Tuesday
July 28, 2015

Posts by damon


Total # Posts: 21,555

Math
I would say that y = x - 8 then I would say -3x - 2(x-8) = 16 I would solve that for x and use that x to go back and find y
July 28, 2015

Physics
3.9/2 = 1.95 left of pivot --- right of pivot 50(1.95) = 27 x + 35(1.95) 27 x = 15(1.95) x = 15(1.95)/27 to the right of pivot
July 28, 2015

Physics
.28 F = 98
July 28, 2015

Algebra
maybe you mean 5^4 - (8x)^2 = 0 ?????? that would be 25^2 - (8x)^2 =0 (25 - 8x)(25+8x) = 0 8x = 25 or 8x = -25
July 27, 2015

pre-calculus
112.5 = 90 + 22.5 ah ha, 22.5 is half of 45 we will be able to do this with half angle formulas first: sin 122.5 = sin(90+22.5) = sin 90 cos 22.5 + cos 90 sin 22.5 = cos 22.5 + 0 so we want cos (45/2) cos 45/2 = sqrt[ (1+cos 45)/2] = sqrt [ (1 +1/sqrt2)/2 } = sqrt [ (1 + sqrt ...
July 27, 2015

Integral calculus
h^2 = 2 x^2 2 h dh/dx = 4 x dh/dx = 2 x/h dh/dt = dh/dx * dx/dt = 2 (x/h) dx/dt but x/h = 1/sqrt 2 so dh/dt = sqrt 2 * dx/dt ---------------------- but more simply h = x sqrt 2 dh/dx = sqrt 2
July 25, 2015

Physics
total contact area = 4 * .217 * .179 = .155 meters^2 total force = gage pressure * area = 176357*.155 = 27,401 Newtons weight It might be interesting to also find the mass in kilograms assuming this all happens on earth 27,401/9.81 = 2793 Kg mass (heavy car)
July 24, 2015

Math
whoops (x+5)(x-2) (y^3+5)(y^3-2)
July 23, 2015

Math
I personally would say x = y^3 then it is x^2 + 3 x - 10 (x-5)(x+2) now go back (x^3-5)(x^3+2)
July 23, 2015

calculus
obviously 2 r </= 12 volume = pi r^2 h =1000 then pi r^2 = 1000/h but h</= 11 so pi r^2 >/= 1000/11
July 22, 2015

Physics
http://www.mathpages.com/home/kmath114/kmath114.htm u + 2 U
July 22, 2015

Math
find how many minutes until one is left. That one leaves immediately if the first ones left at t = 0 a(n+1) = (1/2)A(n) a(1) = 256 a(N) = 1 an = a1 r^n-1 1 = 256 *.5^(n-1) .5^(n-1) = 1/256 (n-1) log .5 = log (1/256) n-1 = 8 n = 9 so 9 * 5 min = 45 min if the first ones left at...
July 22, 2015

Physics
suspect you mean 30 south of west momentum east 7900*5 - 1650*20 cos 30 momentum south 1650*20 sin 30 new mass = 7900 + 1650 new mass*speed east = old momentum east new mass* speed south = old momentum south
July 22, 2015

Math Check
x^2+ x(6)^1/2+3=x^2 +3 makes no sense at all. 6^(1/2) is not zero
July 22, 2015

Physics
T = our unknown angle theta angular acceleration = alpha = d omega/dt I = (1/2) M R^2 FF = friction force up slope FF * R = torque so FF * R = (1/2) M R^2 * alpha FF = (1/2)M R alpha R omega = no slip velocity R alpha = no slip acceleration = a so FF = (1/2) M a F = m a F = M ...
July 21, 2015

Algebra1
of course we could have short cut that by saying 9 (x-8)^2 = y-8 then (x-8)^2 = (1/9)(y-8) but best do the whole completing the square process.
July 20, 2015

