Thursday
August 25, 2016

Posts by Damon

Total # Posts: 26,783

physics
when 4 t = 2 pi we have gone around the circle from t = 0 so 4 T = 2 pi T = 2 pi / 4 = pi/2
February 28, 2016

Chemistry
http://www.youtube.com/watch?v=MKLi-V0CY9M
February 27, 2016

Math
2(x-4)+y=6 3x-2(y-3)=13 2 x - 8 + y = 6 3 x - 2 y + 6 = 13 2 x + y = 14 3 x -2y = 7 y = 14 - 2x use that 3 x - 2 (14-2x) = 7 3 x - 28 + 4 x = 7 7 x = 35 = 7*5 so x = 5 go back and find y
February 27, 2016

Math
y= -3/2x-1 which I assume means y = -(3/2)x - 1 so use that 2 [ -(3/2)x - 1 ] - x = -10 -3 x - 2 - x = -10 -4 x = -8 x = 2 etc
February 27, 2016

Physics
well, you have a + 80 e charge fired at a +1 e charge they repel each other How close will the proton get to the 80 protons? when the kinetic energy of the oncoming proton is used up climbing the potential hill of the 80 protons. it stops and backs away Ke = (1/2) m v^2 ...
February 27, 2016

physics
No conduction or convection through vacuum, only radiation (use shiny material to reflect)
February 27, 2016

physics
i = 25/Requivalent = 1 amp so we need Req = 25 In parallel Req = R1R2/(R1+R2) 25 = 50 R2/(50+R2) 25 (50 + R2) = 50 R2 50 + R2 = 2 R2 R2 = 50 which we could have guessed :)
February 27, 2016

PHYSICS
So where are your answers?
February 27, 2016

MATH
there are 3 ft per yard there are 9 ft^2 per yard^2 w = (20/3) yards so (20/3) L = 396 L = 3 * 396 / 20 yards multiply by 3 if you want feet
February 27, 2016

Physics
i = V/R = 12 / .004 amps P = i V = 144/R Joules i = 80 R = V/i = 12/ 80 external resistance Rx = R - .004 power to motor = i^2 Rx = 6400 Rx
February 27, 2016

Figures missing
Probably F * 49.6 = 1460 * 1.90 but I do not see a figure
February 26, 2016

science
100 = (1/2) a t^2 so 200 = a (25) a = 8 m/s^2 F = m a = (200/9.81) 8 F = 163 N That is a pretty light bike if it has a rider, perhaps a small child.
February 26, 2016

Stats please help
5/6 * 5/6 * 5/6 * 5/6 = answer = (5/6)^4 = .482
February 25, 2016

MATH
yes, although you sure use a lot more steps than I :) -4+1 = -3 -3*4 = -12
February 25, 2016

history
Now I may explode being from Massachusetts so I think you better Goggle them.
February 25, 2016

Check math please!
Yes, both right
February 25, 2016

Check math please!
second one same method 5/9 yes consonant =2/3 so not is 4/9 agree - note I used opposite approach from you, same answers :)
February 25, 2016

Check math please!
Anna mixes the letters S, E, L, E, C, T, E, and D thoroughly. Without looking, Mary draws one letter. Expressed as a fraction, decimal, and percentage, what is the probability that E will NOT be the letter Mary selects? A. 3/8, 0.375, 37.5% B. 8/5, 1.6, 16% C. 5/8, 0.625, 62.5...
February 25, 2016

we do not have your drawing
so we do not have the directions of 1 and 2 we know that the total east (x) momentum must be zero and the total north (y) momentum must be zero
February 25, 2016

MATH
yes
February 25, 2016

Math
8.6 cm ( 50 mi/2 cm) = 215 mi
February 25, 2016

Math
.15 * 8.25 about .8 + .4 = 1.2
February 25, 2016

Math
5 * .06 * 2000 = 600 so yes and see you can check it easily :)
February 25, 2016

science help PLS
I would bet on b but around here the problem is sea gulls
February 25, 2016

Math
yes, did that a while ago
February 25, 2016

physics
lets do adolph (1/2) m v^2 = m g h v^2 = 2 g h = 2 (9.81)(.56) so v = 3.31 m/s at push so adolph momentum = 104*3.31 = 345 kg m/s Ed has the same magnitude of momentum 80 V = 345 Ved = 4.31 m/s 4.31^2 = 2 (9.81) (h) h = .9464 m
February 25, 2016

Mathematics
find slope of tangent dy/dx 2 x + 2 y dy/dx - 2 -4 dy/dx = 0 dy/dx (2y-4) = 4 - 2x dy/dx = (4-2x)/(2y-4) at x = 5 and y = -1 dy/dx = (4 -10)/(-6) = -6/-6 = 1 :) slope of normal = -1/slope = -1 so y = -x + b -1 = -5 + b b = 4 so in the end y = -x + 4
February 25, 2016

