# Posts by Damon

Total # Posts: 29,823

**Math**

maybe 1002001 ? That is a lot of km 2000 km / (35 + 48 + 45.5) = 15.56 km/L = 6.43 L/100 km

**physics**

http://www.physicsclassroom.com/class/sound/Lesson-5/Closed-End-Air-Columns

**Physics Force and Friction question**

max static friction force = .4*981 which is more than 350 so It stays in place. 350 N might be enough to keep it moving, but is not enough to start it.

**need more info**

Is it barely not moving, is it moving at constant velocity, is it accelerating?

**Math( 7th grade advanced math so 8th grade math)**

A = 3 x + 59 + 2*35 = 3x + 129

**physics**

oh my, still in feet? in this case g = about 32 ft/s^2 v = 58 - 32 t at top t = 0 t at top = 58/32 seconds total time in air by the way = 2 t = 58/16 seconds now the problem: h = Vi t - .5 * 32 t^2 H = 58 (58/32) - .5 * 58^2/32 (A.) H = 58^2/64 ft (B.) 2 t = 58/16 sec when h...

**Math( 7th grade advanced math so 8th grade math)**

ah 4 8 16 32 64

**Math( 7th grade advanced math so 8th grade math)**

4*2^n n = 4 quarters of and hour 2^4 = 16 so 4*16 = 64

**Science/Math**

If it did not float then 5 mL

**Math**

well, I am inclined to multiply first equation by 4 and second by 3 -56 x + 60 y = 12 +63 x - 60 y + 30 ------------------- add 7 x = 42 so x = 42/7 then -14(42/7) + 15 y = 3 -84 + 15 y = 3 15 y = 87 y = 87/15 ========================= try that in the second one to check 21(42...

**Social Studies**

Just for fun: http://www.nationalgeographic.com/travel/top-10/ancient-highways/ http://www.bbc.com/news/magazine-33291373

**Social Studies**

Did historical Japan have good roads? Did the Incas? How were each governed? How did they communicate with other nations?

**Math**

g = number of girls 5g/7 = number of boys g - 5g/7 = 120 2g/7 = 120 g/7 = 60 g = 420 then boys = (5/7)420 = 300 and 420 + 300 = 720 total

**chemistry**

Do you mean in catalytic converter? Maybe read "types" section in here: http://en.wikipedia.org/wiki/Catalytic_converter

**Math**

using common denominator of 18: 10/18 , 7/18 and 9/18 Now you rearrange them.

**physics**

2.9*9.81 Newtons

**chemistry**

A certain wavelength or frequency corresponds to a certain photon energy which is a certain change of energy of the electron shell around the atom. In other words the frequency tells you how an electron orbit changed.

**calculus**

dh/dt = -9.8 t + 10 when t = 1 dh/dt = 10-9.8 = 0.2

**math**

x y change in y/change in x which is slope -2 9 ****** -5 -1 4 ****** -5 0 -1 ****** -5 1 -6 ****** -5 2 -11 hmmm, constant slope = -5 y = -5 x + b 9 = -5 (-2) + b 9 = 10 + b b = -1 so y = -5 x -1 answer check at last point -11 = -5(2) -1 -11 = -10 - 1 yes, good

**Cousino**

speed upstream = 8 - u speed downstream = 8 + u time upstream = 5/(8-u) time downstream =5/(8+u) so 5(8-u) + 5/(8+u) = (4/3) hr 5(8+u) + 5(8-u) = (4/3)(64-u^2) 15(8+u) + 15(8-u) = 256(64-u^2) etc, solve quadratic

**be careful with parentherses**

do you mean 1/(2a) or (1/2)a 1) f(-2) = 4 a^2 +2a + 3b = 4 a^2-b+8 f(-3) = 9 a^2 +3a + 3b = 7a^2-b+14 so 2 a + 3 b = - b + 8 2 a + 4 b = 8 a + 2 b = 4 or a = 4 - 2 b and then 2 a^2 + 3 a + 4 b = 14 2(16 - 16 b +4b^2) + 3(4-2b) +4b=14 32 -32b +8b^2+12 -6b +4b = 14 30 + 8b^2 -...

