Tuesday

August 30, 2016
Total # Posts: 26,839

**simultaneous equation**

x^2+2xy-8y^2=0 (x+4y)(x-2y) = 0 so two routes to follow x = 2 y and x = -4y now the first one with x = 2 y 4 y^2 + y^2 - 4 y^2 = 21 y = +21 or - 21 then x = 42 or -42 so (42,21) (-42,-21) now the first one with x = -4y I will leave that for you
*April 8, 2016*

**physics- help me please**

pressure is weight per unit area the area at the bottom of the glass does not change however the mass of Hg is 13 times as much as that or the water therefore the pressure will be 13 times as big as P Hey, imagine the experiment !
*April 8, 2016*

**physics- help me please**

please look up the density of each. copper lead uranium then multiply by volume copper mass = copper density * 4 lead mass = lead density * 4 uranium mass = uranium density* 2 then list them in order
*April 8, 2016*

**PE**

You are welcome.
*April 8, 2016*

**PE**

http://www.jiskha.com/display.cgi?id=1460138784#1460138784.1460140028
*April 8, 2016*

**PE**

Look down to where I answered this.
*April 8, 2016*

**PE**

been there, did that scroll down
*April 8, 2016*

**Math**

Yikes, I did this a few minutes ago as well. 2
*April 8, 2016*

**Math**

How on earth would a bunch of retired teachers have the slightest idea what book you have or even what country you live in ?
*April 8, 2016*

**Math**

OIC
*April 8, 2016*

**Math**

The school? No way !!!
*April 8, 2016*

**Math**

v = pi r^2 h = pi (16)8 = 402 in^3 just two is 804 in^3
*April 8, 2016*

**P.E.**

2. disagree - http://www.google.com/search?q=central+nervous+system+components&ie=utf-8&oe=utf-8 3. agree 4. agree 5. agree
*April 8, 2016*

**c = 100 + 2 n**

Just in case you gave up :)
*April 8, 2016*

**ATTENTION TEACHERS AND STUDENTS**

c = f + n v or cost = fixed + variable * number that is a straight line with slope v and c intercept f 1100 = f + (500) v 1400 = f + (650) v --subtract---- ------------------- -300 = -150 v v = 2 then 100 = f so c = 100 + 2 n if n = 1000 c = 100 + 2000 = 2100
*April 8, 2016*

**Elementary education**

inside radius = 1 inch outside radius = 1.0625 inch volume = 1.25 (pi)(1.0625^2-1) = .5062 in^3 mass = 6 * .5062 = 3.04 oz
*April 8, 2016*

**Science**

.75 * 2.5 * 166
*April 8, 2016*

**Math**

vol of half sphere = (1/2)(4/3)pi r^3 vol of cone = (1/3)(5)(pi r^2) where r = 1.5
*April 8, 2016*

**Algebra 1-HELP!**

if x = 4 y = 6(4) - 1 y = 24 - 1 y = 23
*April 8, 2016*

**Math**

Yes, you are correct
*April 8, 2016*

**algebra**

(x^2-1) ------- (x+1) (x+1)(x-1) ----------- (x+1) = x-1
*April 8, 2016*

**Physics**

Oh all right I will do one more before getting grandkids up for school. dr/dt = (3.2+3.6t)i + (1.7-4.8t)j d^2r/dt^2 = 3.6 i - 4.8 j which is the acceleration, so what else is new? |a| = sqrt(3.6^2 + 4.8^2) tan angle north of east = -4.8/3.6 so angle South of East = 53.1 deg
*April 8, 2016*

**Physics**

oh well original velocity = 2.1 i + 0 j final velocity = Vx i + Vy j sqrt (Vx^2 + Vy^2) = 6.3 so Vx^2 + Vy^2 = 39.7 (Vx - 2.1)/3 = Ax (Vy - 0)/3 = Ay so Ay = Vy/3 Ax^2 + Ay^2 = 1.4^2 = 1.96 so three equations Ax^2 + Vy^2/9 = 1.96 Vx^2+Vy^2 = 39.7 Ax = (Vx - 2.1)/3
*April 8, 2016*

