Thursday

September 29, 2016
Total # Posts: 27,213

**Algebra**

L = 5 w - 1 A = L w = (5w-1)w A = 5 w^2 - w = 18 of whatever sl is 5 w - 1 w - 18 = 0 w = [ 1 +/- sqrt(1+360) ]/10 = [

*April 11, 2016*

**Math: Trigonometry**

cos^2 (2x-pi) = .75 cos (2x-pi) = +/-.866 let z = 2x-pi if z = 30 degrees (pi/3) yes if z = 150 degrees (2pi/3) yes if z = -30 degrees(-pi/3) yes if z = -150 degrees(-2pi/3) if z = -pi/3 then 2 x-pi =-pi/3 2 x = 2 pi/3 x = pi/3 , well that is + if z = +pi/3 2 x = pi + pi/3 = 4...

*April 10, 2016*

**Mathematics**

1 yes horizontal means both y vaues the same. -3 is not -8 vertical means both x values the same. 6 is not 0

*April 10, 2016*

**Physics**

I guess it is at constant velocity m g = 3.1*9.81 = 30.4 N weight mu m g = 43.5 N mu = 43.5/30.4 = 1.43

*April 10, 2016*

**PHYSICS!!**

original a momentum = 80*2.5 original b momentum = -68*1.2 total momentum before and after = 80*.5 - 68*1.2 after = 80*1 + 68 Vb which is final momentum a = 80 final momentum b = total - 80 F on a = (final momentum a - initial momentum a) /0.1

*April 10, 2016*

**Interest**

12,000 (1.056)^n

*April 10, 2016*

**Math**

You are welcome.

*April 10, 2016*

**Math**

(1/-9) /9 = -1/81

*April 10, 2016*

**Science**

http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html

*April 10, 2016*

**Science**

refraction occurs at a boundary where the speed of the wave changes. Google Snell's law

*April 10, 2016*

**stats**

cost = 500 + 200 + 200 = 900 revenue = 250 * 4 = 1000 obviously you can not raise 200 there are 1 + 2 + 4 = 7 winning tickets out of the 250 chance of winning 500 = 1/250 chance of winning 100 = 1/125 chance of winning 50 = 1/62.5 chance of winning anything at all = 7/250 ...

*April 10, 2016*

**Physics CENTER OF MASS**

http://www.jiskha.com/display.cgi?id=1460315436

*April 10, 2016*

**I did this already**

scroll down

*April 10, 2016*

**HELP PHYSICS!! WORK**

m g 8.3 sin 16 + friction force * 8.3 friction force = .6 (m g cos 16)

*April 10, 2016*

**Math ratio**

w/p = 3 or w in quarts = 3 * p in spoons 1 quart = 3* p in spoons for 1 qt so for 1 qt, p = 1/3 spoon for p = 1 spoon you get 3 quarts of water

*April 10, 2016*

**Calculus**

r^2 h = 21.66/pi = 6.89 now you still have to do the problem cost = cost of top and bottom + cost of side x is cost of side metal per in^2 C = 2x pi r^2 + x (2 pi r h) call c = C/2pix what we minimize c = r^2 + r h but we already know h = 6.89/r^2 c = r^2 + 6.89/r luckily you ...

*April 10, 2016*

**Multiplicative inverse**

if you go 10 miles per hour then that is indeed 1/10 hour per mile In general yes do not divide by zero though :)

*April 10, 2016*

**Math Grade 7**

1.5 = 3 times 1/2 3*8.5 = 25.5 minutes which luckily is less than 30 minutes

*April 10, 2016*

**Math**

4 - 3.981 = .019 but 4.001-4 = .001 so no, you are wrong

*April 10, 2016*

**Work**

no, if you push something to get it going you do positive work on it. Your force is in the direction of motion. I you were pushing a spring, it would do negative work on you. -(1/2)k x^2 :) but you would do positive work on it.

*April 10, 2016*

**Block Colliding with a Spring**

I will do more than you asked because I am sure there are more parts weight = m g = 1.6*9.81 = 15.7 N friction force = .48*15.7 = 7.53 N work done by friction = 7.53*.125 = .942 Joules work done by spring = (1/2)(480)(.125^2) = 3.75 J (ANSWER YOU ASKED FOR) total work done by ...

*April 10, 2016*

**Energy of satellite PHYSICS**

That is in Joules if you use m in kg G = 6.67*10^-11 N m^2/kg^2 Me = 5.98 * 10^24 kg Re = 6.38 * 10^6 meters

*April 10, 2016*

**Energy of satellite PHYSICS**

F = G m Me/(h+Re)^2 so let R = 2.3*10^7 + RE centripetal a = v^2/R so F = m a = m v^2/R = mG Me/R^2 or m v^2 = m G Me/R and .5 mv^2 = .5 m G Me/R

*April 10, 2016*

**Geometry**

Now do you know way the biggest rectangle area for 300 foot fence is a square? fence = 2 L + 2 w = 300 so L = 150 - w A = L W A = (150-w)w = 150 w - w^2 so w^2 -150 w = - A w^2 - 150 w + 75^2 = -A + 5625 vertex at w = 75 area = 5625

*April 10, 2016*

**Geometry**

fence length = 300 feet max is a square 300 = 4s s= 300/4 = 75 area = s^2 = 5625

*April 10, 2016*

**Geometry**

total area = (25+8)(12+8) water surface area = 25*12 = 300ft^2 subtract

*April 10, 2016*

**PHYSICS CENTER OF MASS**

.065 is the area of the plater with the hole removed

*April 10, 2016*

**PHYSICS CENTER OF MASS**

mass = 2.79(.23*.37-pi(.08)^2) = 2.79(.0851-.0201) = 2.79 * .065 = .181 kg agree moment in x (forget the 2.79 density) .065 x = .0851*.37/2 - .0201*.125 .065 x = .0157 - .0025 = .0125 x = .192 meter = 19.2 cm now do y of cm the same way

*April 10, 2016*

**Question**

New York is a State New York is a City New York is part of the Northeast region of the US

*April 10, 2016*

**Physics projectile**

constant = kinetic E + potential E = (1/2) m v^2 + m g h but v = Vi - g t so v^2 = Vi^2 - 2 Vi g t - g^2 t^2 so Ke = (1/2) m v^2 = .5m [ Vi^2 - 2 Vi g t - g^2 t^2] which is a parabola with vertex at (.5 m v^2) and dropping off with time

*April 10, 2016*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html

*April 10, 2016*

**Quick Physics help**

the rope the earth it is disturbed In your book, still 20 meters In real life due to the nonlinear behavior of shallow water waves, it will experience a net drift toward shore. 25 bounces / 5 seconds = 5 Hz

*April 10, 2016*

**Physics**

u = 30 cos 60 = 15 m/s so x = 15 * 4 = 60 meters away if we are interested now vertical Vi = 30 sin 60 = 26 m/s how far up in 4 seconds? h = Vi t - 4.9 t^2 = 26(4) - 4.9(16) = 104 - 78.4 = 25.6 I get, wonder if you use 4.9 for 9.81/2

*April 10, 2016*

**statistics**

why not?

*April 10, 2016*

**Physics**

here: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html NOW, that is the power PER UNIT AREA so 3.9 *10^26 / (4 pi r^2) = power per unit area = constant*T^4 as shown in Stefan/ B link

*April 10, 2016*

**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*