1/4 so f = 4
April 5, 2014

Physics 141
after one period T, (8 pi T) = 2 pi so T = 1/4 so f = 1/T = 4
April 5, 2014

math
first .2*9.45 = 1.89 remaining length = 9.45 - 1.89 = 7.56 so piece 2 + (piece 2 - .12) = 7.56 2 * piece 2 = 7.68 piece 2 = 3.84
April 5, 2014

Civil War
It did sort of.
April 5, 2014

strange question but
You can easily figure out the velocity of each. It has nothing to do with the mass. (1/2) m v^2 = m g h note m cancels v = sqrt (2gh) so for example for 2.5 meters v = sqrt (2* 9.81*2.5) = 7 meters/second -------------------------- The only force here is gravity itself F = m ...
April 5, 2014

physics
(1/2) L i^2 = (1/2) C V^2 i^2 = (C/L) V^2 i^2 = (3.1*10^-6 / 5.6*10^-3) (961) i^2 = 532 * 10^-3 = 53.2 * 10^-4 i = 7.3 * 10^-2 = .073 amps
April 5, 2014

physics
period = 1/frequency = (1/7.01)*10^-18 wavelength = 3*10^8 (1/7.01)*10^-18 = .428 * 19^-10 = 4.28 * 10^-11 meters
April 5, 2014

Statistics
I also agree
April 5, 2014

Pre calculus
if it is x^3 + 2 x^2 - 15 x + 20 = 0 then: http://www.mathportal.org/calculators/polynomials-solvers/polynomial-roots-calculator.php gives x = -5.44 x = 1.72 +/- .853 i
April 5, 2014

physics. PLEASE HELP
If it is 50 meters high, the pressure is the weight of a one meter square column 50 meters high. Water density is about 1000 Kilograms/ cubic meter So the mass of this column is 1000 Kg/m^3 * 50 m * g or 1000 * 50 * 9.81 = 490,500 Newtons that weight is spread out over the one...
April 4, 2014

Physics
work done = increase in kinetic energy (here we have a decrease so the work is negative. The force is opposite to the direction of motion) work = (1/2)(4.5*10^4)(5000^2 - 7000^2) work = force *distance moved in direction of force so Force = work/(1.4*10^6)
April 4, 2014

Physical science
k Q1 Q2 / d^2 1) if d2 = 3 d 1 then 1/d^2^2 = 1/(3d1)^2 = (1/9) 1/d1^2 2) k Q1 (2 Q2)/d^2 = twice original
April 4, 2014

speech-english
I am tempted to just say model right off the bat but it depends on the audience and the setting. If it is a big crowd in an auditorium a model might not be very easy to look at from all angles and see inside it. Then photographs or a flip chart might be better. If the ...
April 2, 2014

Physics
original east momentum = 2115*10.61 final east momentum = (2115+3169)*5.03cos32.4 22440 = 5284 * 4.25 v = 22440 v v =1 m/s
April 1, 2014

physics
not of the mass itself, but about some other point. For example for a point mass hanging from a nail on a string it is m L^2 about the attachment point at the ceiling where L is the length of the string.
April 1, 2014

Math (how do you find the volume of a cone)
for any object with a point at the top and straight sides use (1/3) height * area of base
April 1, 2014

Physics
r = 1.5 * 10^-3 m pi r^2 = pi (2.25) * 10^-6 m^2 F/A = P = 2*10^4 /[pi (2.25) *10^-6) ] = .283 *10^10 = 2.83 * 10*9 Pascals
April 1, 2014

Physics Help
You have: velocity v = dx/dt = -A*ω*sin(ωt) so what is -A omega ? A = 3.5 omega = 2 pi f = .848 so - A omega = -2.968 or -2.97
April 1, 2014

Geometry
http://www.jiskha.com/display.cgi?id=1396301143
March 31, 2014

Math probability
4+7+3+2 = 16 socks prob red first = 4/16 prob green second = 7/15 prob that happens = (4*7)/(16*15) prob green first = 7/16 prob red second = 4/15 so again (4*7)/(16*15) so in the end 2 * 4 * 7 / (15*16) = .233
March 31, 2014

