# Posts by Damon

Total # Posts: 31,634

Mathmatics
120/360 = 1/3 so we want one third the area of the circle (1/3) pi (81) =

Math
7 (10 + 2 ) ?

Algebra
s = height above ground s = 60 + 20 t - 4.9 t^2 (standard physics equation on earth) at t = 0 s = 60 (clearly :) now when does it hit the bleak earth? That is when s = 0 4.9 t^2 - 20 t -60 = 0 solve quadratic and use the positive t (the negative t was back before you threw it ...

hmmm .94^6 * 12500 = 8623 slope = m = (5-2)/(-3+4) = 3 y = 3 x + b 5 = 3(-3) + b 5 = -9 + b b = 14 so y = 3 x + 14 so none of your answers. You probably have a typo. even is 2, 4, 6 so 4 of the six sides are even or 5 4/6 = 2/3

physics
to prevent sliding down: F sin T >/= m g - mu m g cos T to prevent sliding up F sin T </= m g + mu m g cos T

physics
If theta is the angle above horizontal and there is no friction then F sin theta must be = m g if theta = 0 , F is infinite if theta = 90 degree, F = m g

math
Area of what I assume is supposed to be a rectangle is (1/2)(1/4) = 1/8 of a square mile

Algebra
In A there are two values of y , -2 and + 2, for the same value of x, 4 That is a no no

Algebra
You are welcome.

Algebra
I guess maybe you mean: x/(x-2) + (x-1)/(x+1) = -1 multiply everything by (x-2)(x+1) x(x+1) + (x-1)(x-2) =-(x-2)(x+1) x^2 + x +x^2 -3x +2 = -[ x^2-x-2 ] 2 x^2 -2x +2 = -x^2 + x + 2 3 x^2 - 3 x = 0 3 x (x-1) = 0 x = 0 or x = 1

Math
well ok, then your way so let (1 - x/100) = z 1/2 = z^8 ln .5 = 8 ln z so ln z = -.693/8 = - .0866 then z = e^-.0866 = .917 x/100 = 1-.917 = .083 so x = 8.3 % note my way uses continuous rate, yours is yearly change.

Math
dn/dt = -(x/100) n dn/n = -(x/100) dt ln n = (-x/100 + C n = e^(-x/100 + C)t or n = c e^-(x/100)t at t = 0, n = N so c = N at t = 8, n = N/2 so c = N and N/2 = N e^-8x/100 or .5 = e^-.08x ln .5 = -.08 x -.693 = -.08 x x = 8.725 %

Dynamics
Ac = v^2/R mg sin a = mv^2/R so sin a = v^2/(R g) and v = 100,000/ 3,600 = 27.8 m/s solve for angle a

Dynamics of rigid bodies
tan 10 = m v^2/R / mg = v^2/(R g) but R/0.40 = sin 10 so R = 0.40 sin 10 T = m sqrt [(v^2/R)^2 + g^2]

Dynamics of rigid bodies
when v^2/R = g, that is it

Dynamics of rigid bodies
m omega^2 R = 400 0.300 w^2 (0.60) = 400 solve for w ( omega ) in radians/sec then w * 1 rev/2pi rad * 60 sec/min = RPM

Dynamics of rigid bodies
impulse = change of momentum force = impulse/time

Chemistry
How do you expect to get from mL to moles if you do not know how much HCl is in the water? Where did you get the 1.19 ? That is why we do not understand your answer.

sir steve damon reiny steve help maths
Well, it depends where he is I think at the beginning x = man from light pole= Xi then x = Xi + 1.5 t if he starts at the pole at t = 0 then Xi = 0 but we can not assume that y = shadow length=(2/6)(x+y) or y = x/2 so y=(1/2)(Xi + 1.5 t) and dy/dt = (1/2)(1.5) = 3/4 m/s

Algebra
do you mean sqrt (97x)???? 97 is a prime number so if we have sqrt(97*97) that is 97 so x = 97 works 97 times any perfect square like 4 or 9 also works

I did the first one below.
Now you try.

algebra 1
x - 5 remainder 5 ------ x - 5 ==== ________________ x-5 |x^2 - 10 x + 30 ==== x^2 - 5 x =====-------------- ======== - 5 x + 30 =========- 5 x + 25 ---------------------- =======Remainder = 5

Algebra 2
at two pi they are both zero but at pi/2 sin is 1 and tan is oo at pi/3 sin is sqrt3/2 and tan is sqrt3 at 3 pi/2 same problem as at pi/2

Science
Yes.

solve what?
Did you try to copy and paste an equation? That does not work.

