# Posts by Damon

Total # Posts: 31,029

**Math**

small = s and b = big s = b-2 1/s + 2/b = 5/12 so 1/(b-2) + 2/b = 5/12 agreed multiply by 12 b (b-2) 12 b + 24(b-2) = 5 b(b-2) 12 b + 24 b - 48 = 5 b^2 - 10 b 0 = 5 b^2 - 46 b + 48 0 = (b-8)(5b-6) so use b = 8 s = b-2 = 6

**Physics**

normal force = m g max static = .75 m g so m a = .75 m g for slide to start or a = .75 g now the slide a = .75 g v = a t 33 = .75 g t t = 33/(.75*9.81)

**physics**

m g h = m g (3.4/2)

**Physics - Calculating work required**

This is a problem about POTENTIAL! The path does not matter ! That is the whole point. The voltage potential difference is the difference in potential energy of a unit charge at the two voltages. work done = charge * change in V

**Physics**

force = 55*9.81 Newtons pressure = force/area if area is in meters^2 then force is in Pascals

**physics**

Vi = 110,000 meters / 3600 seconds v = Vi + a t at end, v = 0 so 0 = Vi -49 t t = Vi/49 then d = Vi t + (1/2) a t^2 d = Vi (Vi/49) - (1/2)(49)(VI^2/49^2) d = (1/2)Vi^2/49

**Algebra**

I worked it out in the way you are probably used to. Scroll down

**Algebra**

44+47 = ? mi/h time = 69/speed

**Math**

divide by 1,000 kg/tonne

**arrgh upside down**

.3456/.84 = .4114

**too-hard probability sir damon/reiny/steve help**

He did, right here: P(w ? 0) = 1 - P(b = 4) = 1 - .4^4 P(b = 2) = 6 * .4^2 * .6^2 =============================== prob of some white = 1-.4^2 = .84 the prob of 2 black = 6*.4^2*.6^2 = .3456 divide .84/.3456 so

**too-hard probability sir damon/reiny/steve help**

LOL use Scott's answer. I used 10 for number of trials, did not read correctly.

**too-hard probability sir damon/reiny/steve help**

I got .121/.929 = 0.130

**too-hard probability sir damon/reiny/steve help**

well using C(n,r) for 2 black p(b) =.4 p(not black) = .6 n = 10 r = 2 P(10,2) = C(10,2) .4^2 .6^8 C(10,2) = 10!/[8! 2!] = 10*9/2 = 45 so 45 * .16 * .0168 =.121 now for no whites, that is P of 4 blacks 6/10 * 5/9 * 4/8 * 3/7 = .0714 1-.0714 = .929 = probability of at least one...

**Math HELP**

A is 3,4,5 so right B is right C 36 + 289 = 400 ?? I think not D 12.25 + 144 = 156.25? Yes, so right

**Typo**

rho = 2.04 kg/5.1*10^-4 m^3 = 4 * 10^3 kg/m^3

**Physics**

Please proof read what you wrote. It has got to be backwards. the density of the cube I suppose :) displaces water weighing 5 Newtons 5 N = 1000 kg/m^3 * 9.81 * Volume so Volume = 5.1* 10^-4 m^3 mass = 20 N in air I think/9.81 = 2.04 kg so rho = 2.04 kg/5.81*10^-4 m^3 = 3.51...

**Math question**

The volume of something pointy with straight sides is the base area times the height divided by three. V = (1/3) pi r^2 h = (1/3)(3.14) (1)^2 (9) = 9.42 in^3 to get the value multiply by 2 = $ 18.84 so I agree

**inverse correct - can not help with image**

For inverse check multiply |0 +6| |-1/2 1/4| |4 12| |+1/6 +0 | = 1 0 0 1 so right ! I have no idea what the image is about

**science**

What you are looking at is essentially an adiabatic expansion of the air as the pressure goes down (It does not gain or lose heat.) In an adiabatic expansion the temp goes down. http://en.wikipedia.org/wiki/Adiabatic_process

**science**

http://www.engineeringtoolbox.com/air-altitude-temperature-d_461.html

**science**

Do you know about Coriolis? One way to think about it: 1. say you have a low pressure spot in the northern hemisphere. 2. a parcel of air south of that spot will head north, toward the low pressure. 3. That parcel was moving east at the speed of the earth surface at that ...