Math
1/51 I just answered this a few minutes ago.
March 31, 2014

Geometry
equation of circle radius 25 : x^2 + y^2 = 25^2 = 625 now what is x when 15 cm from center (which is ten cm from surface)? x^2 + 225 = 625 x^2 = 400 x = 20 that is our radius at urface area = pi (20)^2 = 400 pi = 1257 cm^2
March 31, 2014

science(check answers)
2 was wrong as were the others I mentioned more mass ---> more pull of gravity
March 31, 2014

science(check answers)
1 A true If you pick a hunk of iron up you want to be able to drop it when you get it to the place you want it. 2 b F = G M1M2/d^2 force proportional to mass 6 c the resistance has to go up to keep the same current R = V/i 7 d i reverses, B reverses
March 31, 2014

math
.9 x = 22,000 x = 22,000/0.9 = 24,444,44
March 31, 2014

math
if the pool is 76 feet long and each tile is 6 feet you need 13 tiles because 12 tiles only goes 72 feet However do you not need other rows of tile? This is a very strange question. Most tiles are about 6 inches, not six feet and they are square and you have to fit them in ...
March 31, 2014

Math
They would have to go 1296 miles in 7 days. 1296/7 miles/day 1296 / (7*24)miles/hour
March 31, 2014

Math
10/510 = .0196
March 31, 2014

science(check answers)
1.D yes 2.A yes 3.A yes 4.im not sure please help V = i R 12 = 4 R , R = 12/4 = 3 Ohms 5.false. I agree but am not sure what it means. One could always have a short circuit where current streams through doing nothing useful.
March 31, 2014

Physics
weight down = m g max friction force = mu m g centripetal force = m (lateral acceleration) mu m g = m a = m (.96 g) a = .96 g We call "lateral acceleration" centripetal acceleration :)
March 31, 2014

Physics
2.1) LOL - I would guess around mu = 0.96 2.2) 120,000 m/h * 1 h/3600 s = 33.33 m/s m v^2/R = .96 m g R = v^2/(.96 g) = 118 meters 2.3) mu = .8*.96 = .768 Normal F = m g cos 15 = .966 m g friction force = mu Normal = .768*.966mg =.742 mg component of weight down slope = m g ...
March 31, 2014

Physical Sciences
Type Mach 2 into Google and get back 681 m/s Ac = v^2/r = (681)^2/5800 = 80 m/s^2 80/9.81 = 8.15 g
March 31, 2014

Calculus
LOL, sketch a graph !
March 31, 2014

Physics
You are welcome :)
March 31, 2014

Physics
ke of ball at bottom = (1/2) m (2.44)^2 = 2.98 m Pe at top = m g h = m (9.81)(h) so 9.81 h m = 2.98 m h = .303 meters h = 1.47 (1 - cos theta) .303/1.47 = 1 - cos T .206 = 1 - cos T -cos T = -.794 T = 37.4 degrees
March 31, 2014

physics
(1/2)(4.008) V^2 = (1/2)(2500)(.037)^2 V = .924 m/s .008 Vb = (4.008)(.924 ) Vb = 463 m/s
March 31, 2014

physics
use conservation of momentum to get the velocity of the total mass (4.008 kg) just after collision in terms of bullet velocity Vb. Call that V. (1/2) m V^2 = (1/2) k x^2 that gives you V go back and get Vb
March 31, 2014

Patterns and rules unit test 7th grade
geometric sequeence a = -2 r = 6 An = a r^(n-1) A5 = -2 (6)^4 = - 2592 A6 = 6(-2592) = - 15552 A7 = 6 A6 = -93312
March 31, 2014

Physics
weight in air = 6400 * 9.81 volume of water displaced = 1 m^3 weight of water displaced = 1000 *9.81 *1 = 9810 N = force up from water tension = (6400 - 1000)(9.81) = 52,974 N
March 31, 2014

Physics
(1/2) m v^2 = .5 * .559 * 2.7^2
March 31, 2014

statistics
first one 12/45 second on 11/44 12/45 * 11/44
March 31, 2014

physics
a) v^2/R b) m v^2/R
March 31, 2014

physics
2000 u = 10 (200 cos 60 ) u = cos 60
March 30, 2014

physics
1500 * 20 = (1500+m)10 m = 1500
March 30, 2014

physics
Because the air we live in also has pressure no pressure change in a horizontal hose with no flow through it.
March 30, 2014

physics
rho g h = 1000 (9.81)(30) = 2.94*10^5 add 1 atm = 1*10^5 and get total of 3.9 * 10^5
March 30, 2014

CALC 2
try similar for the rest
March 30, 2014

CALC 2
1 at start a eats 2/3 ** 1/9 *** 1/54 b eats 1/6 ** 1/36 ** 1/108 first line is geometric series 2/3 + 2/3(1/6) + (2/3)(1/6)^2 ... An = 2/3 +(1/6)^n-1 sum of that series = a/(1-r) = (2/3)/(1-1/6) = 2/3 /5/6 = 4/5
March 30, 2014

Physics
You understand that he used quite different numbers in his example, D = 2.71 diameter 24 liters instead of 25 1.1 instead of 1.4 min
March 30, 2014