Engineering Systems
A vehicle jack exerts at least two forces, one up on the vehicle equal to the vehicle weight and one down on the ground equal to the vehicle weight plus the jack weight. Of course gravity exerts a force equal to the vehicle weight so that the net force on the jack is zero. You...

math science geography
change in momentum = Force * time = 15*4 = 60 kg m/s

Math
assuming that it is 3/4/13 by mass and not by atoms: 3x + 4x + 13 x = 4 kg 20 x = 4 x = .2 kg Ni = 3x = .6 kg Zn = 4x = .8 kg Cu =13x = 2.6 kg

algebra 1
well, I need two numbers one apart that multiply to 156 try 12 and 13 :) (y-13)(y+12) for 39 they must differ by 9 3 and 13 nope, both prime so no other way ,,, hopeless too bad it was not r^2-10r -39 :)

Science
They tell you that the water has to seep through it. Therefore concrete, packed clay, plastic sheeting, and roof tar, all of which are supposed to be waterproof, will NOT work. Use the sandy gravel.

Math
50 t - 40 t = 18

Math
d = v t 60 t = 40 (t+1) 20 t = 40 t = 2 so d = 60*2 = 120 miles or d = 40*3 = 120 miles

Science
whoops, Dr Bob is right, Ph is neutral ,about 7.

Science
nono3 is a base, not acid. It should turn the phenolpthalein pink if the Ph is over about 8

Math

Math
speed = 50 miles/60 minutes d = v t 5 = (5/6) t t = 6 minutes 4:54 pm

Geometry
using law of cosines 8^2 = 7^2+9^2 - 2*7*9 cos A 64 = 49 + 81 - 126 cos A cos A = 66/126 x^2 = 130 - 126 cos(180-A) but cos(180-A) = -cos A so x^2 = 130 + 126(66/126) x^2 = 196 x = 14

Physics HELP!
if they stick together: original momentum = 2.1*10^4 * 2 final momentum = 4.2*10^4*v so v = 1 m/s initial ke = (1/2)m v^2 final ke = (1/2)(2m)(v/2)^2 final/initial = [2v^2/4]/v^2 =1/2 so you lose half =============== LOL if perfectly elastic, first one stops, second continues ...

math
for example if you know jack bought 20 apples then 20 = (x-30)/3 60 = x-30 x = 90 for Henry check 90/3 - 10 = 20 for Jack

math
(x/3)-10 = Jack = (x-30)/3 yes, the right and the left are equal, but you can not solve for x without knowing more.

Physics
force down ramp = m g sin 30 = .5 m g normal force = m g cos 30 maximum friction force = mu m g cos 30 slides if: .5 m g > mu m g cos 30 so mu >/= .5/cos 30 = .58

chemistry
1/4 liter so four times 5.9 grams in liter = 23.6 grams in a liter Na = Na2CO3 = 106 grams/mol so molarity = 23.6/106 mols/liter

Geometry
half triangle base = 6/tan 30 so base = b = 12/tan 30 sin 60 = h/b so h = b sin 60 A=(1/2)bh =(1/2)(12/tan30)(12/tan 30)sin 60

MMATH08
15 - 3 = 12 12 * 15 = 180 meters total time = 180 meters/2 meters/sec = 90 sec

Physic
x = 2 cos 40 + 4 cos 127 y = 2 sin 40 + 4 sin 127 magnitude^2 = x^2+y^2 tan angle to x axis = y/x

physics particular paragraph
The basic functional structure of an optical fiber consists of an outer protective cladding and an inner core through which light pulses travel. The overall diameter of the fiber is about 125 ?m and that of the core is just about 50 ?m. The difference in refractive index of ...

physics
better: http://www.boundless.com/physics/textbooks/boundless-physics-textbook/geometric-optics-24/reflection-refraction-and-dispersion-169/total-internal-reflection-and-fiber-optics-609-6258/

physics
Snell's Law critical angle http://hyperphysics.phy-astr.gsu.edu/hbase/optmod/fibopt.html

Math
by the way 45/41 is bigger than one which is a very improbable probability.

Math
p red = 9/41 replace so independent p blue = 10/41 9/41 * 10/41 = 90/1681

CHEK MATH PLZ!!!
yes 9/36 = 1/4 yes half of the table :)

1. agree Power = Voltage* current so i = P/V = 4/120 = .0333 amps 2. R = V/i = V*2/P = 3600 ohms 3. Power * time = energy used = 4 * 2 = 8 watt hours = .008 kwhr .008*.12 = .00096 dollars

Physics
speed = c = about3*10^8 m/s distance=wave length= speed * time frequency = 1/time E = plank's constant * frequency This is basic. Check your text!!!!

Physics
M/m = 1/sqrt(1-v^2/c^2) = 1.15 1 /[1- v^2/(9*10^16)] = 1.15*2

Dynamics
both proceed for time t both are at the same position x=d at time t both started at t = 0 at x = 0 for car d = 6 t for cycle d = (1/2) 4 t^2 so 6 t = (1/2) 4 t^2 3 = t then d = 6*3 = 18

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?

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

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 ...

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)