Algebra1
If it is indeed y = 9 (x-8)^2 + 8 then y = 9 (x^2 - 16 x + 64) + 8 y = 9 x^2 - 144 x + 576 + 8 y = 9 x^2 - 144 x + 584 then x^2 - 16 x + 64 8/9 = y/9 x^2 - 16 x = y/9 -64 -8/9 x^2 - 16 x + 64 = y/9 -64 -8/9 + 64 (x-8)^2 = y/9 -8/9 = (1/9)(y-8) vertex at (8,8)
July 20, 2015

not a parabola
Need an x^2 somewhere perhaps y = 9 (x-8)^2 + 8 or something?
July 20, 2015

math
3^2 * 6 = 9*6 = 54
July 20, 2015

math
area is proportional to scale squared volume is proportional to scale cubed
July 20, 2015

physics
10 = (1/2)(.4) t^2 solve for t v = 0 + .4 t
July 20, 2015

physics
v = 30 - a (75) assume you mean 1.5 km or 1500 meters 1500 = 30 (75) - .5 a (75)^2 solve for a then go back and get v at 75 seconds
July 20, 2015

physics(kinematics)
You are welcome. Actually that was fun :)
July 19, 2015

physics(kinematics)
me too :)
July 19, 2015

physics(kinematics)
we agree !
July 19, 2015

physics(kinematics)
v = Vi - 8 t x = Xi + Vi t - 4 t^2 20 = Xi + Vi (4) - 4(16) 20 = Xi + 4 Vi - 64 Xi + 4 Vi = 84 so Vi = (84-Xi)/4 16 = Vi - 8 t 16 = (84-Xi)/4 - 8 t (eqn 1) 4 = Xi + [(84-Xi) /4] t - 4 t^2 (eqn 2) from eqn 1 64 = 84-Xi - 32 t so Xi + 32 t = 20 Xi = (20 - 32 t) substitute that ...
July 19, 2015

college chem
Na ---- 23 g/mol Cl ---- 35.5 g/mol so NaCl 58.5 g/mol so 42.6/58.5 = .728 mols .728/1.58 = .461 mol/Liter
July 19, 2015

how exasperating !
Oh my :(
July 19, 2015

calculus
sketch it of course where does y = 2x hit y=6/x? 2 x = 6/x x^2 = 3 x = sqrt 3 then y = 2 sqrt 3 so from x = 0 to x = sqrt 3 integrate y = (2 x-.5 x) = 1.5 x 1.5 x^2/2 .75 ( 3-0) = 2.25 then where does y = .5 x hit y = 6/x? .5 = 6/x^2 x^2 = 12 x = 2 sqrt 3 so integrate y = (6/x...
July 19, 2015

Physics
.... and if you have a physics question type PHYSICS, not Blue bells....,
July 19, 2015

blue bells model school
The momentum does not change but the balls are together during the collision so initial ke = (1/2) m V1^2 = total energy initial momentum = m V1 final momentum = (n+1)m V2 so V2 = V1/(n+1) so ke during collision = (1/2) (n+1)m V2^2 = (1/2) (n+1)m V1^2/(n+1)^2 = (1/2)m V1^2/(n+...
July 19, 2015

Thokozwayo secondary school
So I can talk to my neighbors.
July 19, 2015

Physics
Jai showed you how to do this type of problem below. All your problems are really the same and are solved the same way. In other words if you do what Jai said, you can do them all. We are not here to do them all for you. http://www.jiskha.com/display.cgi?id=1437267116
July 19, 2015

math
DRAW IT ON A GRAPH ! square in quadant 3 or 4 diagonals hit at (2,-2) or (-2,-2) that is a and d NOT B or C
July 18, 2015

math
+1 -2 +3 -4 +5 .....+99 -100 = +1 +3 +5...... +99 -2 -4 -6...... -100 --------------------- ADD -1 -1 -1 ..... -1 :) LOOKS LIKE AROUND -50
July 18, 2015

math
you left the lower limit out so I assume 0 sum of all integers from -9 to +9 looks like zero to me so 4 pm
July 18, 2015