**Math**

yes there are tricks to do these in your head like 15% is 10% + 5% 12.5 * 2 = 25 5% = (1/2) 10% etc

**Math**

(1/6)(1/2) = 1/12

**same question over and over and over**

delta L /L = k * delta T

**Math**

I you have two 25 degree angles in a triangle, the third one must be 130 degrees

**Math**

I guess you mean the two equal angles are each 25 since the sum must be 180 50 + x = 180 x = 130

**tecca math**

5,237

**huh?**

What do you mean? Are you missing parentheses or something?

**Logarithms**

x^log3(x) = 3^9 log3 (x^log3(x) = log3(x) log3(x) = 3^9 log3 (x) = 3^(9/2) = 3^4.5 = 140.3 3^log3(x) = x = 3^140.3 check my arithmetic, did quickly

**Logarithms**

2 log8 (8) - .5 ln (e) 2 - .5 = 1.5

**Logarithms**

log8 (5^8) - log8(7) = log8 (5^8/7)

**algebra**

yes

**algebra**

3x^2 - 5x + 2 = 0 a = 3 b = -5 c = +2 So I think the last one. if they ask for zeros (3x-2)(x-1) = 0 x = 2/3 or x = 1

**maths**

70*44*3 = 6 * pi (17.5)^2 t t = 70*44*3/[6*pi*17.5)^2] seconds divide by 3600 to get hours

**math**

train 1, x= 45*3 = 135, y = 0 dx/dt = 45 train 2, x = 0, y= -60*3 = -180 dy/dt = -60 z = hypotenuse z^2 = x^2+y^2 = 3^2 (45^2+60^2) = 3^2 (2025 + 3600) = 3^2(5625) so z = 3*75 = 225 z^2 = x^2 + y^2 2 z dz/dt = 2 x dx/dt +2 y dy/dt dz/dt = (xdx/t+ydy/dt)/z = (135*45-180*-60)/...

**algebra**

cos 75 = x/15

**maths**

L = 6 + 2 p W = 4 + 2 p 56 = (6+2p)(4+2p)-6*4 56 = 24 + 20p + 4p^2 -24 4 p^2 + 20 p - 56 = 0 p^2 + 5 p - 14 = 0 (p+7)(p-2) = 0 p = 2

**maths**

2 see above http://www.jiskha.com/display.cgi?id=1487067037

**Math**

4 b + 5 y = 49 2 b + 1 y = 17 4 b + 5 y = 49 10b + 5 y = 85 -----------------subtract -6 b = -36 b = 6

**Math 115**

6*1/2 = 3 while you rest 3 + (1/60 mile/min)(t-40)

**physics**

k Q1 Q2/ d^2

**Math**

to multiply by 100 while driving without a calculator: Stop the car by the side of the road. Move the decimal point two spaces to the right. Resume driving.

**Math**

42 animals 18-6 = 12 female cats prob of female cat = 12/42 now we have 41 animals, 11 females cats prob of female cat = 11/41 so 12/42 * 11/41

**Math**

-6x + 6 +3x = -3x + 6

**Math**

a + s = 220 7 a + 5.5 s = 1390

**Math/pre-algebra**

(.25 in / 6 ft) is our conversion factor 18 ft (.25 in/6 ft) = .75 in 66 (.25/6) = 11/4 204 (.25/6) =

**Needs Chemistry**

Not my thing, sorry

**Physical Science**

O has 8 protons and 8 neutrons. normally it has 8 electrons as well when it is neutral HOWEVER if it has a charge of +1 (unusual for O by the way) then it lost one of those 8 electrons and is left with 7

**calculus**

find y at the end (x = 10) find y at the beginning (x=3) subtract Yend - Ybegin divide that by 10-7 which is 3

**Physical Science**

You are welcome.

**Physical Science**

If it were A, it would be black :) If it were C, it would emit the transition spectra of the metal If it were D, yu would not see it at all :) So I think we pick B, which contains the handy word "reflect".