**physics**

v = velocity up = 30 sin 30 - 9.81 t u = velocity horizontal = 30 cos t if t = 1 v = 15 - 9.81 u = 30(.866) speed = sqrt (u^2+v^2) tan angle up = v/u

**math**

as y--->0 cos y = 1 - y^2/2 + ........ numerator: 2 - 1 +(1/2)(9)x^2 -1 +(1/2)(16)x^2 0 + (25/2)x^2 oh my now divide by x 25 x/2 goes to 0 as x goes to 0

**math**

by the way tangent of small angle approaches sine of that small angle :) theta + theta^2/2 .......

**math**

Hey, I did the other one, try series approach on this one too.

**math**

m = math only s = science only b = both = 10 31 = m + b = m + 10 so m = 21 s+b = 36 - m s + 10 = 36 - 21 s + 10 = 15 so = Answer all science students s = 5 only science ======================== check 21 + 10 = 31, yes all math students 5 + 10 = 15 , yes all science students 21...

**Pre-calculus**

This is what it is about: http://www.youtube.com/watch?v=zw0waJCEc-w sin 45 = (1/2)sqrt 2

**Pre-calculus**

well, 7 = 6 + 1 so it is really sin (6 pi/12 + pi/12) sin(a+b) = sin a cos b + cos a sin b (just like your other problem) sin 6 pi/12 = sin 90 = 1 cos pi/12 = cos 15 deg cos 90 = 0 so cos 15 degrees

**Math**

y = k/x^3 new y = k/(x/2)^3 = 8 k/x^3 8 times as big

**english**

I have made 100 ship models in my life. I had made 100 ship models when they told me to stop and start doing physics problems.

**Maths**

9 km/(3/2)hr = 18/3 = 6 km/hr

**Math- Please check my answer!**

6/8 = 60/80 8/10 = 64/80

**Math**

2 driveways/day * 5 d/w = 10 driveways/week 10 driveways/week * 50 work weeks/yr = 500 driveways/year Now as Myah said, what is the question?

**physics**

heat of fusion * 150 g + 150 * heat capacity* (T-0) = 300 * heat capacity*(50-T)

**Physics**

normal forces 5 kg block: 5(9.81) 10 kg block 5*9.81 and 15*9.81 forces 5 kg block .2 * 5 * 9.81 right T left no acceleration so T = .2 * 5 * 9.81 = 9.81 N (answer to part C by the way) 10 kg block T left .1 * 15 * 9.81 left 45 N right so 45 - 9.81 - .1*15*9.81 = 10 a the end

**physics**

h = 1 = (1/2)(9.81)t^2 (a)solve that for t, the fall time u t = 1.5 (b)so u = 1.5/t v = g t = 9.81 t speed = sqrt (u^2+v^2) tan angle below hor = |v|/u

**8th Grade Math**

y = k x -12.5 = 50 k -25 = 100 k k = -1/4 y = -x/4 y = - (47/4) / 4 = - 47/16

**math**

(5)(3/13) - 2(10/13) = -5/13 You better stay away from this game. There are 13 cards in each suit of which 3, the jack, queen and king are winners. The other 10, ace through 10, are losers

**Physics**

If it is moving to the left, the frictional force is pushing right. 0.6 * 90 * 9.81 yes, looks about right but stick to 3 significant figures.

**algebra**

(0,13) (13,0) and (0,0) completes triangle that is half a 13 by 13 square area = 169/2

**environmental science**

Ah, almost but your understanding of feedback is backwards. Negative feedback means the output is fed back and inhibits further growth in the output, stable Positive feedback means the output is fed back and INCREASES growth in the output, UNSTABLE. This is what they are ...

**environmental science**

well, I guess natural gas is higher quality than most of what you find in a landfill :) It all depends on their definition of "near" the surface though.

**History**

LOL - yes, stamps and tea are different from each other.

