Sunday
February 1, 2015

Posts by Damon


Total # Posts: 20,453

Science
The jellyfish, which I suspect is actually a squid (I gather your teacher is not a fisherman), moves forward as the water moves aft. I suppose you could say that this is due to the third law (action---> equal magnitude opposite direction reaction). However I consider this a...
February 1, 2015

Physics
F = k Q1 Q2 /d^2 due to right one, +force because opposite sign due to middle one, -force because of same sign F = k(10^-6)(10^-6)(65) [ 95/1.2^2 -48/.6^2 ]
January 31, 2015

Physics
force up = 25 sin 25 force down = 5(9.81) normal force = 5(9.81) - 25 sin 25 pull force = 25 cos 25 back friction force = 4 so 25 cos 25 - 4 = 5 * a
January 31, 2015

Physics
force up from left wire = 106 sin 5 force up from right wire also 106 sin 5 total force up = 212 sin 5 = weight down = m g = 9.81 m m = (212/9.81)sin 5
January 31, 2015

physics
u = speed * cos 27.1 7.72 = speed *cos 27.1 * t where t is time in air h = Hi + Vi t - (1/2) g t^2 0 = 0 + speed*sin 27.1 * t - 4.9 t^2 but we know t = 7.72/(speed*cos 27.1) call speed s 0 = 0 + 7.72 tan 27.1 - 4.9*7.72^2/(s^2cos^227.1) solve for s do it again for s = 1.05 s
January 31, 2015

math
j = dan + 30 dav = 3 j j + dan + dav = 400 (dan+30) + dan + 3 (dan+30) = 400 5 dan + 120 = 400 5 dan = 280 dan = 56 j = dan + 30 = 86 dav = 3 j = 258
January 31, 2015

arithmetic not vector calculus
p = 3000 q1 + 12000 q2 - 5000
January 31, 2015

math
It moved up from -7 to +7 so it could be a translation straight down. It could also be a reflection about the x axis, but the question asks for a "translation".
January 31, 2015

georgia state history
salt or pepper?
January 31, 2015

Trigo
Angle ABP = 54 - 46 = 8 Angle PBQ = 90- 54 = 36 (note used 54) so Angle PAB = 180 - 8 - 36 = 136
January 31, 2015

math
huh? 78/100 = 39/50
January 31, 2015

algebra
n = o + 9 o + (4/5) n = n so n - 9 + 4 n/5 = n 4 n /5 = 9 4 n = 45 n = 45/4 o = 45/4 - 36/4 = 9/4 ============================ now check n = o + 9 = 9/4+36/4 = 45/4 yes o + (4/5) n = n 9/4 + (4/5)(45/4) = n ? 5*9/4 = n ? 45/4 = n yes
January 31, 2015

algebra
Just did that, see above
January 31, 2015

Maths Problem
[ a+b ]/2 = 81 so a+b = 162 but b = a+26 so 2 a + 26 = 162 2 a = 136 a = 68
January 31, 2015

physics - question incomplete
Force on what ? do you mean in a row, each 20 cm from the previous ? In general F = k Q1 Q2/d^2 toward each other if opposite sign repel each other if same sign
January 31, 2015

Natural science
Hummm, my thing is physics so I am not sure. However I would Google pistel and stamen yes, try this: http://urbanext.illinois.edu/gpe/case4/c4facts1a.html
January 31, 2015

MATHS
http://www.jiskha.com/display.cgi?id=1422706001
January 31, 2015

Calculus
Do it Reiny's way (but mine is more fun)
January 31, 2015

Calculus
2.44 + .0053535353 ....... 2.44 + (1/100)(.53535353 .... ) .53535353... = .53 + .53/100 + .53/100^2... = a + a r + a r^2 + a r^3..... where a = .53 and r = .01 sum of that infinite series = a/(1-r) so .53 /(.99) = 53/99 so we have 2.44 + (1/100)(53/99) (1/100)( 244 + 53/99) I ...
January 31, 2015

Statiatics
4/5 is chance wrong problems are independent so (4/5)(4/5) = 16/25
January 31, 2015

math
independent probabilities (1/42)(1/47)
January 31, 2015

Trigo
you went a total of 160 straight north you went 40 east draw that on a graph, 40 right, 160 up the angle between north and east is 90 deg so you want the hypotenuse of that right triangle.
January 31, 2015

Trigo
y distance = 90 + 70 = 160 x distance = 40 want hypotenuse d = sqrt (40^2 + 160^2)
January 31, 2015

Calculus
e^.2x = 75/(30*16) .2x ln e = ln (75/480) but ln e = 1 .2 x = ln (75/480) ======================= 8^tan x * ln 8 * (1/sec^2 x)
January 31, 2015

Physics - must know all masses
insufficient information
January 30, 2015

Physics
F = G Mearth Moject / r^2 F1 = G Mearth m/6400^2 F2 = G Mearth m/6780^2 so F2/F1 = (6400/6780)^2 = 0.891
January 27, 2015

math
150 C (95-0) = 21 (heat of fusion of ice) where C is heat capacity of iron about 0.450 J/ g deg c
January 27, 2015

Math - Problem solving
last year = x this year = x+20 x = 0.75(x+20)
January 27, 2015

COMBINED OPERATION ON FRACTIONS
(3/5)j +(3/4)(2/5)j + 3 = j
January 27, 2015

physics
both angular and linear momentum are conserved. The center of gravity of the system is height: h (m+m) = m x + m (L/2) and it is moving at speed Ucg (m+m) = u m then of course you have the rotation about the cg
January 27, 2015

