Monday

January 26, 2015

January 26, 2015

Total # Posts: 20,417

**Physics**

Try to draw a wavelength of .75 meters in your 1 meter string without a crest, not a node, at one end. D is allowed for sure, the lowest resonance. Draw it
*November 28, 2014*

**Calculus**

You are welcome.
*November 28, 2014*

**Calculus**

dy/dx = slope = 3 x^2 - 6 x + 5 where is that max or min ? where its derivative is 0 d^2y/dx^2 = 0 = 6 x - 6 so x = 1 is that a max or a min? take the ext derivative, if + it will be headed up and a min. d^3y/dx^3 = 6 that is positive so the min slope is at x = 1 that slope is...
*November 28, 2014*

**Math typo**

.... she walks 1 1/4 of an hour. Huh?
*November 28, 2014*

**Physics**

It only weighs about 270 N if 27 kg He is pulling with 454 N That is not right unless it is hooked to an anchor. It should probably be 270 kg for about 2700 N weight
*November 28, 2014*

**Physics**

Normal force on floor = m g - 454 sin 37 friction force = mu * normal force but friction force = 363 N you said so 363 = mu (27*9.8 - 454 sin 37)
*November 28, 2014*

**Physics**

ah, as happy as he ever got that is.
*November 28, 2014*

**Physics**

By the way I went to some pain to elaborate on this because a scientist named Edward Teller (Google him) asked me that very question in a slightly different manner when I was interviewing for a fellowship many years ago. I gave him the answer I just gave you and he was happy :)
*November 28, 2014*

**Physics**

It is very hard for a wave to change frequency. You have to store some of the waves somewhere if you do that because in the end the same number must enter one end of the box as come out the other. Think ocean waves coming into a beach, They slow down in the shallow water so ...
*November 28, 2014*

**physics**

Cut line, 2/3 and 1/3 Secure end of shorter line to tree. Reeve through block at car and secure to the hook on your second block which will be a traveling block Now secure the end of your longer line to the tree Run that line through the sheeve on the traveling block now look ...
*November 28, 2014*

**Physics**

(specific gravity of this oil*7 + 8)62.4 in pounds/ft^2 divide by 144 to get psi, pounds per square inch I do not know the ratio of this oil density to that of water
*November 28, 2014*

**Calculus**

How do we know h = 15 ? If we do not know h, then the solution is something that looks like a space needle :) L * w * h = 2160 if h = 15 L * w = 144 L = 144/w cost = c = 5(L*w) + 2 L*h + 2 w*h c = 5 L w + 2 w h + 2 L h if we know h = 15, then c = 5 L w + 30 w + 30 L c = 5*144...
*November 28, 2014*

**Math**

sin 63 = h/25
*November 28, 2014*

**Alg !**

http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
*November 28, 2014*

**whoops**

1 = 1/24 r^3 r^3 = 24 r = 2 sqrt 3 again can not be both
*November 28, 2014*

**math**

a r^2 = 9 a so r = 3 ar = (1/24) a r^4 r = (1/24) r^3 24 = r^2 but r = 3, can not be 3 and sqrt 24 a r^3 is fourth term 27 a = ? 48 ? a = 48/27 ? I think you have this messed up.
*November 28, 2014*

**math**

a ar^1 ar^2 ar^3 ----- ar^(n-1) ar^2 = 9a so a = 3 a r = (1/24) a r^4 r = (1/24) r^4 r^3 = 24 = 8*3 remember this so r = 2 *3^(1/3) fourth = a r^3 = 3 *24 = 72
*November 28, 2014*

**calculus**

a = -g = -9.8 m/s^2 The statement gives you the answer. v = integral a dt = -9.8 t + c at t = 0 v = Vi = 5 m/s so c = 5 v = -9.8 t + 5 h = integral v dt = 5 t -(9.8)/2 t^2 + cc when t = 0 h = Hi = 442 so cc = 442 h = 442 + 5 t - 4.9 t^2 (check your physics book :) at top, v = ...
*November 28, 2014*

**physics, how to find the height**

At max height all velocity is horizontal u = 26 but u = 65 cos Theta so Theta, the angle shot above horizontal = 66.4 deg so Vi = initial up speed = 65 sin Theta = 59.6 at top vertical speed = 0 so 0 = 59.6 - 9.8 t where t is rise time t = 6.08 seconds going up H = 0 + 59.6 t...
*November 27, 2014*

