Thursday
December 8, 2016

Posts by Damon

Total # Posts: 28,440

science
No way I am going to just say a heat wave is hot. What answers would you give if we were not around?
November 1, 2016

physics
I wonder if the cabinet is accelerating down call it a ma = mg - T m(9.81-a) = 2390 T - .68 * 193 *9.81 = 193 a or 193 a = 2390 - 1287 a = 5.71 m/s^2 (dangerous) m (9.81-5.71) = 2390 m = 583 kg
November 1, 2016

Chemistry help emergency? (theoretical mass/mol)
You do not have enough of one or the other, limiting the amount of Cu resulting. Use the one you do not have enough of. Your mols of Al must be at least 2/3 the number of mols of CuCl....... If it is less use it. If it is more use the CuCl ... and you will have some Al left over
November 1, 2016

Maths (really hard)
what is length AB? sqrt(4+ 64) = sqrt 68 = 2 sqrt 17 so length AC = sqrt 17 what is slope AC? It is -1/slope AB slope AB = -2/8 = -1/4 so slope AC = 4 now point C (x,y) Oh, wow, problem over go right one from A go up 4 from there what is hypotenuse? LOL sqrt 17 !!!! so x = 1...
November 1, 2016

Maths (done question a but cant do b)
-2 + -3 = -5 -5/2 = -2.5 which is y of C 4 ) 6 = 10 10/5 = 5 which is x of C so C(5, -2.5) now AC dx = 5-4 = 1 dy = -2.5 - -3 = .5 d^2 = 1+.25 now CB dx = 6 -5 = 1 dy = -2 - -2.5 = .5 d^2 = 1 + .25 the same
November 1, 2016

LOL - so what is C (?,?)
Do I have to do part a too ?
November 1, 2016

maths
change in y = 6 - (-3) = 9 change in x = 7 -4 = 3 so d = sqrt (81 + 9) = sqrt (90) = 3 sqrt 10
November 1, 2016

Math
You are welcome.
November 1, 2016

Math
85% = 85/100 = 0.85
November 1, 2016

Calculus
You are welcome.
November 1, 2016

Calculus
Sometimes conventional obscurity is insufficient and extraordinary efforts must be made to confuse the student. One seemingly simple but surprisingly effective technique is to reverse the usual roles of x and y.
November 1, 2016

Calculus
yes it is. Perhaps you are misled by the x being the independent variable instead of y When y = 1 x = 1^3 = 9 (1)^2 + 5 = 1 - 9 + 5 = -3 sure enough now the problem dx/dx = 1 = 3 y^2 dy/dx - 18y dy/dx 1 = (3y^2-18y)dy/dx dy/dx = 1/ (3*1^2 -18*1) dy/dx = 1/(-15) = -1/15 amazing...
November 1, 2016

Science
well, probably there was air and water in it and the air expanded in the heat pushing the water out.
October 31, 2016

Math
4 * 7 * 25 = 100 * 7 = 700
October 31, 2016

chemistry
pentaamminesulfatocobalt (III) bromide http://seattlecentral.edu/faculty/dwick/CC%20name.pdf 1L is the one, NH3 and SO4 reversed
October 31, 2016

Physics
I am going to assume a flat and earth and the sun at infinity :) In that case the tip of the hawk's shadow is directly under the hawk and moves at the hawk's horizontal speed. u = 6.09 cos 78.6
October 31, 2016

physics
2 pi radians in 332 sec so omega = angular velocity = pi/166 Ac = omega^2 r = (pi/166)^2 * 2870
October 31, 2016

Science
Hey, come on, if you reverse the direction of the current you reverse the direction of the magnetic field produced !
October 31, 2016

Physics
8 north and 2 east so sqrt(64+4) tan angle north of east = 8/2 = 4 3 + 8 + 5 = 16
October 31, 2016

Calculus
C = 2 pi r so r = 35/pi so dC = 2 pi dr so dr = dC/ (2 pi) = .9/(2pi) a = pi r^2 da = 2 pi r dr da = 70 pi dr da/a = 70 pi dr/a multiply by 100 to get percent
October 31, 2016