**chemistry**

4 mols HCl = 4 * (1+35.5) = 146 grams of HCl per liter so either mix a liter that way and pour out .2 liter or put .2*146 = 29.2 grams of HCl in .2 liter of water Of course that is easier said than done because how do you get 29.2 grams of the acid HCl ? It is not a solid that...
*April 8, 2016*

**Physics**

how long do you take? 90 = 8 t t = 11.25 seconds 8 = 1.20 v v = 6.67 m/s so 90 = 6.67 t t = 13.5 s so you should start 13.50 - 11.25 = 2.25 seconds after him
*April 8, 2016*

**Physics**

you went 15/60 * 13 = 3.25 miles in first 13 min so 26 - 3.25 = 22.75 miles left and 34 - 13 = 21 minutes left which is 21/60 = .35 hours so 22.75 miles/.35 hours = 65 mph
*April 8, 2016*

**math**

+ 24 * 20 = 2 * 240 = 480
*April 8, 2016*

**sorry, multiply by g**

need weight/area, not mass /area 600 * 9.81 = 5886 Pascals
*April 8, 2016*

**science**

That little piece of wood does NOT weigh 900 kg (maybe your car does) I think you mean 0.900 kg or 900 grams make its contact with the table as small as possible while not tipping over (standing on end) so area touching table is .05 * .03 = .0015 m^2 so p = force/area = 0.9/....
*April 8, 2016*

**Physics**

h = 40.2 + Vi t - 4.9 t^2 at ground h = 0 4.9 t^2 - Vi t - 40.2 = 0 but t = 4 so solve for Vi
*April 8, 2016*

**physics**

x = sin (2pi*741t) y = sin (2pi*715t) x+y= sin (2pi*741t)+sin(2pi*715t) but sin a + sin b= 2 sin.5(a+b)cos.5(a-b) so x+y =2 [sin average] cos half difference every max of the cosine, either + or - is a big noise so what you hear if they are close is the average frequency times...
*April 8, 2016*

**physics**

you hear the difference frequency 8 = 3580 - f f = 3472 original 12 = 3580 -f f = 3568 final good, the frequency went down when I loosened the string so 3568 Hz WHAT if I wrote the difference the other way (all I know is the absolute value) 8 = f - 3580 f = 3588 12 = f - 3580 ...
*April 8, 2016*

**Physics**

4.8 = u t what is t, the time airborne? 2 = 4.9 t^2 so t = sqrt(.408) = .639 second so u = 4.8/.639 = 7.51 m/s
*April 8, 2016*

**maths help me urgently!!!!!!**

i^2 = -1 1 - 2(-1) = 3 so this is 3/i multiply top and bottom by i 3 i/-1 or -3i
*April 7, 2016*

**physics**

omega = w = 2 pi f = sqrt(k/m) w = sqrt (222/.58) = 19.56 radians/sso x = .0335 sin 19.56 t v = .0335(19.56) cos 19.56 t a = -.0335(19.56)^2 sin 19.56 t = -19.56^2 x max v when cos 19.56 t = 1 and x = 0 so all energy is kinetic max v = .655 m/s (1/2) m v^2 = .125 J agree with ...
*April 7, 2016*

**Physics**

Initial momentum 390*20 - 500*8 = 3800 , x direction Final momentum = (390 + 500)v = 890 v , x direction But we all know from the first law deduced by Isaac Newton that since there are no external forces on this system in the x direction there will be no change in x momentum. ...
*April 7, 2016*

**Physics**

22*13.8 - 188 v = 0 v = 1.61 m/s
*April 7, 2016*

**maths**

23/3 = 7 2/3 so 8
*April 7, 2016*

**maths**

one man takes (6hr/7holes)5 men = 30/7 man hr per hole so 15/7 for half a hole
*April 7, 2016*

**maths**

I needed a common multiple of 2 and 3 that is 6 we are not doing fractions here, just integers
*April 7, 2016*

