# Posts by Damon

Total # Posts: 29,990

**LOL**

Right, you want me to write your text book chapter? Here: http://hyperphysics.phy-astr.gsu.edu/hbase/Bohr.html

**Physics**

v = (2 pi R/4) / 2.1 = pi R/(4.2) Ac = v^2/R F = mAc = m v^2/R

**pls help physics problem**

T = moment at pivot = m g (1.55/2) alpha = T/moment of inertia moment of inertia about end = (1/3)mL^2 = (1/3)(m)(1.55^2) so alpha = g(1.55/2) /[(1/3)(1.55^2)] that is part 1 2) 1.02 alpha 3| g = alpha * x

**Math**

b^2-4ac is positive for real roots 4 - 4(1)(1-m) is positive 4 - 4 + 4 m is positive or 4 m is positive so m is positive m>0 for sure now 2 +/- sqrt (b^2-4ac) is positive for positive root 2 +/- sqrt(4-4(1-m) ) is positive 2 +/- sqrt(m) is positive m < 4 so 0 <m< 4

**Math**

along the x (horizontal) axis you would have time along the y (vertical) axis you would have height so the height is a function of (depends on) time so time is the independent variable and height is dependent on age(time)

**chemistry**

for every mol of N (not N2) you get one mol of NH mols of N = 32 g /14 g/mol = 32/14 so we get (32/14) mols of NH3 NH3 = 14+3 = 17 g/mol so (32/14)(17) grams

**Math**

I guess we are talking about one one year period .08x + .06(4800-x) = 348

**Science**

A chemical reaction?

**Trig Help Please**

200 - 30 = 170 sin 42 = 170/x

**Trig**

same as your smokestack problem sin 35.2 = 16/x

**math**

Now about that power stuff, If we can agree that log(ab) = log (a) + log (b) then what is log (a^3) ???? well log (a*a*a) = log(a)+log(a)+log(a) which is of course 3 log (a) :)

**math**

http://en.wikipedia.org/wiki/Slide_rule

**math**

it arrives at 3:54 which is 3:(54-12) = 3:42 on my watch So I probably missed it by seven minutes.

**physics - sort of**

a) Displacement is the vector from the start point to the finish point. We ended up where we started. So ZERO !!!! (this was a trick question) b) I guess we do not know that g = 9.81 m/s^2 or we would not need that 2 seconds given. v = Vi - g t at top v = 0 Vi = g t = 2 g 12...

**stats**

.8*200 = 160 then http://davidmlane.com/hyperstat/z_table.html

**Physics**

max Pe = max Ke (1/2)k Xmax^2 = (1/2) m Vmax^2 (1/2)(400)(.1)^2 = (1/2)(.3)(Vmax)^2 40/3 = Vmax^2

**Social Studies**

I agree. More money deposited for banks to lend out means lower interest rates.

**Engineering science**

a. displacement = sqrt(600^2+420^2) b. distance = 600+420 = 1020 so speed = 1020/time c.average velocity = answer from part a / time but velocity also has a direction since it is a vector tan angle east of north = 420/600

**Fluid Dynamics**

If there were no frictional losses, no, the velocity would increase to maintain the same flow rate which is velocity times area. However In real life as the velocity increases the losses of total energy due to friction (viscosity) increase and the flow will slow down for a ...

**Math Help?**

x<0 is left y<0 is down so down to the left = Third quadrant :)

**algebra**

The form is y = m x + b m is the slope b is the y axis intercept, where the line hits the y axis when x = 0 so the slope here is m = 2 and the line will look like y = 2 x + b so it is not C and it is not D now what happens when x = 3? y = 2(3) + b = 6+b but y better be 8 so b ...

**Math**

b would be used to eliminate x but you are supposed to eliminate z so c which would give you -4z+4z = 0

**Science please help**

A system which if disturbed tends to return to equilibrium is stable. Think pendulum. A system that if disturbed tends to run away from equilibrium is considered unstable, think pencil standing on your desk on its eraser. Once it falls flat on your desk of course, it becomes ...

**TRIG**

cos 32.1 = side/diagonal = 142.9/x so x = 142.9 / cos 32.1

**Physics**

1 atm = pressure at surface = 101325 Pascals or Newtons/meter^2 p = pressure at surface + density*g * depth so 3 atm at 2 atm below surface = 202650 Pascals = 1240 * 9.81 * depth so depth = 16.7 meters

**Physics**

In the vertical direction mg down from gravity = mg up from the floor so the vertical acceleration = 0 In the horizontal direction there is only one force, friction, deaccerating -0.30 m g = m a so a = -0.30 g = -0.30 * 9.8 =-2.94 m/s^3 Now if the initial speed is 3 then v = 3...