4th grade math
1) right, like 18 does not work 2) n = 12 * x*y*z*.... so n = 2 * 6 * x*y*z*....
October 31, 2016

Calculus
let z = t^2-1 then dz = 2 t dt or dt =dz/(2 t) and we have integral of t z^(1/3) dt = t z^(1/3) dz/(2t) = (1/2) z^(1/3) dz Got it :)
October 31, 2016

chemistry
maybe this would help? http://www.coursehero.com/file/p6s4k6su/Bis-ethylenediamine-More-Nomenclature-Feen-2-NO-2-2-2-SO-4-Bisethylenediamine/
October 31, 2016

Physics
if t is RISE time and Vi is initial speed up v = Vi - 9.81 t at top v = 0 so Vi = 9.81 * 36.761/2 (because it spends half the time going up) Now I hope you know 45 degrees gives max range New Vi = Vi sin 45 U = Vi cos 45 with new Vi find time to top same way 9.81 t = Vi time ...
October 31, 2016

Math
two circles of radius 6 in, any bigger will not fit. circle area = 2 (pi 6^2) = 72 pi rectanglearea = 12 * 24 waste = 12 *24 - 72 pi
October 31, 2016

Applied math
5 - (-2) = 5 + 2 = 7
October 31, 2016

Pre Algebra
d = 2 a d = 34 34 = 2a 34/2 = a a = 17
October 31, 2016

algebra 2
210 = 4 (v+w) 210 = 6 (v-w) 105 = 2 v + 2 w 105 = 3 v - 3 w 315 = 6 v + 6 w 210 = 6 v - 6 w --------------------add 525 = 12 v etc
October 31, 2016

Science
V = i R if V increases and i is the same, R must have increased. right
October 31, 2016

Science
second one is right
October 31, 2016

Science
NO F = G M m /R^2 more mass is more gravitational force it remains in orbit because the centripetal force is also proportional to mass m v^2/R
October 31, 2016

Physics 11 urgent Steve, bob, damon pls
PS Perhaps you missed that word "frictionless" Do not think you are pushing that box along a hockey rink. That requires friction and cleats on your shoes if on ice. If no cleats, if the box goes one way you go the other :)
October 30, 2016

Physics 11 urgent Steve, bob, damon pls
Before the push, the momentum of the system was zero so since there is no EXTERNAL force on the student/box system, After the push the total momentum of the system is zero. Therefore If the student goes North then The box goes South if north is + .8 (30) + v (20) = 0 v = -.8(...
October 30, 2016

Calc.
perimeter = 2 x + 2 y cost = c = 14 x + 4 y = 15400 or 7 x + 2 y = 7700 y = -3.5 x + 3850 A = x y = x(-3.5 x + 3850) = -3.5 x^2 + 3850 x dA/dx = -7x +3850 zero when x = 3850/7 etc
October 30, 2016

Calculus AB
f(6) = f(7) + f'(7) * (6-7) f(6) = 34 + 4 (-1) f(6) = 30 not 42 so I disagree
October 30, 2016

Calculus AB
dC/dx = change of totsl cost per change of number og bikes if dx = 1 then dC/dx = cost of that one cost of 2 more is about 2 dC/dx when x = 40 bu you better also have C(40) :) LOL, total cost goes negative for large number of bikes, very good deal
October 30, 2016

Calculus AB
A = .5 b h but b = h A = .5 b^2 dA = .5 * 2 b db dA/dt = 2 b db/dt = 14 db/dt
October 30, 2016

Calculus AB
0 = 0 + Vi(4) - 4.9 (16)
October 30, 2016

Calculus AB
potential energy at 40 m = m g h = 9.8 m *40 potential energy at bottom = 0 kinetic energy at 40 m = (1/2)m *25 kinetic energy at bottom = (1/2) m v^2 so (1/2) v^2 = 9.8(40) + 12.5 v^2 = 9.8*80 + 25
October 30, 2016

physics
at top force to left from wall = Fxt vertical force from wall = 0 at bottom Force up from floor = Fzb max force to right from floor =Fxb = .4 Fzb Gravity force down at 10 meters from base = 750 N not accelerating so Fzb = 750 Fxb = .4(750) so Fxt also = .4(750) but to left ...
October 30, 2016