**maths**

a b c d d = 2 a b = 2 c a+d = 2 c ---------------------- a = 2 c - d = 2 c - 2 a so 3 a = 2 c hmmmm if c is 1, nope need common multiple for integer like 3 a = 6 2 c = 6 looks like a = 2 and c = 3 so far: 2 b 3 d but d = 2 a 2 b 3 4 b = 2 c so 2 6 3 4 2634
*April 7, 2016*

**calculus**

v = 5 t^-.5 = 5/sqrt(t) a = dv/dt = -2.5 t^-2.5 x = (5/.5)t^.5+c = 10 t^.5 + c 11 = 10 (1)^.5 + c c = 1 so x = 10 sqrt(t) + 1
*April 7, 2016*

**calculus**

a = -9.8 v = Vi - 9.8 t h = Hi + Vi t +(1/2) a t^2 h = 2300 + 0 t - 4.9 t^2 = 2300 - 4.9 t^2
*April 7, 2016*

**calculus**

v = vi - a t 0 = 7 - 9.8 t t = 7/9.8 at top when v = 0 h = 3 + 7 t - 4.9 t^2
*April 7, 2016*

**physics**

frequency proportional to sqrt(g/L) g proportional to mass of planet and 1/r^2 g planet = g earth * 1.75/6.25 = .28 sqrt gplanet = sqrt gearth =.529 so frequency is .529 tht on earth period = 1/f so 1.6/.529 = 3.02 seconds
*April 7, 2016*

**calculus**

d^2y/dx^2 = x^2 dy/dx = (1/3)x^3 + c 8 = 0 + c so c = 8 or dy/dx = (1/3)x^3 + 8 y = (1/12)x^4 + 8 x + k 8 = 0 + k so k = 8 y = (1/12)x^4 + 8 x + 8
*April 7, 2016*

**Pre cal**

b = 12 / sin 55
*April 7, 2016*

**Math**

He ran more last week If he ran 6 miles last week then he ran 5 miles this week the 25 2/3 is just noise on the circuit all that matters is the 5/6
*April 7, 2016*

**Math**

Now that is quite enough ! 5/6 is LESS than ONE
*April 7, 2016*

**physics**

x = A sin 2 pi f t x = A sin 12.9 t v = dx/dt = 12.9 A cos 12.9 t v = 1.9 = 12.9 A cos 0 = 12.9 A A = 1.90/12.9 = .147 meter
*April 7, 2016*

**English**

A traditional African marriage is advantageous for the man but not for the woman.
*April 7, 2016*

**Physics - urgent**

http://www.physicsclassroom.com/class/sound/Lesson-5/Closed-End-Air-Columns remember period T = wavelength/speed and f = 1/T = 350/wavelength here the lowest frequency is when .14 meter = half a wavelength so wavelength = .28 meter lowest f = 350/.28
*April 7, 2016*

**Pre cal**

49 + 16 = 65 so sqrt 65 which is about 8.062257748
*April 7, 2016*

**Science**

I did not bother to Google but your answers look correct to me.
*April 7, 2016*

**Physics**

The center of mass of the system continues at rest because there are no external forces on the system. cg at 0 forever m girl * distance from 0 = m plank * distance from 0 center of plank moves 3 to right if girl now 2 meters from CG of system to left 3*12.6 = 2 m m = 3 * 6.3...
*April 7, 2016*

**Physics**

I assume a short circuit so total voltage is 0 V = L di/dt + iR = 0 let i = I e^kt then when t =0, i = I di/dt = I k e^kt = k i V = L I k e^kt + I e^kt R = 0 L k + R = 0 k = -R/L but I bet you knew that so k = -130/50*10^-3 = -2.6*10^3 I = 12 so i = 12 e^-2.6*10^3 t 4.8/12 = ....
*April 7, 2016*

**Physics**

frequency is proportional to square root of tension f *sqrt (25) = 5 f
*April 7, 2016*

**Math**

it will be 1/8 times as large so small
*April 7, 2016*

**Math**

Evie, all your questions are the same if the numerator is bigger than the denominator, the fraction is bigger than one 4/3 is bigger than one so MORE
*April 7, 2016*