Math
(z - 2 +3i)(z -2 -3i) = 0 commutative property to multiply z (z -2 -3i) = z^2 -2 z -3 z i -2(z -2 -3i) = -2 z + 4 + 6 i 3i(z -2 -3i) = +3zi -6 i + 9 add ------------------------------ = z^2 - 4 z + 13 so a = -4 and b = 9
February 25, 2016

Math
matrix for reflection over y axis: -1 +0 +0 +1 dilation matrix r r or r r matrix multiplication is not necessarily comutative dilate first r r * x y = r x, r y then reflect rx , ry * -1 +0 +0 +1 = -rx , ry now reflect first -1 +0 |x| +0 +1 |y| = -x , + y now dilate -rx , + r y...
February 25, 2016

linear programming
c = acres of corn w = acres of wheat constraints: c+w </= 100 graph that line,shade under wheat cost = 20 w corn cost = 40 c 20 w + 40 c </= 2400 graph that line, shade under wheat labor = 4 w corn labor = 16 c 4 w + 16 c </= 800 graph that line, shade under Now the ...
February 25, 2016

Maths
3 y^2 dy/dx - dy/dx / y^2 = 2 x -7 dy/dx dy/dx (3 y^2 -1/y^2 + 7) = 2 x dy/dx = 2 x /[ 3 y^2 -y^-2 + 7 ]
February 25, 2016

physics
net north = 8 - 2 = 6 Newtons net east = 6-4 = 2 Newtons |F| = sqrt (36 + 4) = 2 sqrt 10 tan angle n of e = 6/2 = 3 angle n of e = 71.6 degrees north of east or 90 - 71.6 = 18.4 degrees east of north (compass direction)
February 25, 2016

Physics
mechanical advantage = 13.4/1.34 = 10 weight = 53.4 g = 53.4*9.81 divide by 10 for input force 5.34 * 9.81 = 52.4 Newtons input
February 25, 2016

Physics
Work = force * distance = 13.4 *30 = 402 Joules (1/2) m v^2 = 402 1.524 v^2 = 804 v = 22.9 m/s
February 25, 2016

MATH PLEASE
x(5.49) = (5.49 - 2.25) x = .59 59 %
February 25, 2016

MATH PLEASE
1.4 * 12.95 = 18.13
February 25, 2016

MATH PLEASE
.52 s = s - 38.87 38.87 = .48 s s = 80.98
February 25, 2016

Chemistry
N2H4 + N2O2 = 2H2O + 2 N2 limited by .3 mol N2H4 so get .6 mol N2
February 25, 2016

History
agree, see: http://www.ourdocuments.gov/doc.php?flash=true&doc=21
February 25, 2016

Pre Cal
assume you mean x^2 + y^2 = 0 That is a circle of zero radius with center at the origin :) In other words a dot at the origin.
February 25, 2016

Science
Looks like it reacted chemically with something in the air to me :)
February 25, 2016

math
first one black = 26/52 = 1/2 second one black = 25/51 third one black = 24/50 fourth one black = 23/49 etc until we get to number 12 then multiply all those fractions that means you got every king, queen and jack 4 kings + 4 queens + 4 jacks = 12 of the 52 card 1 = 12/52 ...
February 25, 2016

MATH
3 x - y = 4 3 x - y = 6 never cross -parallel, no solution 2 x - y = 1 3 x + y = 6 --------------add 5 x = 7 x = 7/5 etc 1 x - 5 y = 5 3 x + 1 y = 7 multiply first by 3 3 x -15 y = 15 3 x + 1 y = 7 ---------------subtract -16 y = 8 y = -1/2 etc
February 24, 2016

Math
21 * 7 = (1 - 5/8) p = (3/8) p p = 49*8 = 382 pages
February 24, 2016

Algebra
y = - x^3 no y = -3^x would be but not this
February 24, 2016

Algebra: Check Answer
LOL no need to ask, plug back in h = -16(10.4)^2 + 156(10.4) +105 = -1730.56 + 1622.4 + 105 = -1730.56 + 1727.4 close enough to the ground :)
February 24, 2016

Math
Yes dA/dr = 2 pi r = 6.28 r correct however think a little more dA = 2 pi r dr = circumference * dr If you draw a picture of a circle r and then one outside it with radius r + dr You will see immediately that the change in area is the strip of length 2 pi r times the width dr
February 24, 2016

Math
dA = 2 pi r dr yes, correct however notice that this is simply the circumference the new area added is the circumference * dr
February 24, 2016

math
Yes we agree but I simplified
February 24, 2016

math
I assume dy/dx=(4sqrt(y)ln x)/x y^-.5 dy = 4 (ln x /x)dx y^.5 = 2 [ .5 ln^2 x ] y^.5 = ln^2 x y = ln^4 x + c
February 24, 2016