Physics
LOL - trick question energy is conserved if the ball is caught at the same height as it left the foot, the speed is the same. 19 m/s same horizontal component (of course) same vertical component but down not up (conservation of energy)
October 30, 2016

university physics
If it was at rest and there is no EXTERNAL force then: total x momentum = 0 total y momentum = 0
October 30, 2016

US History
State names usually have some historical significance, named after a native American chief or tribe (eg Massachusetts) or Historical Leader (Viginia for virgin queen Elizabeth or Pennsylvania for William Penn etc) or place where some settlers came from (New Whatever)
October 30, 2016

Physics
1 cm^2 = 10^-4 m^2 delta L = L F/(EA) .005 = 20 /(E*10^-4) E = 4*10^7 Pascals Think material is like rubber or you have a typo.
October 28, 2016

Algebra
worker 1 does job in x hours worker 2 does it in x+1 hours worker 1 is x hr/job or (1/x) jobs/hr worker 2 is x+1 hr/job or 1/(x+1) jobs/hr time for both together is two hr so [(1/x)jobs/hr + 1/(x+1) ]2hr = 1job 1/x + 1/(x+1) = .5 (x+1) + x = .5 x(x+1) 2x + 1 = .5 x^2 + .5 x .5...
October 28, 2016

Calculus
first do x components 3(-3) + 2(5) = -9 + 10 = 1 now y components 3(7) + 2(1) = 21 + 2 = 23 < 1, 23 >
October 28, 2016

Math practice test
The one on the lower left :)
October 28, 2016

Math
girls = g boys = 1.25 g g + 1.25 g = 450 2.25 g = 450 g = 200 then boys = 250 so there are 50 more boys than girls
October 28, 2016

Physics
I guess the wires have equal area A delta L = L * F/(EA) same for each so F/E must be the same for each F1/4 = F2/2 F1 = 2 F2 now moments about distance x from left where m is hung F1 * x = F2 (1.5-x) 2 F2 x = F2(1.5-x) 3 x = 1.5 x = .5 meters
October 28, 2016

math
one electrician would take 18 * 35 = 630 days so 28 electricians would take 630/28 = 22.5 days
October 28, 2016

Algebra
yes, difference is 1/8 or .125
October 28, 2016

physics
v = omega r = 3 so omega = 3/2.2 I = m r^2 = 46 * 2.2^2 L = I omega = 46 * 2.2^2 * 3/2.2 = 46 * 2.2 * 3
October 28, 2016

physics
change in rad/s = 1150 revs/min /1s = 1150 rev/min * 1 min/60 s * 2pi rad/rev /1 s
October 28, 2016

Biomechanics
h = 0 + 2.5 t - 4.9 t^2 0 = 0 +2.5 t - 4.9 t^2 4.9 t^2 - 2.5 t = 0 t (4.9 t - 2.5) = 0 t = 2.5/4.9 at max height, half that time h = 2.5(1.25/4.9) - 4.9(1.25/4.9)^2
October 28, 2016

history
yes, more people allowed to vote = more democracy
October 27, 2016

Chemistry
C2H2 is 26 g/mol (2*12 + 2*1) so 23/26 mols twice that many mols H20 at 18 g/mol (46/26)18 = 31.8
October 27, 2016

Chemistry
we need 3 mol of C for each of SiO2 we do not have them so only 3.6/3 = 1.2 mol of SiO2 reacts with 3.6 of C that has 2.4 mol of O or 2.4 mol of CO
October 27, 2016

math
1.20 * 88,000
October 27, 2016

math
n n+1 n+2 n+3 ------ add 4n+6 = 5 n n = 6
October 27, 2016

math
the volume of anything pointy at the to with straight sides is area of bottom * height / 3 1.476^2 * 10^6 * 2.17 +10^2 / 3 about 1.0 *10^8 but use calculator
October 27, 2016