**math**

30 ft (1 m/5280 ft) = .00568 mile v = .00568 /T in hours T in hours = .00568 /v T in seconds = 3600*.00568/v = 20.45/v clicks/second = 1/T = v/20.45 so v = 20.45 * clicks/second 1 click/second --> 20.45 mph 2 clicks/second -->41 mph v = 20.45 * clicks/second = clicks/20....
*April 7, 2016*

**Math**

2/5 is less than 5/5
*April 7, 2016*

**Math**

(5/4)w * w = 180
*April 7, 2016*

**science**

total y momentum = 0 m * 1.5 sin 30 = m v sin T so v sin T = 0.75 total x momentum = 2 m 2 m = 1.5 m cos 30 + m v cos T v cos T = .7 v sin T/v cosT = tan T = .75/.7 T = 47 degrees v = .7/cos 47
*April 7, 2016*

**Math**

L = 14 w/13 (14 w/13)(w) = 4800 w^2 = 13 (4800/14) w = 66.76
*April 7, 2016*

**English**

yes
*April 7, 2016*

**Physics 1**

potential energy loss = m g h = 3.08 * 9.8 * 1.27 = kinetic energy gain = (1/2) (1.95)v^2 + (1/2)I (v/r)^2 so what is v at the end of this experiment? find acceleration 1.27 = (1/2)a t^2 1.27 = (1/2)a (.83)^2 so a = 3.69 m/s^2 and v = a t = 3.69(.83) = 3.06 m/s at the end...
*April 6, 2016*

**i need help plz**

You, anyone, can copy a bit of it for just about any purpose - parody, comment, review, .... whatever
*April 6, 2016*

**slope**

well, check it and see.
*April 6, 2016*

**slope**

well, we know it is y = -4 x + b so all we need is b 5 = -4(9) + b 5 = -36 + b b = 41 so y = -4 x + 41
*April 6, 2016*

**History**

It stood officially for slave stealer, but abolitionists called it "slave savior".
*April 6, 2016*

**History**

Yes, got sick while sneaking slaves out. Slaves could not navigate and boat was taken and Walker arrested etc.
*April 6, 2016*

**History**

We can not tell. Gibberish. Reed is telling you you probably listed answers to another question. I told you south is wrong for sure. I am wondering if you are paying attention.
*April 6, 2016*

**History**

I do not know what Brace is being compared to but he shipped kids more from New York area West so not mostly southern.
*April 6, 2016*

**College Algebra/pre-calculus**

agree
*April 6, 2016*

**physics**

Be sure to check my arithmetic carefully !
*April 6, 2016*

**physics**

v = 6.58 so omega = 11 radians/second
*April 6, 2016*

**physics**

fell distance 4.05 so lost potential energy m g h = 3 * 9.81 * 4.05 That is kinetic energy of bucket plus spool v = omega R = .6 omega call omega = w Ke = (1/2) m v^2 + (1/2)I w^2 = (1/2)v^2 (m + I/.36) I = 5 * .5 * .36 = so I/.36 = 2.5 so 3 * 9.81 * 4.05 = .5 * v^2 *(5.5) ...
*April 6, 2016*

**Physics miscounted**

134.4
*April 6, 2016*

**Physics**

C = Q/v = 40*10^-6 Q = 40 * 10^-6 v i = dQ/dt = 40*10^-6 dv/dt let v = V sin wt dV/dt = V w cos wt so i = 40*10^-6 V w cos w t max i = 40*10^-6 V w w = 2 pi f = 2 pi(60) = 377 so max i = 40*10^-6 * 377 V so V = (2.26/(15080)) 10^6 =1344
*April 6, 2016*

**Math help please**

YOU MEAN sin^2 x=[ 1-cos(2x) ] /2 or 2 sin^2 x = 1 - cos(2x) cos 2 x = cos^2 x - sin^2 x so 2 sin^2 x = 1 - cos^2 x + sin^2 x sin^2 x = 1 - cos^2 x or sin^2 x + cos^2 x = 1 which is true
*April 5, 2016*

**Physics**

620 * .39 = x * 1.53 so (.39/1.53)620
*April 4, 2016*

**Algebra**

maybe you want: 3 7 2 3,7 3,2 7,2
*April 4, 2016*

**English**

Either but I would pick 2 because in the end the person, not the food, is supposed to be healthy.
*April 4, 2016*