**physics**

during the stop, which starts at 20 and ends at 0, the average angular velocity is 10 rad/s 1 rev = 2pi rad 15.92 revs = 2*pi*15.92 rad so 2 pi * 15.92 rad/10 rad/s = about 10 s, yes I agree with teacher

**calculus**

I am a physicist so call your y "v", velocity and your x is "t" d = integral v dt d is integral from 1 to 5 of (t^2 -9) dt = t^3/3 - 9t at 5 - at 1 at 5 it is 125/3 - 45 at 1 it is 1/3 - 9 -------------------subtract 124/3 - 36

**Stat**

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

**physics**

forget cm, doing seconds and meters - SCI units Pe = (1/2) k |x|^2 Ke = (1/2) m |v|^2 so for Ke = 1/2 Pe m |v|^2 = .5 k |x|^2 but ?^2 = k/m so |v|^2 = .5 ?^2 |x|^2 At our spots [A ? cos ?t]^2 = .5?^2[A sin ?t]^2 A^2 ?^2 cos^2?t = .5?^2 A^2sin^2wt cos^2 ?t = .5 sin^2 ?t cos^2 ?...

**p**

I already did one like this for you.

**physics**

.35 meters in half a period, T/2 2 A = .35 x = A sin 2 pi f t x = A sin (2 pi t/T) max at T/4 min at 3T/4 3T/4 - T/4 = time between max and min = T/2 so 0.30 m/s = 0.35 m /(T/2)s T/2 = 0.35/.3 T = 7/3 seconds w = ang freq = 2pi/T = 6 pi/7 max a = w^2 A = (6pi/7)^2(.35/2) max v...

**physics**

I took this course in 1955 and no longer need practice. You are asking basically the same question over and over. I am happy to help but have done enough of them for you. since it is not extended at the start use y= A cos 2 pi t/T which is A at t = 0 and hits the lowest point...

**physics**

Hey, you do some now !

**Social Studies**

This is much more how I remember it: http://www.georgiaencyclopedia.org/articles/government-politics/worcester-v-georgia-1832

**Social Studies**

That decision I just looked up is not how I remember it in fact. I thought the Supreme Court sided with the tribes and Andrew Jackson kicked the tribes west anyway. Yes, what the above says is that white settlers can not be prohibited from trespassing on native property.

**Social Studies**

from Google: 515 (1832), was a case in which the United States Supreme Court vacated the conviction of Samuel Worcester and held that the Georgia criminal statute that prohibited non-Native Americans from being present on Native American lands without a license from the state ...

**physics**

sqrt (37^2+44^2) = 57.49 = 57 meters tan angle = 44/-37 angle = -50 x is - and y is + so second quadrant 180 - 50 = 130

**Geometry**

another one?

**Math**

e^0.018t = 20/12 .018 t = ln (20/12) = .511 t = 28.4 years

**physics**

ke = (1/2)(5.4) (6.2)^2 stops so all ke converted to U U = m g h = ke from first part 5.4 (9.81) h = answer from part 1

**physics**

d = (1/2) a t^2 8 = .5 a (16) so a = 1 m/s^2 v = a t = 1 (4) = 4 m/s or use head like this average speed = 8 m/4s = 2 m/s begin speed is zero so final speed = twice average speed = 2*2 = 4 m/s

**math algebra**

log x^n = n log x so you have log x (1+2+3+4 ...120) so log x times arithmetic sequence sum with a = 1, d = 1 n from 1 to 120 see http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

**Algebra**

|3y+4| means absolute value of 3y+4 -| means nothing to me.

**huh**

typo ?

**physics**

1 m^2 = 10,000 cm^2 20 * 10,000 = 200,000 N/m^2 400 cm^2 = 400/10,000 = .04 m^2 200,000 * .04 = 2000*4 = 8,000 N of weight about 800 kg mass if g = about 10m/s^2, small car :)

**math**

I said "which it is".

**math**

I suspect they mean every diameter of a circle is a chord, which it is.

**Math**

no 2 * 96 / .75 is not 640

**Ecconomics**

so you want the intersection? 15 - .2 p = -3 + .4 p .6 p = 18 p = 180/6 = 30 q = -3+12 = 9

**Math**

300 (1.00) - 300 (0.05) = 300 (0.95) = 285

**is it falling?**

if so then v = -gt d = -(1/2) g t^2 from second two to second three: d = -(1/2)g (9-4) = -(5/2) g from second three to second four: d = -(1/2)g (16-9) = -(7/2) g ratio = 7/5

**ed tech**

The software on this site does not allow copy and paste.