**physics**

Vi = 2.7 m/s h = 11 + 2.7 t = 4.9 t^2 0 = 11 + 2.7 t - 4.9 t^2 at ground 4.9 t^2 - 2.7 t - 11 = 0 t = [ 2.7 +/- sqt (2.7^2 +44*4.9) ]/9.8
*November 27, 2014*

**Math**

been there, done that http://www.jiskha.com/display.cgi?id=1417133335
*November 27, 2014*

**physics**

24 = (1/2)g t^2 48 = 9.8 t^2 t 2.21 seconds
*November 27, 2014*

**algebra**

.3 a + .8 b = .4 * 10 a + b = 10 .3 a + .8 b = 4 .8 a + .8 b = 8 ---------------- subtract -.5 a = - 4 a = 8 so b = 2
*November 27, 2014*

**Pre-Calc.**

LOL, but if two angles are 60 then so is the third and it is an equilateral triangle :) base = 24 12^2 + h^2 = 24^2 h^2 = -(3*4)^2 + (6 *4)^2 h^2 = 4^2 ( -9+36) = 4^2 (27) = 4^2*3^3 h = 4*3 * sqrt 3 h = 12 sqrt 3
*November 27, 2014*

**physics**

The mechanical energy of the system is the sum of kinetic and potential energy. In this ideal world it does not change with time. Since you found the maximum speed use (1/2) m v^2
*November 27, 2014*

**math**

a b c c = 2 a a + b + c = 14 a b 2a 3 a + b = 14 ones digit is even 1 b 2 ---> 3+b=14, b = 11 no 2 b 4 ----> 6 + b =14, b = 8 ok so 2 8 4
*November 27, 2014*

**math**

1 2 4 8 16 1 2^1 2^2 2^3 2^(n-1) a a2^1 a 2^2 .... geometric sequence with a = 1 r = 2 n = number of days 2^59 = area 2^x = 2^59/2 x = n-1 = 58 so 59 days which we could have said right off because if you cover the whole lake in 60 days then the day before you must have half ...
*November 27, 2014*

**algebra 2**

16 x^2 - 56 x = 0 x (16 x^2 - 56 ) = 0 x = 0 or x = 56/16
*November 27, 2014*

**math**

a ar^1 ar^2 ar^3 .... ar^(n-1) so a r^2 = 9 a a r^1 = (1/24)ar^4 ----------------------- ----------------------- so r = 3 a(3) = (1/24)a (3)^4 This is not possible. You have a typo.
*November 27, 2014*

**Math**

You are welcome.
*November 27, 2014*

**Math**

3/2 = L/b = 1.5/b 3 b = 3 b = 1
*November 27, 2014*

**Physics**

F = m a weight = m a a = -mg/m = - g in other words acceleration is down at -10 m/s^2 dv/dt = a = -10 so v = -10 t + c but at t = 0, v = +10 so c = 10 and v = -10 t + 10 now at the top, v = 0 0 = -10 t + 10 so at the top when t = 1 if v = -10 t + 10 then h = Hi + 10 t - 5 t^2 ...
*November 27, 2014*

**math**

I do not have a politically correct answer to your preamble question.
*November 27, 2014*

**math**

2 x + 3 y = 92 4 x - 7 y = 2 4 x + 6 y = 184 4 x - 7 y = 2 --------------------- 13 y = 182 y = 14 etc
*November 27, 2014*

**physics**

a quantity that has both magnitude and direction. for example you can measure the speed or magnitude of velocity of a car with a speedometer. However to specify the velocity vector you also need a compass. 20 km/hour is a scalar magnitude, speed 20 km/hour EAST is a vector.
*November 27, 2014*

**physics, how to find the height**

a = -g with g unknown at h = 0, Pe = 0 and Ke = (1/2)m Vi^2 = total energy at h = Htop , v = o and Pe = m g Htop = (1/2) m Vi^2 so Htop = Vi^2/2g at h = Htop/4 Pe = m g (Htop/4) = m Vi^2/8 total energy still = m Vi^2/2 so Ke = (3/4) (1/2)m Vi^2 so it still has (3/4) of initial...
*November 26, 2014*

**U.S. History Help!!!!!!!**

1 c I think (there were a lot of tories) 2 a 3 d
*November 26, 2014*

**Math**

.70 p = 72.09 p = 72.09/.7 = 102.99
*November 26, 2014*

**Language Arts**

I would pick B.
*November 26, 2014*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html
*November 26, 2014*