Algebra
LOL - thanks
July 18, 2015

Algebra
The key is "rounded to 82" :)
July 18, 2015

Algebra
Well, try 49 :) 49 +4*90 = 409 409/5 = 81.8 rounds to 82 so ok try 48 48 +4*90 = 408 408/5 = 81.6 rounds to 82 so ok try 47 47 + 4*90 = 407 407/5 = 81.4 no good
July 18, 2015

Algebra
( a+b+c+d+e)/5 = 82 a+b+c+d+e = 410 but 90*4 = 360 so he got at least 50
July 18, 2015

math
500/9 = 55.5 so there are 55 from 9 to 495 j = 55 500/7 = 71.4 so there are 71 from 7 to 497 k = 71
July 18, 2015

Math 115 Statistics
draw a box or matrix with your 36 possibilities make an x for win, an o for lose(3,4,6) 0 1 2 3 4 5 6 1 x o o x o x 2 o o x o x x 3 o x o x x x 4 x o x x x x 5 o x the rest x 6 number of o s = 10 so 10/36
July 18, 2015

Math URGENT!!!
10/30 * 9/29 * 8/28
July 18, 2015

calculus
dM/dt = -k M separate variables, M left, t right dM/M = -k dt integrate ln M = -k t + c note e^log a = a ao e^ln M = M = e^(-kt+c) = e^-kt e^c or since e^c is some constant call it C M = C e^-kt note that when t = 0 e^-kt = 1 so C = initial amount so here M = 100 e^-kt
July 17, 2015

physics
good answer.
July 17, 2015

maths
f-5 = 3(s-5) f + 10 = 2(s+10) ---------------- -15 = 3(s-5) - 2(s+10) -15 = 3s - 15 -2s -20 20 = s then f-5 = 60 -15 f = 50
July 16, 2015

geometry
(8/6)(12+12+6)
July 16, 2015

geometry
Pure luck ! You are welcome :)
July 16, 2015

geometry
ah, I think 155 / C
July 16, 2015

calculus
dT/dt = -k (T-38) try dT/(T-38) = -k dt ln(T-38) = -k t T-38 = ce^-kt T = 38 + ce^-kt when t = 0, T =75 75 = 38 + c c = 37 so T = 38 + 37 e^-kt at t = 30 , T = 60 so 60 = 38 + 37 e^-30 k 22/37 = .595 = e^-30 k ln .595 = -.52 = -30 k so k = .0173 and T = 38 + 37 e^-.0173 t you ...
July 16, 2015

Alebra 2
law of cosines c^2 = a^2 + b^2 - 2 a b cos angle
July 16, 2015

Stats
first pick p anchovies = 1/12 p not anchovies = 11/12 second pick you now only have 11 toppings one of which is anchovies p anchovies = 1/11 p not anchovies = 10/11 11*10/(11*12) = 10/12 = 5/6 p neither anchovies =
July 16, 2015

Math
We want y = m x + b ? solve for y 3 y = 2 x - 6 so y = (2/3) x -2 so m = 2/3 , b = -2
July 16, 2015

Math
slope = 4162 but when t = 10, n = 45400 so n - 45400 = 4162 (t-10) ----------------------------- n at t = 19 n = 45400 + 4162(9)
July 16, 2015

Math
slope = slope (y-9)/(x-1) = (19-9)/(3-1) = 5 you can do the rest
July 16, 2015

Math
12 y = 15 x - 1 y = (15/12) x - 1/12 y = (5/4)x - 1/12
July 16, 2015

Geometry
180-45
July 16, 2015

Physics
If Fx is on a graph, you need the area under the curve from x = 0 to x = 3
July 15, 2015

Physics
work done = integral Fx dx from 0 to 3 calculate that then Ke final = Ke initial + work done
July 15, 2015