**physics**

use sci units L = 2.50 meters m = 0.5 kg g on earth is about 9.81 m/s^2 amplitude of .25 is irrelevant to usual approximation but see http://en.wikipedia.org/wiki/Pendulum ignoring amplitude: T = period = 2 pi sqrt (L/g) T = 2(3.14)sqrt (2.5/9.81) seconds frequency = 1/T Hz

**math-precalculus**

radius = 25 height of center = 26 T is angle from vertical height = 26 + 25 cos T so 44 = 26 + 25 cos T 25 cos T = 18 cos T = .72 T = 44 degrees from vertical so 88 degrees out of 360 are above 44 meters (88/360)6 = 1.47 minutes

**Science**

A thrown football has both speed and height. The speed results in kinetic energy Ke = (1/2) m v^2 The height gives potential energy Pe = m g h The sum of potential and kinetic is constant if there is no air drag. That is the total mechanical energy. As the height goes up, the ...

**Math**

c = 0.30 * total so total = c/0.30

**Physics 1401**

object mass = 30/g weight of water displaced = (30-20) = 10 N water weight = water mass * g so water mass = 10 N/g but water volume = water mass * 1 m^3/1000 kg so water volume = (10/g)/1000 meters^3 water volume = .01/g = object volume so object mass/object volume = object ...

**algebra**

downstream speed = (v+c) upstream speed = (v-c) time = t (v+c)t = 45 (v-c)t = 27 (12+c)t = 45 (12-c)t = 27 so 45/(12+c) = 27/(12-c) 45 (12-c) = 27 (12+c) etc

**calculus**

I may look easy but it took me a while :)

**calculus**

dy/dx=cos x+ z sec^2 x+ dz/dx tan x = z + cos x so z = z sec^2 x + dz/dx tan x z(1-sec^2x) = dz/dx tan x z (-sin^2x/cos^2x) = dz/dx (sin x/cos x) z(-tan x ) = dz/dx dz/dx = -z tan x ------------------------- d/dx(z+cos x)=d^2y/dx^2=dz/dx-sin x = -z tan x-sin x which lo and ...

**Science please help**

also non-animal things like styrofoam, fiberglass insulaton, vacuum, etc, etc, etc

**trigonometry**

3,4,5 right triangle so sin = 4/5 so cosec = 5/4 tan = 4/3 so cot = 3/4 so (5/4)/(1 + 3/4) = 5/7

**math**

50 = 35 t - 5 t^2 5 t^2 - 35 t + 50 = 0 t^2 - 7 t + 10 = 0 (t-5)(t-2) = 0 2 on the way up and 5 on the way down

**Math**

divide both sides of 5 (3cd+b) = A(3cd+b) by (3cd+b)

**Math**

hummm 6+9 IS NOT 18 BUT 15 6 c d + 2 b + 9 c d + 3 b = A(3cd+b) 15 c d + 5 b = A(3cd+b) 5 (3cd+b) = A(3cd+b) A = 5

**Chemistry**

NH3 = 14 + 3 = 17 grams/mol 203.5/17 = 12 mols of NH3 so 12 mols of HCN result HCN = 1 + 12 + 14 = 27 grams/mol so 12 * 27 grams HCN

**at STP ?**

.27 mols HCl agree so .135 mols CO2--- agree at standard temp and pressure a mol is 22.4 liters .135 mol*22.4 liters/mol= 3 liters a liter is 1000 cm^3 so I get 3,000 cm^3

**math**

well it is more than 180 and less than 270 so I claim it is in the third

**Math**

LOL, you have to be more explicit about what you want. For example: x^2 + y^2 = r^2 is a formula for a circle of radius r and center at the origin in x,y plane

**Calculus**

when y = 1, x = 1 when y = 8, x = 2so we seem to be talking about the sort of triangle between (1,1) (2,1) and (2,8) could be vertical cylinders of wall thickness dx and height (x^3-1) and radius x from x = 1 to x = 2 v = integral [2 pi x(x^3-1)]dx from x = 1 to x = 2 2 pi [ x...

**typo and easier way**

by the way, you could have used the average speed Vav = 3*10^6 so t = 10^-2/3*10^6 = (1/3)*10^-8 (not 10^-10)

**uni of huddersfield**

F = m a a = change in v/ change in t v = Vi + a t 6*10^6 = 0 + a t = a t x = Xi + Vi t + (1/2) a t^2 10^-2 meters = 0 + 0 +(1/2) a t^2 so a t^2 = 2*10^-2 and a = 6*10^6/t so 6*10^6/t * t^2 = 2*10^-2 6 t = 2*10^-10 seconds t = (1/3)10^-10 second then a = 18 *10^4 m/s^2 now F = ...