Math (Derivative)
f(x+h) = x+h - 1/(x+h) f(x) = x - 1/x -------------------subtract h - 1/(x+h) + 1/x divide by h 1 - 1/(xh+h^2) + 1/xh 1 +[ - xh +xh+h^2]/(x^2h^2+xh^3) 1 + h^2/(x^2 h^2 + x h^3) 1 + 1/(x^2 + xh) let h --->0 1 + 1/x^2
October 27, 2016

physics
I = m r^2 omega = v/r I omega = m v r = 1400 * 28 * 116
October 27, 2016

Physics
momentum before = 45(3.4)+46(4) momentum after = (91)v so 91 v = 45(3.4)+46(4)
October 27, 2016

physicsforce * time = change of mpmentum (called impulse)
F (1.17) = 40.2(-1.84) ON her so she pushes the wall (Newton's third law) equal and opposite (40.2)(+1.84)/1.17
October 27, 2016

Math (Limits)
so put in ln .01 and ln .00001 etc or say j = ln z e^j = z e^j = 0 + a little e^-oo = 1/e^oo --->0 + a little
October 27, 2016

physics
No way I am going to just say what the answer is. You have to know and it is in your text or in any online definition of mechanical work done. Try to answer.
October 27, 2016

math
89 is a prime number. Therefore you can not do better than simply 89/100
October 27, 2016

Math
0 = 16 t^2 - 112 t - 480 0 = t^2 -7 t - 30 0 = (t-10)(t+7) t = 10 the other root was before it was launched
October 27, 2016

Math (Fraction Word Problem)
(3/5) / 2 = 3/10 is exactly the same as (3/5)(1/2) = 3/10 multiplying by 1/2 is dividing by 2 ================================== details: (3/5) / 2 multiply by 5/5 = 5(3/5)/[5*2] = 3/10 or (3/5)(1/2) multiply by 5/5 3/10
October 27, 2016

math
18000 = (250/2) h so h = 144 now you can find length of OW or IA easily as hypotenuse of right triangle of height 144 and base 25 call that center intersection C triangle OIC is similar to triangle WAC (isoceles with same top angle) so all sides are in the same ratio of 100/...
October 27, 2016

time speed and distance
distance: a t (a+b)(t-p) (a+2b)(t-p-x) all the same :) at = at + bt -ap -bp so bt = ap + bp at = at -ap -ax+2bt-2bp-2bx (a+2b)x = -ap+2bt-2bp x = (-ap+2bt-2bp)/(a+2b) = (-ap+2ap +2bp-2bp)/(a+2b) = ap/(a+2b) whew !
October 27, 2016

Mathematics
http://davidmlane.com/hyperstat/z_table.html
October 26, 2016

Algebra 1
yes
October 26, 2016

physics
They are running together at the same velocity. ZERO You and the hunk of earth you are on are zooming through space. What is your velocity relative to your chair if you are sitting quietly on it?
October 26, 2016

Physics
a = (8-0)/5 = 8/5 m/s^2 F = m a = 150 * 8/5 = 240 Newtons
October 26, 2016

Typos?
impulse = change of momentum = 8 (2 - -2) = 8*4 = 32 kg m/s none of above, even units are no impulse which is force times time - Newton seconds or momentum change kg m/s
October 26, 2016

Physics
+ 2 to - 2 = 4 8*4 = 32
October 26, 2016

oceanography
(1/2)(1/2)(1/2) = 1/8 so 70/8 grams
October 26, 2016

wrong salt percent
Seawater is about 3.5 not 35 percent salt .035 * 1000 = 35 grams salt and 1000 - 35 grams H2O
October 26, 2016

Math
You are welcome.
October 26, 2016

Math
yes, it is not only irrational but imaginary yes, the second one is rational You can always write a number with repeating decimals as a ratio of whole numbers
October 26, 2016