**six sigma**

http://davidmlane.com/hyperstat/z_table.html
*November 26, 2014*

**physics**

vertical problem Vi = 2390 sin 49.6 v = Vi - 9.8 t at top v = 0 so t = Vi/9.8 at top that is half the trip hits ground at tg = Vi/4.9 Now the horizontal problem u = 2390 sin 49.6 range = u tg range = 2390 sin 49.6 * Vi/4.9 so range = 2390^2 sin 49.6 cos49.6 /4.9 = 575369 ...
*November 26, 2014*

**math**

9/30 = 3/10
*November 26, 2014*

**Bus. Math**

s - .55 s = 5.12 .45 s = 5.12 s = 11.38 check 5.12 + .55(11.38) = 11.38
*November 26, 2014*

**math**

18+3 = 20 + 1 = 21 27 + 4 = 30 + 1 = 31 practice by drawing the problem on a number line.
*November 26, 2014*

**gen chem**

1/L = 10^7 (1/49 - 1/81) 1/L = 10^7( .00806 ) = .806* 10^4 L = 1.24 * 10^-4 meters
*November 26, 2014*

**MATHEMATICS**

Go back and read: 5 .55 That is a but you asked for term 6 which is a r^5 5.55 * 1.44^5 about 34.4
*November 26, 2014*

**Math**

.25 x = 3 x = 300/25 = 12
*November 26, 2014*

**Math**

.2 x = 80 x = 80/.2 = 800/2 = 400
*November 26, 2014*

**Chem**

Temp = 37 + 273 = 310 K P V = n R T V = .1 R (310)/92,000 but R = 8.315 Pascals m^3/mol K V = .1 * 8.315 * 310 /92,000 meters^3
*November 26, 2014*

**math**

(1)hypotenuse = straight home sqrt(36+64) = 10 straight is 10 miles same way is 6+8 = 14 miles (2) hypotenuse of 3,4 5 right triangle is 5 5*6 = 30 plus enough for the knots :) (3)diagonal (hypotenuse) length is the longest sqrt (42^2 + 84^2) = 93.9, so no
*November 26, 2014*

**Chem please help**

You do not need the s on https http://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/
*November 26, 2014*

**Chem please help**

or better: https://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/
*November 26, 2014*

**Chem please help**

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/helmholtz.html
*November 26, 2014*

**Math--1 question**

30 31 32 -- 33 -- 34 35 54 median clearly is 33 mean = sum /7 mode - no value occurs more than any other ranges from 30 to 54
*November 26, 2014*

**Coordinate Geometry (Algebra 1)**

First RS slope = (4 - -5) / (-8 - 4) = 9/-12 = -3/4 so it is y = -(3/4) x + b no need to find b, all we need is the slope -3/4 so slope of perpendicular = -1/m = +4/3 so 4/3 = (y-6) /( -3 - 0) 4/3 = (y-6)/-3 -4 = y-6 y = 2
*November 26, 2014*

**MATHEMATICS**

Been there, done that check below
*November 26, 2014*

**MATHAMATICS**

That is a but you asked for term 6 which is a r^5 5.55 * 1.44^5 about 34.4
*November 26, 2014*

**MATHAMATICS**

a ar ar^2 ar^3 etc a r^n-1 a r^4 = 24 a r^7 = 72 r^7/r^4 = 72/24 r^3 = 3 r = 3^(1/3) a 3^(4/3) = 24 a = 24 * 3^-(4/3) a = 5.55 r = 1.44 check a r^4 = 24.01 a r^7 = 72.04 ok
*November 26, 2014*

**physics**

initial momentum = 0 so final momentum = 0 0 = 80*1.5 + 120 * V V = - 120/120 = -1 meter/second
*November 26, 2014*

**math**

the first place on the right is either 0 or 1 times 2^0 which is one just as in base 10 the first place on the right is 0 1,2...9 or one of those numerals times 10^0 which is one the second place on the right is either 0 or 1 times 2^1 which is 2 just as in base 10 the second ...
*November 26, 2014*