Physics
assume you mean dot or scalar product A dot B = |A| |B| cos theta so here cos theta = .5 cos^-1 0.5 = 60 degrees
July 15, 2015

Calculus Partial Derivatives
x y z = k sum = s = x + y + z ds = ds/dx dx + ds/dy dy + ds/dz dz = 0 for max or min but ds/dx = ds/dy = ds/dz = 1 so ds = dx + dy + dz = 0 so max when dx = -dy - dz but x = k/(yz) dx/dy = -kz /(yz)^2 dx/dz = -ky /(yz)^2 so dx = -[-kz/((yz)^2 ]dy - [-ky/(yz)^2]dz so k y = k z ...
July 15, 2015

precalc
well, if you are not allowed to use calculus you must complete the square to find the vertex of that parabola. 16 t^2 - 48 t -20 = -h t^2 - 3 t - 1.25 = -h/16 t^2 - 3 t = -h/16 + 1.25 t^2 - 3 t + 9/4 = -h/16 + 3.5 (t - 1.5)^2 = - 1/16 ( h - 56) so at peak t = 1.5 and h = 56...
July 12, 2015

sjrkps
By the way, if you post a physics question say physics, not sjrkps so you get a physicist.
July 12, 2015

sjrkps
v = Vi + a t v = 0 + .8 m/s^2 * 20 s = 16 m/s
July 12, 2015

math
but much more fun my way :)
July 12, 2015

math
x^2 = tan^2 +2 tan sin + sin^2 y^2 = tan^2 -2 tan sin + sin^2 x^2-y^2 = 4 tan sin = 4 sin^2/cos ____________________________________ x y = tan^2 -sin^2 = sin^2/cos^2 -sin^2 = sin^2/cos^2 - sin^2 cos^2/cos^2 = [sin^2 / cos^2] [1-cos^2] but 1 - cos^2 = sin^2 so = sin^4/cos^2 so ...
July 12, 2015

physics
weight = 320+ 4*15 + 500 + 750 + 1000 = total force up moments around one end Ff=force up from floor at far end Fn = force up at near end 320(1.2)-Fn*.3+30*.3+500*.4+750*1.2 +1000*2 +30*2.1-Ff*2.1 = 0 but Fn = (total force up - Ff)
July 12, 2015

Physics
V = Vi e^-(t/RC) .1 = e^-(10/10C) = e^-(1/C) ln .1 = -1/C
July 11, 2015

Physics
but the boat is also being pushed by the propeller m = 60 + 500 = 560 kg
July 11, 2015

physics
You are welcome.
July 11, 2015

physics
6000 Pascals is 6000 Newtons per square meter. Multiply that by the area of the wall in square meters to get the force in Newtons. The density of water is about 1000 kg /m^3 so the weight of a cubic meter of water is about m g = 1000 * 9.81 = 9810 Newtons so a column of water ...
July 11, 2015

physics
k Q1Q2/d^2 plug and chug
July 11, 2015

physics
Hey, have you bothered to try these yourself?
July 11, 2015

physics
You hear the difference frequency. You want it to be zero. So loosen it more :)
July 11, 2015

physics
find the frequency from the wavelength lambda = c T = c/f then energy = Lank constant * frequency
July 11, 2015

math
8 y = -5 x - 5 1.6 y = -x - 14 slope of first = -5/8 slope of second = -1/1.6 which is -5/8 therefore, no, they have the same slope and are either parallel or identical.
July 11, 2015

Math
2 L + 2 w = 80 or L + w = 40 L w = 300 so w = 300/L so L + 300/L = 40 L^2 - 40 L + 300 = 0 (L-30)(L-10) = 0 try L = 30 and w = 10
July 11, 2015

math
LOL - close enough, a short lunchtime walk.
July 11, 2015

math
MIT, Ocean Engineering. BSc in Physics but went back later for engineering doctorate and taught engineering.
July 11, 2015

math
Anyway, find the total time for the round trip by adding the time out and the time back. Then divide 240 miles by the time in hours
July 11, 2015

math - typo?
Well did he go 60 or 40 on the way back?
July 11, 2015

physics
constant horizontal speed = 22 cos 45 so time to fence = t = 100 /(22 cos 45) so how high is it at time t? h = initial height assume 0 + [ 22 sin 45] t - (1/2)(9.81) t^2 That gives you h in meters. Convert to feet to see if it is higher than five feet.
July 11, 2015

