Saturday

May 28, 2016
Total # Posts: 26,283

**PHYSICS ENERGY CONSERVATION!!**

But, but, conservation is in your title !!!!
*April 10, 2016*

**PHYSICS ENERGY CONSERVATION!!**

at start E = (1/2) m v^2 + m g h E = (1/2)(395)(17.7)^2 + 395*9.81*7.2 = 61875 + 27900 = 89775 Joules at C 89775 = (1/2)395(7.6)^2+395*9.81*h h = [ 89775 - 11408] / (3875) h = 20.22 so agree but part b is trivial: 89775 is the total mechanical energy forever and ever by the ...
*April 10, 2016*

**factoring polynomiald**

8 b^2 + 6 b + 1 well 2+4 = 6 and 2*4 = 8 so (4b+1)(2b+1)
*April 10, 2016*

**Math**

L runs 3/5 mile/5 min = 3/25 mile/min 3 mile /3/25 mi/min = 25 min A runs7/10 / 5 = 7/50 mile/min 3 mile/ 7/50 = 150/7 = 21.4 min 25 - 21.4 = 3.6 min
*April 10, 2016*

**Math**

int (10t+1) dt = 5 t^2 + t at t = 0 that is 0 at t = x+3 that is 5(x+3)^2 +(x+3) subtract F(x) = - 5(x+3)^2 - x - 3 now do d/dx -10(x+3) - 1 or -10 x - 31
*April 10, 2016*

**science**

does pink have green?
*April 10, 2016*

**No such thing as acceleration in m/s **

-(20/3) m/s^2
*April 10, 2016*

**math**

draw the triangle
*April 10, 2016*

**science**

force = change of momentum/time = - m v /t force / area = force / given area by the way your units for first person's head area are wrong.
*April 10, 2016*

**math**

100 (80-60)/60
*April 10, 2016*

**physical science**

I guess net force includes gravity down so Force * time = change of momentum 6000 * 2.5 = 2000 (v-10)
*April 10, 2016*

**Precalculus**

AB = 6 AC = 8 all I need to know actually is AC = 8 so circumference = 8 (360/45) = 64 = 2 pi r r = 32/pi pi r^2 = pi (1024/pi^2) = 326 whatevers, miles, astronomical units, thumbs (I do physics not math)
*April 9, 2016*

**algebra**

20.5/11 = 2^n n log 2 = log 1.8636 n = .898 .898 * 6 hours = 5.39 hours
*April 9, 2016*

**Science**

F = k Q1 Q2/d^2 where k = 9 * 10^9 Q1 = Q2 = 1.6*10^-6 d = .028 meters = m g = 9.81 m
*April 9, 2016*

**cool**

Maybe there is an easier way, but that was fun !
*April 9, 2016*

**math**

log5 [ (3/5)(15^3/8) / (81/8)] well at least the 8 goes away easy log5 [ 3 *225 * 3 / 81 ] log5 [ 225/9 ] 2 log 5 (15/3) LOL !!! 2 log5 (5) 2 :)
*April 9, 2016*

**Physics**

first drop at top 0 = Vi - 9.81 t t = Vi/9.81 at top h = .55 = Vi t - 4.9 t^2 .55 = Vi^2/9.81 - 4.9(Vi^2/9.81^2) .55 = Vi^2/19.62 Vi = 3.28 m/s second drop at top .40 = Vi^2/19.62 Vi = 2.80 m/s a = (2.80 - 3.28)/time slowing down average Vi = (3.28+2.80)/2 = 3.04 m/s so time ...
*April 9, 2016*

**math, science, hindi, english, sst**

BM = MC = x which is half of BC angle AMB = T then angle AMC = 180 - T cos angle AMB = = cos T cos angle AMC = cos(180-T)=-cos T now law of cosines 4^2 = x^2 + 3^2 - 2(3x)cos T 8^2 = 3^2 + x^2 - 2(3x)(-cos T) 16 = x^2 + 9 - 6 x cos T 64 = x^2 + 9 + 6 x cos T...
*April 9, 2016*

**no, compounded**

if simple yearly interest intererst each year = .04 * 3000 = 120 120 * 10 = 1200 so 4200 would be correct BUT if compounded 3000(1.04)^10 = 3000*1.48 = 4440.73
*April 9, 2016*

**math**

times t hours and (t+2) hours) d1 = 50 t d2 = 40(t+2) 50 t = 10 + 40(t+2) 10 t = 90 t = 9
*April 9, 2016*