**science**

because if the temp goes up the bar will expand. A reference temperature must be chosen so that the length is standard. Zero is easy, water freezes there :)

**math**

circumference = 2 pi r = 2 *3.14159* 26 inches goes 32 * circumference /12 feet

**physics HELP!!**

http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/gratcal.html

**Physics**

Obviously A will work but note that 1.9/2 = .95 That would have a node at each end and would be the first resonance, lowest frequency. so also D

**chemistry**

P V = n R T You have three times as many molecules or mols new n = 3 * original n V, R and T the same so new P = 3*old P

**Science**

Correct. http://edtech2.boisestate.edu/lindabennett1/502/periodic%20table%20e%20config/PTable_trends%20around%20table.html

**physics**

time for car a is t+2 time for car b is t distance car a = (15000 m/3600 s)(t+2) distance car b = (1/2)(3)t^2 so when does car a travel the same distance as car b? (150/36)(t+2) = (3/2) t^2 solve quadratic, use the t that makes sense :) speed of b = 3 t

**math**

(4/3) pi r^3 = .5236 = 0.5 in^3

**Calculus**

at b = x^3 the change of the integral with x = y'(x) [ it is the value of the function at that limit ] =10 x^3/2 sin( x^3 )

**physics**

remember wavelength = speed of sound * T = speed of sound / f and then http://www.physicsclassroom.com/class/sound/Lesson-5/Open-End-Air-Columns

**physics**

http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/souspe.html frequency closed end pipe

**physics homework**

impulse = change of momentum all vertical, no change in horizontal speed from -v cos 60 to + v cos 60 2 m v cos 60

**physics**

initial momentum north = 55*1.1-7*1.8 Now I assume she picks the dog up and the system moves on with the same momentum final momentum north = (55+7)v so 62 v = 55*1.1 - 7*1.8

**physics**

well, the initial momentum was zero so the final momentum must be zero. I assume the first cart goes back and the mouse and cart two go forward so 0 = -.35*.8 +(.054+.25)V2 .28 = .304 V2

**Physics**

0 = Hi - Vi t - 4.9 t^2 0 = Hi - 0 (t+4) - 4.9 (t+4)^2 0 = Hi - 40 t - 4.9 t^2 ------------------------------ Hi = 4.9 t^2 + 40 t Hi = 4.9(t^2+8t+16) --------------------- 4.9 t^2+40 t = 4.9 t^2+39.2t +78.4 .8t = 78.4 t = 98 Hi = 40t+4.9t^2 =40*98+4.9(98^2) =50,980 meters (30 ...

**Physics**

Heat of fusion of water (water to ice transition) is 3,340,000 Joules/kilogram so 2.4 * 3,340,000 Joules The mixture stays at 0 degrees centigrade until the ice is all melted. That is how ice works in your cold drink.

**math**

1.07 * 10^4 = 1.0700 *10^4 so I can count four to the right = 10,700

**Algebra 2**

You are welcome.

**Algebra 2**

Yes like (x-h)^2= 4(a(y-k) is a parabola (x-h)^2/a^2 + (y-k)^2/b^2 = 1 is an ellipse if a^2=b^2 then circle of radius a^2=b^2=r^2 if - sign between, then ellipse turns to hyperbola etc

**Calculus**

one way x = + y^1/2 , double answer for the negative x part 2 int[ x 2 pi (7-y)dy] from y=1 to 7 4 pi int y^.5(7-y)dy 28 pi int y^.5 dy - 4 pi int y^1.5 dy 28 pi {y^1.5/1.5} - 4 pi y^2.5/2.5 at 7 (28/1.5)pi 7^1.5 -(4/2.5)pi 7^2.5 at 1 (28/1.5)pi -(4/2.5)pi subtract at 1 from at 7

**19? typo?**

This question does not make any sense. The mass does not change when it is lifted by Archimedes. the mass is 19 * 1 gram/cm^3 * 20 cm*3 = 380 grams

**math**

That is a horizontal line, changeless forever and ever, no slope at all :)

**physics**

each would create a E vector pointing through the center from the charge segment. The components perpendicular to the diameter add. The components parallel to the diameter cancel each other. So you end up with an E vector perpendicular to that diameter. If you do the other ...

**physics**

3/2 the length same charge so 2/3 the density (3/2) * 10 = 30/2 = 15 so increase by 5 nC

**Statistics**

check AREA box put in Area = .05 result is 95 % are below 698

**Statistics**

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

**Math**

any element in one must be in the other. any element not in one cannot be in the other :)

**Math**

Draw Venn diagram

**Pre-Algebra**

change in y/change in x = (-5-10) / (1+4) = -3 or = (-20+5) / (6-1) = -3 or = (-20 -10) / (6+4) = -3 remarkable, the slope is constant and is -3 so y = -3 x + b now put any of those points in 10 = -3(-4) + b b = -2 so y = -3 x - 2 NOW check that with another point like -20 = -...