Physics
bullet momentum = .017 v total mass = .017+1.2 = 1.217 kg final momentum = initial momentum .017 v = 1.217 V' V' = .014 v normal force on table = m g = 1.217 (9.81) friction force = .23*1.217*9.81 = 2.75 Newtons work done = 2.75 *8.6 = 23.6 Joules so 23.6 =(1/2)mV'...
February 24, 2016

Algebra 2
yes all 3 are correct but it is easier to use sin and cos sin^-1 (3/19) and cos^-1 (18.8/19)
February 24, 2016

ALGEBRA
surface area = area of top + area of bottom + area of side = pi r^2 + pi r^2 + 2 pi r h = 2 pi (r^2+ r h) = 2 pi r (r + h) = 2 *pi*4 * 10 = 80 pi volume = pi r^2 h = pi *14 * 6 = 84 pi
February 24, 2016

Math
let z = y^.5 then dz = .5 y^-.5 dy dy = 2 y^.5 dz = 2 z dz 2 z dz /(z cos^2 (z) ) = x dx dz/( cos^2 (z)) = .5 x dx tan z = .25 x^2 + constant tan y^.5 = .25 x^2 + constant
February 24, 2016

Mensuration
Now I showed you how to do one by subtracting rectangles. You do this one.
February 24, 2016

Math
That is quite a markup : I have a sneaking suspicion that they mean 140% markup but will do it as stated .75 * price = 39.95 so usual price = 53.27 cost + 2.40 * cost = 53.27 3.40 * cost = 53.27 cost = 15.67 39.95 - 15.67 = 24.28
February 24, 2016

Trigonometry
m and j tan 30 = m/15 tan 45 = 1 = j/15 j - 15 and m = 15 tan 30 = 8.66 m+j = 23.7
February 24, 2016

Precalculus
sec 4x = 1/cos 4x I can not graph it for you here but note that cos 90 or pi/2 = 0 so you are going to have a bunch of vertical asymptotes
February 24, 2016

Mensuration
the original sheet is 30*20 = 600 cm^2 the remaining sheet is 30-8 by 20-8 or 22 * 12 = 264 cm^2 so you removed: 600 - 264
February 24, 2016

Calculus
pi/3 = 60 degree just so I do not have to use radians on my calculator :) c^2 = a^2 + b^2 - 2 a b cos C get initial stuff first cos 60 = 1/2 sin 60 = .866 c^2 = 64 + 169 - 208 cos 60 c^2 = 233 - 104 = 129 c = 11.4 now do the problem 2 c dc/dt = -208 (-sin 60) dC/dt so dc/dt = ...
February 24, 2016

Math
i = -75 p^2 + 600 p if p = 3 i = -75 (9) + 1800 1,125 = -75 p^2 + 600 p 75 p^2 -600 p + 1,125 = 0 solve quadratic for 2 values of p. Throw out any negative one etc for max I assume you do not know calculus so complete square to find vertex 75 p^2 - 600 p = -i p^2 - 8 p = -i/75...
February 24, 2016

statistics
I will do three cards, you do five. 52 cards, 26 are red so find probability of all black first draw 26/52 = 1/2 second draw 25/51 third draw 24/50 = 12/25 prob of all black =.5*25/51*12/25 =.118 so 1-.118 = .882 for at least one red in three draws
February 24, 2016

physics- check this out
v = Vi + a t v = 0 at stop a = -Vi/t = -35 m/s^2
February 24, 2016

Physics
7 t = d 13 t = d+42 so 6 t = 42 t = 7 7 t = d = 49
February 24, 2016

physics
A kilowatt is 1,000 Watts
February 24, 2016

Physics
I will have to guess at your drawing. Both objects fall the same. The first one keeps its horizontal velocity so both fall 1.14 meters v = g t = 9.81 t 1.14 = (1/2) g t^2 = 4.9 t^2 so t = 0.482 second fall time for both so vertical velocity of both is 9.81 * .482 = 4.73 m/s ...
February 24, 2016

physic
falls 63 m 63 = 4.9 t^2 calculate t which is time in air now range = 20 t the end.
February 24, 2016

physics
Kilo
February 24, 2016

physics
22.61 g/cm^3 * (100 cm/m)^3 (1kg/1000g) = 22,610 kg/m^3 by the way water is about 1000 kg/m^2
February 24, 2016

????
You forgot the equation
February 24, 2016

physics
20 east
February 24, 2016

physics
I assume you mean 8 hours. Velocity is the displacement /time and direction Here that is 320/8 or 40 mph North The 400 zigging and zagging is irrelevant for velocity but important if you wanted speed instead of velocity
February 24, 2016

please help
Please just do what I suggested. Goggle Mt Kilimanjaro and those countries.
February 24, 2016