**ed tech**

You can not do that, sorry.

**Algebra**

diver 1 depth = 12 - 1 t diver 2 depth = 15 - 2 t so 12 - t = 15 - 2 t t = 15-12 t = 3 seconds 12 - t = 12 - 3 = 9 meters

**ART**

The only one I am familiar with is his painting of George Washington. That certainly is a formal soldier. This link is to another type of soldier but at least his head looks red: http://www.google.com/search?q=gilbert+stuart+painting+of+soldier+red+hair&tbm=isch&tbo=u&source=...

**projectile motion**

Nothing to do with the mass. I assume you mean 60 degrees from horizontal in which case the initial vertical velocity component is 5 sin 60 = 4.33 v = 4.33 - 9.81 t at top v = 0 so t = 4.33/9.81 = .441 seconds upward bound h = 4.33 t - 4.9 t^2 for range use 2 t (upward and ...

**Science**

two problems connected only by falling time vertical problem: Vi = initial y velocity = 0 v = Vi - g t h = Hi + Vi t - .5 g t^2 so at ground 0 = 0.6 + 0 - 4.9 t^2 t^2 = 0.6/4.9 t = 0.35 s to fall v at ground = 9.81* 0.35 horizontal velocity = 2.4 until it hits range = 2.4 * .35

**Algebra**

3 a + 9 c = 183 6 a + 13 c = 276 multiply first equation by 2 6 a + 18 c = 366 6 a + 13 c = 276 ---------------- subtract 5 c = 90 c = 18 etc

**Math**

32/8 1*8 = 8 2*8 = 16 3*8 = 24 4*8 = 32 5*8 = 40 6*8 = 48 7*8 = 56 8*8 = 64 9*8 = 72 10*8= 80

**English**

Is that chair related to you? Or is that the stairs groaning like your baby coyote?

**Science**

initial T = 0+273 P V= n R T same n and R so 2P * 2V = n R (4T) 4*273 = 1092 K which is 1092-273 = 819 C

**physics**

in Part A y = Vi t - 4.9 t^2 30 = Vi(2)- 4.9(4) 2 Vi = 49.6 Vi = 24.8 agreed Part B 15 = 24.8 t - 4.9 t^2 4.9 t^2 - 24.8 t + 15 = 0 t = [ 24.8 +/-sqrt(24.8^2-4*4.9*15) ]/9.81 =[24.8+/- 17.9]/9.81 use smaller t for on the way up .702 seconds

**physics**

I am not going to just do these for you in general magnitude = sqrt (xcomponent^2+ycomponent^2) tan angle from x axis = ycomponent/xcomponent) to do A + B say C = (Ax+Bx)i + (Ay+By)j where i and j are unit vectors in x and y directions

**Physiscs**

If it passes through the bar along the axis of the bar, the moment of inertia is small because the mass is close to the axis of rotation. Remember that mR^2 stuff. It is not zero though unless the radius of the bar is zero :) It is in fact a slender solid cylinder and its ...

**Physics**

Trace ray from the top of A and then another from the bottom of A

**Physics**

identical

**physics**

reaches top 3.6/2 or 1.8 seconds after launch at top, v = 0 but v = Vi - g t in meters, seconds g = 9.81 m/s^2 so 0 = Vi -9.81 t 0 = Vi -9.81*1.8 Vi = 17.7 meters/second

**math**

1.02 x = 7150 so x = 7150/1.02

**maths**

2*20 =

**pre calc**

top = L^2 bottom = L^2 4 sides = 4*13L total = 2 L^2 + 52 L

**algebra**

Good ! You are welcome.

**algebra**

no, look below carefully 3.2*10^2 LY ( 5.88*10^12 mi/LY) = 18.8 * 10^14 mi = 1.88 * 10^15 mi

**easy algebra question, check answer**

yes 3*10^1 * 3*10^5 = 9*10^6 because x^a * x^b = x^(a+b)