Physics
I found it all right. He has a pretty convoluted way of explaining it but it is the same thing. I have no idea why he converted to cm^3 rather than to meters^3 from Liters 1000 Liters = 1 m^3 1 Liter = 1000 cm^3 1 m^3 = 1,000,000 cm^3 but it is standard to work in meters, kg ...
March 30, 2014

Statistic
You are welcome :)
March 30, 2014

Statistic
p(good) = .7 , p(fail) = .3 n = 10 crunch it out with your binomial distribution P(2) for example = C(10,2)*.7^2*.3^8 = 10!/[8!*2!] * .49 * 6.56*10^-5 = 45 * .49 * 6.56*10^-5 = .001447
March 30, 2014

physics
work done = change in Ke = (1/2) m v^2 = 500*900 Joules power = work/time = 500 * 900 / 5 = 90,000 Watts
March 30, 2014

math
2 * 3 = 3 * 2 ????? Commutative
March 30, 2014

Calculus Help Please
f(x) = f(a) + (x-a) f'(a) f(x) = x^4 df/dx = 4x^3 let a = 2 then f(a) = 2^4 = 16 f'(a) = 4*8 = 32 f(x) = 16 + (x-a)(32) x-a = - .001 so f(1.999) = 16 -.001(32) = 16 - .032 f(1.999) = 15.968 with calculator it is 15.968 also
March 30, 2014

Math (check answer)
if you mean absolute value of 7 yes it is 7
March 30, 2014

Calculus Help Please!!!
at x = 3 y = 3*3 - 9 = 0 at x = 2.4 y = 3(2.4) - 2.4^2 = 1.44 delta y = 1.44 -0 = 1.44 dy/dx = 3 - 2 x at x = 3 dy/dx = 3 - 6 = -3 if dx = -.6 dy = -3 (-.6) = 1.8
March 30, 2014

Algebra
.163 x = 47600 x = 47600/.163
March 30, 2014

Math
You are welcome :)
March 30, 2014

Math C redone
should subtract 30 (14*2+2), not 44 c) draw a Venn diagram Only in A1 = 103 - 30 = 73 Only in A2 = 992- 30= 962 Only in A3 = 10011 - 30 = 9981 shared = 3*14 + 2 = 44 sum = 11060
March 30, 2014

Math
a) just add them 11106 b) They are all in A3 so 10011 c) draw a Venn diagram Only in A1 = 103 - 44 = 59 Only in A2 = 992- 44= 948 Only in A3 = 10011 - 44 = 9967 shared = 3*14 + 2 = 44 sum = 11018
March 30, 2014

Math
do you mean y = 18/(x^2-9) ???? if so dy/dx = -18 (2x)/(x^2-9)^2 0 at x = 0 In that interval the bigger |x|. the more negative the function so it is max when x = 0 18/-9 = -2 so C
March 30, 2014

math
You are welcome, good luck.
March 30, 2014

math
25 * .65 = 16.25 25 * 0.65 * 0.2 = 3.25 but I do not believe that 0.2. I think you have the loss 80% when it should be like 20%
March 30, 2014

math
the cooking loss is 80% ??? that does not sound right but if you are serious then 25 * (1-.35) (.2)= 25*.65*.2 = 3.25 pounds
March 30, 2014

Algebra
x^2 + (2x+20)^2 = (2x+22)^2 x^2+ 4 x^2 + 80 x + 400 = 4 x^2+88x + 484 x^2 - 8 x - 84 = 0 (x-14)(x+6) = 0 x = 14 2x+20 = 48 2x+22 = 50
March 30, 2014

physic
Plus charges flow to one side, minus charges to the other.
March 30, 2014

Calculus Help Please!!!
Oh, I see f(x) = ln (1+x) df/dx = 1/(1+x) d^2f/dx^2 = -1/(1+x)^2 f(x) = f(0) + [1/(1+0)] x - x^2/2! ... f(x) = 0 + x - x^2/2 + ..... well at a first cut when is x^2/2 =.1 x? x/2 = .1 x = .2
March 30, 2014

Incomplete!
Linear approximation to what function? Did you try to copy and paste? If so, that does not work here.
March 30, 2014

Physic
zero The plus charges on one side exactly balance the - charges on the other side. If you for example had more plus charges on one plate then they would attract negative charges to the opposite plate and would cause a flow across. Moreover the entire capacitor would then have ...
March 30, 2014

Science
I do not understand what the second question means? Balance the equations or what?
March 30, 2014

Science
Al is +3 here 2 Al + 2CuCl2 --> 2AlCl3 + 3Cu
March 30, 2014

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