**physics**

well let's call the specific heat of water = k. It does not matter what it is now the heat added to the cold = the heat taken from the hot 2000 k (20-5) = m k (70-20) 2000 (15) = m (50) m = 2000 (15/50) grams

**Pre-Algebra**

Base Area * height for CYLINDER pi r^2 h = pi * 16 * 3 = 48 pi BUT for CONE anything pointy with straight sides (1/3) * Base area * height = 48 pi/3 = 16 pi

**math**

(6/7)(7/8)(70) = .75*70

**8th grade math asp help**

top = pi r^2 sides = 2 pi r h pi (64 + 16*12) pi (64 + 192) 256 pi = about 804

**Pre calc**

oh, cos also - in quadrant 3 cos a = -9/11

**Pre calc**

but she said pi/4 :)

**Pre calc**

well, the sides could be 1, (2/9)sqrt10 and hypotenuse 11/9 or 9, 2 sqrt 10, 11 with 2 sqrt 10 opposite ? we know sin ? <0 so ? in quadrant 3 or 4 since tan is +, must be quadrant 3 now actually cos(a-b)=cosa cosb + sina sinb cos a = 9/11 cos b = 1/sqrt 2 sin a = -(2/11) ...

**physics**

if x = a sin wt v = aw cos wt a = -w^2 x when x = 0 |v| is MAX so Ke is MAX total energy is CONSTANT So only acceleration which is proportional to x

**Math gibberish**

Please proof read.

**Trig**

[sin/cos] / [ 1 - sin^2/cos^2 ] sin cos / [cos^2-sin^2] sqrt3/4 / [ 3/4 - 1/4 ] (1/2) sqrt 3

**math**

6/8 = 3/4 3/4 * 28 = 21

**laplace transformation:help damon or steve or rein**

arrggh, you will have to type them in as d^3y/dt^3 -3 d^2y/dt^2-3dy/dt and t^2 e^t

**laplace transformation:help damon or steve or rein**

left http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=122507de3372c73f916a1d07ccb9cf9c&title=Laplace+Transform+Calculator&theme=blue&i0=cos right http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=122507de3372c73f916a1d07ccb9cf9c&title=Laplace+Transform+...

**physics**

reduce distance by half, multiply the force by 2^2 = 4 k Q1 Q2 / d^2

**maths steve reiny bob reiny!!! Help**

y = -2x -3 the slope = -2 y = (1/2)x - 1/2 slope = 1/2 so perpendicular, whew that helps. where do they cross? That is a corner. (x-1)/2 = -2x-3 x-1 = -4x -6 5x = -5 x=-1 y = 2-3 = -1 so other corner is (-1, -1) now draw it and find the other two intersetions

**Calculus**

dy/y = dx/x^2 ln y = -1/x + c y = C e^-1/x http://www.wolframalpha.com/input/?i=Solve++y%27(x)+%3Dy%2Fx%5E2

**Calculus**

http://www.wolframalpha.com/input/?i=Solve++y%27(x)+%3D+x%2Bxy

**math- integral**

what you are really asking is how fast is the area changing at t = x which is the value of the function itself at t = x x^5 sin(-7x-4)

**Calculus**

the value of the function at t = x^2 = (x^2)^x^2

**Please check carefully for typos**

stiffness must be force/distance, for example Newtons/meter. kg is mass, not force and I have no idea what s2 means. similarly b *dx/dt would be a force in Newtons where b would have units Newtons seconds/ meters

**Physics (Attempt 3 for help)**

Yes, it does look familiar :)

**physics**

F = k q1 q2 /d^2 q1*q2 = 6*2 = 12 new q1*q2 = 8*4 = 32 so (32/12)12N = 32 N

**Geometry**

d = length w = width center at 1/2 d and at 1/2 w (1/2)d - (1/2)w = 4 d+w = 56/2 = 28 so w = 28-d d - (28-d) = 8 2 d = 36 d = 18 then w = 10

**physics**

To do positive work, you must push in the direction of motion. That requires an increase of volume as the walls of the balloon move out :) It could be that the internal energy decreases at the same time but you might be putting heat in.

**physics**

10 grams * 2 J/gdegK = 20 J/degK 20J/degK * 10 deg K = 200 Joules to get it all to the boiling point then boil 5 grams with remaining 200 J heat/gram = 200 Joules/5 grams = 40 Joules/gram