**math**

1 * 2^0 = 1 0 * 2^1 = 0 1 * 2^2 = 4 1 * 2^3 = 8 so 13
*November 26, 2014*

**math**

1.25 L + .75 s = 109.75 L + s = 105 so s = (105-L) so 1.25 L + .75 (105-L) = 109.75
*November 26, 2014*

**Physics**

Force * distance/ time 85 * 9.8 * 2.5 Joules/second or Watts
*November 25, 2014*

**math**

7 * x^.5 * x^.5 = 7 * x^1 = 7 x
*November 25, 2014*

**chemistry**

H is enthalpy but I do physics, not chemistry.
*November 25, 2014*

**chemistry**

And I still think it is Physics :)
*November 25, 2014*

**chemistry**

(for example solids to gasses :)
*November 25, 2014*

**chemistry**

Increasing entropy is increasing disorder. look here http://chemistry.about.com/od/workedchemistryproblems/a/Entropy-Change-Example-Problem.htm note - more spread out --> more entropy
*November 25, 2014*

**physics**

350/353 = .991 seconds
*November 25, 2014*

**physics**

353 m/s
*November 25, 2014*

**physics**

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html
*November 25, 2014*

**physics**

No, you must look it up
*November 25, 2014*

**physics**

That sounds good. I did not look up the speed of sound at that temp.
*November 25, 2014*

**physics**

that is the frequency 1.3 kHz =1300 Hz period = 1/frequency
*November 25, 2014*

**physics**

You will have to look up the speed of sound in meters/s, somewhere around 350, at 35 C ,call it v distance = speed * time (a) t = 350/v (b) period = T = 1/f wavelength = speed * period lambda = v /1300
*November 25, 2014*

**Science 1 easy question!!!!**

Sure, fine. Of course I do not know the exact words your text used but suspect you got them there.
*November 25, 2014*

**Science 1 easy question!!!!**

yes, that will do.
*November 25, 2014*

**math**

pi (Rout^2 - Rin^2) = 8.68 In other words just hollow out the shaft.
*November 25, 2014*

**Science 1 easy question!!!!**

yes, those are ions, not sharing, giving and grabbing
*November 25, 2014*

**math**

https://www.mathsisfun.com/definitions/triangular-prism.html
*November 25, 2014*

**Physics help**

D is rather orderly and counter to increasing entropy by throwing them all around the room.
*November 25, 2014*

**Maths**

AB up y axis from (0,0) s to (0,s) then BC right s (s,s) then CD down s to (s,0) then DA left to (0,0) O at (x,y) a = -x i - y j b = -x i + (s-y) j c = (s-x)i (s-y) j unknown d = (s-x)i - y j c + a - b = (s-x)i +(s-y)j-y j -(s-y)j = (s-x)i - y j (Caramba) so I get d = c + a - b
*November 25, 2014*

**finance**

for normal curve calculations I use: http://davidmlane.com/hyperstat/z_table.html
*November 25, 2014*

**Chemistry**

100 * 3.46 / 3.67
*November 25, 2014*

**Chemistry**

http://www.jiskha.com/display.cgi?id=1416948226
*November 25, 2014*

**Chemistry**

did that a few minutes ago
*November 25, 2014*

**Thermodynamics**

dQ/T is negative for part of the cycle and positive for another. Of course if you include the surroundings overall entropy shows its usual tendency to increase :)
*November 25, 2014*

**Chemistry**

2Zn + O2 ---> 2 ZnO Zn = 65 O = 16 ZnO = 81 g/mol 2.8 g / 81 g/mol = .0346 mol ZnO half as many O2 mols = .0173 mol O2 .0173 * 32 g/mol = .553 mol O2
*November 25, 2014*

**programming**

n = 0 1 read x n = n + 1 print x If n > 1, go down to 2 small = x large = x 2 If x</= small, then small = x If x>/= large, then large = x If n < 12 , go back up to 1 Print small Print large end
*November 25, 2014*

**physics**

P V = n R T so P1 V1 = P2 V2 2374 V1 = 14.7 * 194
*November 25, 2014*

**Maths**

You are welcome.
*November 25, 2014*

**Maths**

5/6 = 175/g 5 g = 6 * 175 g = 6 * 175 / 5
*November 25, 2014*

**finnce100**

Maybe sell calls at a strike above the present price. Use that income to buy puts at a strike price lower than present price. That limits your future gains to the amount between present and call strike but gives you protection against a catastrophic fall.
*November 25, 2014*

**math**

-2 p + 2 q
*November 25, 2014*

**Chemistry**

{OH][H] = 10^-14 [H] = 10^-14/10^-3 = 10^-14 * 10^3 = 10^-11 strong base
*November 25, 2014*

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