Algebra?
huh ? multiply the side length of a square by four to get the perimeter.
July 11, 2015

Career choice advice needed
I clicked on this only because the title was in Nederlands (of Afrikaans). It would be wise to put the subject in the title so that you get a teacher who knows something about the subject (I really do not, particularly in South Africa)
July 11, 2015

physics
every second a volume of .5 m * .01 m^2 = .005 m^3 comes out of the pipe. 2700 kg/m^3 * .005 m^3/second = 13.5 kg/s
July 10, 2015

algebra
x, x and (x+5) 3 x + 5 = 26 so 3x = 21 x = 7 x = 7 x+5 = 12
July 10, 2015

st joan of arc
tan 48 = height of building/60 tan 56 = height of top of antenna/60 if you want the height of the antenna itself, subtract.
July 10, 2015

Physics
7.9/2 = 3.95 so center of plank is 3.95 from outer end which is 3.95 - 3.5 = .45 inside the edge of the platform so for equilibrium 130 (.45) = 31 x x = 1.89 out from edge
July 9, 2015

Physics
k Q1 Q2 / r^2 note r^2 not r so 1. yes 2 no 3 no 4 yes if you mean 1/r^2 5 not necessarily, Like charges repel.
July 9, 2015

Physics - what ?
equation for what? Did you try to copy and paste something? That will not work here.
July 8, 2015

math (algebra)
r = 1/d r = 1/(2r) r^2 = 1/2 pi r^2 = area = pi/2
July 8, 2015

Calculus
f(x) = |x-2|
July 8, 2015

Calculus
divide top and bottom by x (5 x^2 + x - 1)/3
July 8, 2015

david college
I would not have noticed this if Ms. Sue had not said it was Physics. I never took David College.
July 8, 2015

david college
The charge is the same on each of them. Where else would the electrons on the low side of the top one come from but the high side of the low one :) C = Q/V for each and the voltages add so 100 volts = V1 + V2 100 = Q1/C1 + Q2/C2 but Q2=Q1 = Q so 100 = Q/C1 + Q/C2 = Q (C1+C2)/...
July 8, 2015

Physics
T is tension if the slope of the plane is 32 degrees component of weight down plane = 10 (9.81) sin 32 which is trying to accelerate the mass down the slope so if acceleration up slope is a then T - 98.1 sin 32 = 10 a now the hanging mass force down = mg - T 98.1 - T = 10 a ...
July 8, 2015

No figure
This is kind of challenging without the figure but all you really need is F = m a and weight = mass * local gravity
July 8, 2015

physics
force, direction, distance from A F , up (assumed) , x (unknown) 2500 , down , 0 4000, up , 8 10,000, down , 12.5 3000, up , 21 3500 , down , 25 sum of forces up = 0 so -2500+4000-10000+F+3000-3500 = 0 F -5500 = 0 so F = +5500 up sum of clockwise moment = 0 about A 2500*0 -...
July 8, 2015

maths
so those opposite angles are 130/2 = 65 sum of all the angles is 360 so 130 + 2 theta = 360 theta = 115 so two angles of 65 deg and two angles of 115 degrees
July 8, 2015

maths
90-32
July 8, 2015

  1. Pages:
  2. 1
  3. 2
  4. 3
  5. 4
  6. 5
  7. 6
  8. 7
  9. 8
  10. 9
  11. 10
  12. 11
  13. 12
  14. 13
  15. 14
  16. 15
  17. Next>>

Members