African climates - where to start?
I do not know what to say. Except for one mountain (http://www.tanzaniaparks.com/kili.html) there is not much snow. However everything else is there :) Desert in the North, riverine in the Nile valley, jungle in the center and down the Congo river. Savannas, farmland, grazing ...
February 24, 2016

science
when the potential (voltage) is different in different places on the conductor.
February 21, 2016

Science
It doubles every (1/4) day? in 7 days it doubles 28 times 2^28 = 268,435,456
February 21, 2016

Science
Maybe you mean Bernoulli : (1/2)rho v^2 + rho g h + p = constant If flow is constant in time and no frictional losses rho = density h = altitude p = pressure g - gravitation acceleration v = speed
February 21, 2016

Physics
I can not sketch it for you. v = (2t+1.34) i + 3.34 j + (6t^2 - 8t) k so put in t = 2 a = 2 i + (12t-8) k again use 2 for t
February 21, 2016

Physics
A: v = 10 pi/(10.34) Ac = v^2/r = 20 pi^2/(10.34)^2 B: v = 20 pi/(10.34) Ac = 40 pi^2/(10.34)^2
February 21, 2016

Maths
(-4/3) x = 16/3 -4 x = 16 x = -4
February 21, 2016

science
60min/hr * 60 sec/min = 3600 seconds/hour 2 * 3600 + 35 = 7235
February 21, 2016

Chemistry
we are close to STP here where one mol is 22.4 liters 58.4/22.4 is around 2.61 moles 10.3/2.61 = 3.95 grams/mol Helium maybe ?
February 21, 2016

Algebra
Oh well, I'll play 300 = k * 3^2 * 10.62 so k = 300/(9*10.62) = 3.14 remarkable :) in fact v = pi r^2 h = pi * 3^2 * 10.62 = 300.27 :) so we say v = 3.14 * r^2 *h = 3.14 * 16 * 15.92 =785 cm^3
February 20, 2016

Physics
horizontal rope force= 100 cos 60 = 50 N so a) work done by tension = 50*15 = 750 Joules b) NONE !!!! there is no vertical displacement !
February 20, 2016

Math
.6 (299) = 179.4
February 20, 2016

math
I guess you mean circumference of a circle of radius 5.5 in if so 2 pi r = 11 pi
February 20, 2016

High school calculus
I have a extra b in there.
February 20, 2016

High school calculus
dy = (bx+5)^-3 dx let z = bx+5 then dz = b dx and dx = (1/b) dz dy = (1/b) z^-3 dz y = (1/b)(-1/2)z^-2 + c y = -1/(2b z^2) + c but z^2 = b^2x^2 + 10 bx + 25 so 2 b z^2 = 2b^3x^2 + 20 b^2 x + 50 b so y = -1/(2b^3x^2 + 20 b^2 x + 50 b) + c
February 20, 2016

Algebra
t = k r^2/z^3 4 = k 36/27 k = 3 so t = 3 r^2/z^3 ============================ c = k d^2/L .54 mho = k 3^2/50 k = 50 * .54 /9 = 3 again LOL (note - in your units which are not the ones a physicist would tend to use)
February 20, 2016

math
Some blame it on people like Pythagoras but I think folks along the Indus River thought it up to keep track of monsoons and crops and water level and stars and stuff. The really important guy was Sicilian but everyone calls him Greek named Archimedes. He not only figured out ...
February 20, 2016

phy 231
centripetal acceleration Ac = v^2/r = r omega^2 omega is part a r = radius there = Re sin 49 [ note - usually we use latitude which is angle North of the equator in this case cos(90-49)]
February 20, 2016

physics
(1/2) a t^2 = h (1/2)(9.81)(36) = h in meters
February 20, 2016

math
I can guess based on the possible answers. The only one with a y axis intercept is y = 5 x + 2 that is $2 to walk in the store and a unit rate of $5 per sandwich
February 19, 2016

Statistics
You are welcome.
February 19, 2016

Statistics
http://davidmlane.com/hyperstat/z_table.html
February 19, 2016

Math
http://www.jiskha.com/display.cgi?id=1455913440
February 19, 2016

Just did it
see below
February 19, 2016

Math
.80 * .75 * 179.99
February 19, 2016

physics
work output = 500 * 1.7 = 850 Joules work input = 1000 Joules efficiency = (850/1000)100 = 85 % since you did not say what the velocity ratio was, how would I know what the mechanical advantage was? They are the same on inverses depending of which way you write the velocity ...
February 19, 2016

chemistry
if they have more than one electron or lack of electrons in complete outer shell they can lose or gain electrons to form complete outer shells. Google oxidation reduction
February 18, 2016

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