Physics (Mechanics)
do it for 1/4 of mass on one tire F = m v^2/r = mu m g where m = 905/4
October 26, 2016

Geography
Migration means something else entirely to me. When I hear the word I do not think of permanent immigration or emigration but of the old as the human race tension between settled city and town and farm dwellers and tough herders and hunters following the seasons and their game...
October 25, 2016

Physics
a = drop in potential energy = m g h b = gain in kinetic energy = (1/2) m v^2 work done by friction = a - b
October 25, 2016

Algebra 1
just subtract, term by term 4 x^3 2 x^2 2 x 0 4x^3 + 2 x^2 + 2 x 2 x (2 x^2 + x + 1)
October 25, 2016

Math
10 (0.1 x) = 10 (6550) so x = 65,500
October 25, 2016

Math Help
5^5/5^2 = 5^5 * 5^-2 a^b *a^c = a^(b+c) so we have 5^(5-2) = 5^3 yes
October 25, 2016

Math Help
yes ANYTHING^0 = 1
October 25, 2016

Math
35000 = a (1.07)^6 so a = 35000 / (1.07)^6
October 25, 2016

maths
6.35228 to one figure should this be 6 or 7 ? well 3 is less than five so 6 to two figures should this be 6.3 or 6.4? well 5 anything is more than halfway to the next digit so 6.4 to three figures should this be 6.35 or 6.36? well 2 is less than 5 so 6.35 to four figures ...
October 25, 2016

Math generic rectangles
this is to get 7 * 12 one rectangle is 7 by one and the other is 7 by 11. They attach together to get 7 by 12 but it is easier to multiply 7 by 1 and 7 by 11 than to multiply 7 by 12 directly. It is really just the distributive property a(b + c) = ab + ac
October 25, 2016

physics projectile
Oh, range d = 20 cos 30 * 20 = 400 * .866
October 25, 2016

physics projectile
horizontal problem: u = 20 cos 30 the whole time d = u T vertical problem: Vi = 20sin 30 = 10 v = Vi - g t at top v = 0 g t = 10 t = 10/9.81 or about one second to top time of flight = 2t = about 2 seconds h = Vi t - 4.9 t^2 = 10(1) - 4.9 = about 5 meters
October 25, 2016

Physics Help!
initial x momentum = .46 m initial y momentum = 0 final x momentum = .37 m cos 37 + v m cos T final y momentum = .37 m sin 37 - v m sin T so .46 = .37 cos37 + v cos T and .37 sin 37 = v sin T
October 25, 2016

Physics
how high was she above the bottom of the swing? h = 30 (1-cos 37) m g h = (1/2) m v^2 = initial Pot energy = final kinetic energy 2 * 9.81 *30 (1-cos 37) = v^2 ================================ add (1/2)(4^4) to initial energy for part 2
October 24, 2016

Physics
Ke up top = 1/2*.25 *225 gain of Pot energy = .25*9.81*1.2 work input = (1/4)(2 pi *.6)*30 so sum of those 3 energies = (1/2)(.25)v^2
October 24, 2016

sorry
yes
October 24, 2016

Math
I bet you mean: 3x/(x^2-x) which is 3/(x-1) the denominator is zero if x = 0
October 24, 2016

Math
k x^2 -3k x - 2 = 0 a = k b = -3k c = -2 look at b^2 - 4 a c look at parabola y = 9k^2 + 8 k must be 0 or + for 0 k (9k+8) = 0 k = 0 or k= -8/9 between them, y is negative SO k</= -8/9 or k>/=0
October 24, 2016

Math
(x+5)/(y+5) = 2/3 (x-5)/(y-5) = 3/7 ------------------ ------------------ 2 y + 10 = 3 x + 15 3 y - 15 = 7 x - 35 ------------------------ ------------------------ 3 x - 2 y = -5 7 x - 3 y = 20 ---------------- ----------------- 9 x - 6 y = -15 14 x -6 y = 40 ----------------...
October 24, 2016

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