**Math**

log3 (3m) log a + log b = log ab That is how a slide rule works. That is how old I am :)
*April 4, 2016*

**PHYSICS!!!**

ke at bottom = (1/2) m v^2 = (1/2) m (144) = 72 m Joules pe at top = m g h= m (9.81)(12.2 sin 18 = 37 m Joules so Lost 72-37 = 35 m Joules to friction Friction force = mu m g cos 18= 9.33 mu m work done by friction = 9.33 mu m * 12.2 = 114 mu m so 35 m = 114 mu m mu = 35/114...
*April 4, 2016*

**PHYSICS!!!!**

10 km/hr = 10/3.6 = 2.78 m/s 3 km/hr = 3/3.6 = .833 m/s 5 km at 10 km/hr --> 30 min which is 30 *60 = 1800 s energy = 700*1800 = 1.26*10^6 Joules 5 km at 3 km/hr --> 6,000 s 6,000 s * 300 w = 1.8*10^6 Joules ==============================
*April 4, 2016*

**Physics**

assuming that your potential energy is defined as zero at the bottom of the hill, all your energy is kinetic by the time you get there. 800 + 200 = 1000 Pert of this problem statement is missing though. In potentials, all you can define is differences. You have to define some ...
*April 4, 2016*

**Math**

2 pi r = 2 pi *7 = 14 pi inches
*April 4, 2016*

**PHYSICS!!**

change in potential energy = m g h = 2219*4*sin 30 = 4438 Joules = (1/2)mv^2 + (1/2)I w^2 but w = v/r = v/.4 = 2.5 v so 4438 = (1/2)(226)v^2 + (1/2)(22.6)(6.25 v^2) or 4438 = 184 v^2 so v = 24.2 m/s and w = 60.4 radians/s Torque * angle = change in Ke T * 2 pi = (1/2) I w^2
*April 4, 2016*

**PHYSICS!!**

first mass of rubber = 2000 * .3 * ∫ 2 pi r dr from r = .2 to r = .4 = 600 (2 pi) (1/2)(.16-.04) = 226 kg 226 * 9.81 = 2219 Newtons weight I = 2000*.3 *∫ 2 pi r^3 dr = 3770 (1/4)(.4^4-.2^4) = 22.6 ===================
*April 4, 2016*

**PHYSICS!!**

time = 100 * 3600 = 3.6 * 10^5 s so energy used= 120*3.6*10^5 = 432 * 10^5 Joules = m g h = 65 * 9.81 * h so h = .677 * 10^5 = 67,700 meters
*April 4, 2016*

**Math**

but 24 inches = 2 feet so r = 1 foot (4/3) pi (1)^3 = 4.19 ft^3 by the way 4/3 x 3.14/1 = 1.395 is wrong --- should be 4.19
*April 4, 2016*

**Math**

3/4 = .75 3/8 = .375 which is bigger?
*April 4, 2016*

**Math**

2(3.14 x 0.25) + 2(3.14)(.5)(4) answer in feet^2
*April 4, 2016*

**no**

You have to use all feet or all inches r = 0.5 feet NOT 6 inches
*April 4, 2016*

**math**

s + (s+30) = 36 2 s = 6 s = 3 f = 33
*April 4, 2016*

**Math-soh cab toa**

sin 30 = h/70 but we all know sin 30 = 1/2 so 35
*April 4, 2016*

**Physics**

final angular momentum about axis of rotation = initial angular momentum initial ang mom = 78*1.6 * 2 = 250 kg m^2/s final ang mom = 78 (2)^2 omega + 651 omega omega ( 963) = 250 omega = .26 radians/second
*April 4, 2016*

**History**

I would have chosen B A ---- interchangeable parts, came before assembly lines for example in weapons manufacture (Colt in Connecticut for example)
*April 4, 2016*

**History**

I suppose I have to agree, but we lost our forests here in Massachusetts to farming and wood stoves long before we had woolen mills and Springfield rifles. The really tall pines of course were marked with broad arrow symbols and reserved for the king's masts.
*April 4, 2016*