**Physics**

total energy at top = (1/2)(1530)(36) + 1530(9.81)(115) total energy at bottom = (1/2)(1530)(27)^2 work done = energy at top - energy at bottom average velocity = (27+6)/2 time = 4400/average velocity power = work done/time

**Statistics**

binomial distribution p(n,k) = C(n,k)p^k (1-p)^(n-k) p(3,1) = C(3,3) .38^3 * .62^0 = 1 * .38^3 * 1 do c next because b is 1 - c p(3,0) = 1 * 1 * .68^3 now b = 1 - c = 1 - .68^3

**Science**

The word "compound" is a dead giveaway.

**Physics**

ice is about 2.03 Joules/ gram deg c so 2030 J/kg deg c 1.2 kg *2030 J /kg degC (-15-T) = 20,000 J

**Physics**

v cos 30 = 110

**Chemistry**

.37* 500 = .96 x where x is the amount of strong stuff you put in 500 - x is the amount of water

**Science**

which answer uses the word "compound"?

**Math. please help**

-1/2 = -3/6 +1/3 = 2/6 does that help ?

**Differential Calculus**

find radius of surface as a function of height h r/h = 5/10 = .5 then surface area = pi r^2 = pi (.25 h^2) change in volume dv = surface area * dh dv = pi (.25 h^2) dh and dv/dt = .25 pi h^2 dh/dt 4 = .25 pi (9) dh/dt solve for dh/dt

**algebra 1**

50 mi/h * 5280 ft/mi *1 h /3600 s mi cancels h cancels we are left with 50 * 5280/3600 ft/s = 73 ft/s

**error !**

french alone = f history alone = h both = 8 f+8 - 10 = h+8 or f-h = 10 and f+h + 8 = 40 or f+h = 32 so 2f =42 f = 21 h = 11 so f+8 = 29 study french or both h+8 = 19 study history or both

**Venn Diagram**

french alone = f history alone = h both = 8 f+8 - 10 = h+8 or f-h = 8 and f+h + 8 = 40 or f+h = 32 so 2f =40 f = 20 h = 12 so f+8 = 28 study french or both h+8 = 20 study history or both

**American Governement**

I would be inclined to favor A, balance of power.

**American Governement**

Yes, right, A

**Chemistry**

.12 * 207 grams

**value**

(1/2)(100)(64) Joules

**Chemistry**

LOL, not observable I am sure h/(mv) = 6*10^-34 / (.05*40)

**Math**

Two problems: 1. x-8 -15 = -6 2. -x+8 -15 = -6

**algebra**

3000 = 1000 e^10 k 3 = e^10k ln 3 = 10 k solve for k n = 1000 e^5k with same k do e^5k on your calculator

**social studies**

They are in it !!!

**Math/ Algebra**

I did not miss a sign. 1/3x is not x/3

**Math/ Algebra**

well, if it is actually 14 = (1/3) x + 5 or 14 = (x/3)+ 5 then that is 14 = (1/3)27 + 5 14 = 9 + 5 yes however 14 is not 1/ (3*27) + 5

**Math**

m marbles in bag 2m/5 are red so 3 m/5 = b+y m = r + b + y b/y = 5/7 or y = 7b/5 3 m/5 = b + 7b/5 3 m/5 = 12 b/5 4 b = m b = (1/4) m

**physics**

I gave you the frequency and the rotational speed because I do not know what "rotational frequency" means.

**physics**

v^2/r = 6 m/s^2 so v^2 = 86.5 *6 v = sqrt (86.5*6) T = pi d /v = pi(173)/sqrt(86.5*6) f = frequency = 1/T omega = 2 pi f = 2 pi/T = 2 sqrt(86.5*6) / 173

**Science**

no F = m a big F is big m times big a

**TECH ED HELP**

I agree with kara.

**Math**

agreed on the first 2, there is no answer for number 2 but the third 2y = 2x-6 y = x-3 slope = 1 your -3 is b in y = m x + b, the y axis intercept

**Calc I (@Reiny)**

Reiny already did this for you. Yes, right.