**math**

-2c/3 + 8 -30yz + 50 y
*April 9, 2016*

**math**

Plug and chug: numerator: f(2) = 4+3 = 7 g(7) = 3(7)- 2 = 19 f(19) = 38+3 = 41 denominator: g(2) = 6-2 = 4 f(4) = 8+3 = 11 f(11) = 22+3 = 25 so: 41/25
*April 9, 2016*

**Graphing Ciricles**

find the centers and radii x^2 - 10 x = -y^2 + 4 y +7 x^2 - 10 x + 25 = -y^2 + 4 y + 32 (x-5)^2 +y^2 -4 y + 4 = 36 (x-5)^2 + (y-4)^2 = 6^2 center at (5,4) r = 6 second one x^2 + 14 x +49 + y^2 + 6 y = 0 (x+7)^2 + y^2 + 6 y + 9 = 9 (x+7)^2 + (y+3)^2 = 3^2 center at (-7,-3), r...
*April 9, 2016*

**Graphing Quadratics**

zeros x = [-b +/- sqrt(b2-4ac)] /2a vertex therefore at x = -b/a 3 = -b/2a x intercepts are the same distance each side of 3 one is five to the left of 3 the other must be 5 to the right 3+5 = 8
*April 9, 2016*

**Math**

http://www.jiskha.com/display.cgi?id=1460217578
*April 9, 2016*

**I just did this**

check what I just answered.
*April 9, 2016*

**wrong**

(1+r)^t NOT (1+r)^2 except for two years 465,000 (1.06)^10 = 465,000 (1.79) = 832,744.18 now you do the rest
*April 9, 2016*

**Math/Algebra**

x = (3y-7)/(y+1) x + xy = 3y - 7 3 y - x y = x+7 y (3-x) = (x+7) y = -(x+7)/(x-3)
*April 9, 2016*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html
*April 9, 2016*

**Physics**

You kidding ? 1/4 = 1/2 * 1/2 so two half lives :)
*April 8, 2016*

**math**

huh, just multiply 20 * 12 * 8
*April 8, 2016*

**Physics**

I thought I did :) surely you can google E = m c^2 (Albert Einstein) there E is in Joules which is watt seconds c is speed of light, about 3*10^8 meters/second an hour is 3600 seconds a kilowatt is 1000 watts which is 1000 Joules/second
*April 8, 2016*

**Physics**

E = m c^2 c^2 = (3*10^8)^2 = 9 * 10^16 E = 5 * 10^15 watts * 3600 seconds = 18 * 10^18 Joules m = 18*10^18/9*10^16 = 2 * 10^2 = 200 Kg about two big people mass :)
*April 8, 2016*

**Physical Science**

agree y = A sin (2 pi f t) so A is half the distance from sin = -1 to sin = +1 or from sin = 0 to sin = 1
*April 8, 2016*

**check what I did**

lots of algebra here here is the integral site: http://www.wolframalpha.com/calculators/integral-calculator/
*April 8, 2016*

**Calculus**

radius of cylinder of skin thickness dr (r goes from 0 to 1) r = 1-cos x dr = sin x dx so circumference = 2 π (1-cos x) height of that cylinderical shell = x dV = 2 π(1-cos x) x dr = 2 π (1-cos x)x sin x dx = 2 π x sin x dx - 2 π x sin x cos x dx = 2...
*April 8, 2016*

**Science**

Now wait a minute, of course it is A. Think about air warming and rising and new air coming inward underneath and air coming from the south going east fast with the earth but the earth moving slower under it as it goes north because we are getting closer to the axis of ...
*April 8, 2016*

**Science Please help ASAP**

And by the way their leader is presently deep in that cheap hot water.
*April 8, 2016*

**Science Please help ASAP**

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiLx9md3f_LAhUGuxQKHTGJBuUQFggdMAA&url=http%3A%2F%2Fwww.theguardian.com%2Fenvironment%2F2008%2Fapr%2F22%2Frenewableenergy.alternativeenergy&usg=AFQjCNGuFFUv-l9dyXKYEDO1C2X-ku39nA&sig2=FM7A-...
*April 8, 2016*

**Science Please help ASAP**

You are welcome, and in Iceland they do not have to heat their hot water, just drill :)
*April 8, 2016*

**Science Please help ASAP**

Yes
*April 8, 2016*

**Science Please help ASAP**

Iceland :)
*April 8, 2016*

**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*