**physics**

vertical force = m g - F sin 38 horizontal force =.42*vertical force - F cos 38 when the horizontal force is zero, it is about to accelerate so when F cos 38 = .42 (85*9.81-F sin 38) solve for F

**math**

3/24 = 1/8 = .125

**Statistics**

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

**ashworth**

Google subjunctive of was: http://www.google.com/search?q=subjunctive+of+was&ie=utf-8&oe=utf-8 he approves not we approve

**computer**

LOL, this depends on the level of detail. I am not going to do an entire flow chart for Turbotax deluxe :)

**chemistry**

to raise the temperature of 1 kg of Aluminum one degree centigrade you must put in 900 Joules of heat energy.

**math(Quantitative) ...Pls help me**

(b) maybe time of year, exchange rate for currency

**math(Quantitative) ...Pls help me**

well, your guess is as good as mine but (a) number of football games, depth of snow (b) Legon Ghana? (c) number of hurricanes in past 12 months, number of arrests of bank officers (d) month of the year, number of weddings scheduled for week

**Maths**

(1/2) g/cm^3 or 500 kg/m^3

**chemistry**

http://www.google.com/search?q=ch3oh+lewis+structure&ie=utf-8&oe=utf-8

**math**

pi/2 3 pi/2 and I suppose -pi/2 -3 pi/2

**math**

so she buys all red ribbon ! 20/1.59

**Physics**

zero, it came back

**physic**

.5 (840)(T-16) = 2(4200)(25-T)

**Physics**

zero Displacement is a VECTOR this ball moved up, then down. It therefore moved zero meters in no direction. They did NOT ask for DISTANCE

**Math**

C(16,4) = 16! / [ (16-4)!(4!) ] =16*15*14*13/(4*3*2) = 4 * 5 * 7 * 13 = 1280 Oh well

**math**

21/2 = 10.5 so try 10 + 11

**physics**

143 = m g + m a = m (9.81+0.762) m = 143/(9.81+.762) weight = m g

**physics**

g(Re/r)^2 = (1/4)(9.81)

**physics**

6.5 * 10^5 I expect you mean and 1.8*10^7 F = m a 6.5 * 10^5 = 1.8*10^7 a a = 3.61*10^-2 m/s^2 90 km/h (1 h/3600s)(1000 m/km) = 25 m/s v = a t 25 = 3.61*10^-2 t t = 6.93 *10^2 s = 693 s = 11.5 min

**Interferometry carried to an unimaginable (for me) extreme**

You better Google LIGO, but that is the whole thing. There is no simple reply really.

**physics**

6 g - T = 17 a T - mu(11 g) = 11 a what is a? d = (1/2) a t^2 1 = (1/2)a(1.48)^2 a = .913 m/s^2 6 g - T = 15.5 so T = 6 g - 15.5 so 6 g - 15.5 - 11 g mu = 10.0 let g = 9.8 and solve for mu

**Math**

LOL, cost / number of sprays

**physics**

vertical: Ftop = mg + Tt = m v^2/R Fbot = Tb-mg = m v^2/R so max is Tb = m g + mv^2/R so mg +Tt = Tb-mg 2 mg = Tb-Tt LOL, could have guessed Horizontal T = m v^2/R given Tb = 1.066 T mg + mv^2/R = 1.066 mv^2/R g = .066 v^2/R so v^2 = g R /.066

**Maths**

one at x = 0 then 10 more at 5, 10, 15, 20, 25 , 30, 35, 40, 45, 50 You always have one more fence post than panels of fencing

**Maths**

50/5 + 1 = 11 (one is at x = 0)

**Social Sudies**

fishing if the ^%$&* feds would let you fish.

**physics**

I do not see the figure but am at a loss to understand how the ledge has anything to do with it unless he hits it. u = 17 m/s until splash Vi = 0 h = 7.9 m h = 4.9 t^2 so t = 1.27 seconds v = 9.81 t = 9.81*1.27 = 12.5 m/s speed = sqrt (17^2 + 12.5^2)