Math
the area of the base is easy w*L if the height is h then two of the slope triangles have base w and height along the slope of sqrt(h^2 + L^2/4) so the sum of those two triangle areas is w *sqrt(h^2 + L^2/4) similarly the sum of the other two triangle areas is L * sqrt (h^2 + w...
January 27, 2015

Math / Algebra
I agree
January 27, 2015

algebra
-y = 18 * 7 y = -18 * 7
January 27, 2015

Math word problems
100 - 25 = 75 so you took 25 off every hundred In other words, 25% discount another way to do it: 160 - 120 = 40 dollars discount 100 (40/160) = 25 %
January 27, 2015

Science
If you look at the inside of a tree branch or tap maple sap you see straw like tubes that transport fluid around.
January 27, 2015

Physics - Vectors
|A| |B| cos theta = A dot B 2.2 * 10 * cos theta = 14 theta = cos^-1 (14/22) theta = 50.5 degrees
January 26, 2015

Math
x = 2log4 y log4 y = (x/2) 4^log4 y = 4^(x/2) y = 4^.5x
January 21, 2015

math
1.75 inches ( 45 miles/2.25 inches) =
January 21, 2015

physical
(1/2)m v^2 = m g h so v = sqrt (2 g h) remember that
January 21, 2015

physics
Google Millikan oil drop experiment for example: http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Ryan_McAllister/Slide3.htm
January 21, 2015

math
the absolute value of (sec x)^2 is just sec^2 x because when you square a number it is positive so we have (1/cos^2) sin / [1/sin] or tan^2 x dx = tan x - x + c
January 19, 2015

physics
calculate F = Q E do a = F/m to get a, the acceleration then plain old constant acceleration x = (1/2) a t^2
January 19, 2015

Civics
YES !!!!!
January 19, 2015

Civics
Google Marbury vs Madison
January 19, 2015

Physics
x = 2 + 3.2 t - 3.85 t^2 when is v = 0? dx/dt = v = 3.2 - 7.7 t v = 0 when t = 3.2/7.7 = .416 seconds then x = 2 + 1.33 - .665 = 2.66 If you do not know calculus, find the vertex of the original equation.
January 19, 2015

Physics
d = Vi t + (1/2) a t^2 98.3 = 29 t - 1.8 t^2 1.8 t^2 -29 t + 98.3 = 0 solve quadratic for t [ 29 +/- sqrt ( 841 - 708) ] /3.6 [ 29 +/- 11.5 ] / 3.6 = 4.86 (ignore the big time, it is on the way back :)
January 19, 2015

Civics
14 says they have the right to go to school just as other citizens do. 13 just says they are not slaves any more.
January 19, 2015

Civics
I would say 14 which does not allow sates to deny privileges to any citizens.
January 19, 2015

ap calc
(z^2)^(1/2) = z you have (x^2 - 4) dx x^3/3 - 4 x + C
January 19, 2015

Math
I am an engineering teacher not a civics teacher jeje.
January 19, 2015

Math
(4/5)(7/8) = 7/10
January 19, 2015

Algebra
s = side length x = long length 2 s + x = 1600 so x = (1600-2s) 2 s (5) + x (20) = 13,000 10 s + 20 (1600-2s) = 13,000
January 19, 2015

physics
By the way to do the second one you must know the density of the fluid. These are very strange questions. Are you sure you have copied them correctly?
January 19, 2015

physics
I do not know. All I know is the ratio of areas. 80 (pi r^2) = 1300 (pi R^2)
January 19, 2015

SCIENCE
3. An electric engineer might (1 point) Build a dam to provide a source of hydroelectric power.*** Develop new fuels to use in the next generation of fuel-efficient cars. Design a remote-controlled toy race car. Design an airplane wing that changes shape to increase stability...
January 19, 2015

Physics
at the same acceleration as (one g about 9.8 m/s^2)
January 19, 2015

physical science
------>------> = ------------> <----- ------> = 0
January 19, 2015

physics
F * d = work done by friction = initial Ke = (1/2) m v^2 F * 50 = (1/2)(750)(900) 100 F = 750 * 900 F = 750 * 9 There are harder ways of course using F = change of momentum/ time = 750*30/t then 50 = (1/2)a t^2 where a = 30/t so 100 = 30 t t = 10/3 seconds to stop a = 9 m/s^2...
January 19, 2015

Physics
56.1 mi/h = 25.1 m/s v = Vi - a t 0 = 25.1 - a t so t = 25.1/a d = (1/2) a t^2 206 = a t^2 206 = a(630/a^2) = 630/a a = 3.06 m/s^2 (negative of course)
January 19, 2015

Physics
h = (1/2) g t^2 = 4.9 (3.12)^2
January 19, 2015

Physics
d = (1/2) a t^2 194 = 6.60 t^2 solve for t then v = Vi - 6.60 t = 0 at end Vi = 6.60 t
January 19, 2015

Physics
v = Vi + a t 104/3.6 = 74/3.6 + 1.52 t
January 19, 2015

ap calc
d/dx (2x+7)) = 2 so the 1/2 gets rid of the 2
January 19, 2015

Physics
but you forgot the work done against gravity m g * 500 = .05 * 9.81 * 500 = 245 J 1450 - 245 = 1204 J so 1204 = .05 * a * 500 =============================== The second one looks ok
January 18, 2015

physics
Aaaarrrgghhhhh !!!!! Joey is right. At the top v = 0, no velocity except that of mother earth spinning on her axis and making her way around the sun. The acceleration is constant, -9.81 m/s^2 the whole time. Charlie could not possibly, any way, be more wrong. Send him to his ...
January 18, 2015

Physics
t = 4.2 T = 8 a = 5 I guess it started from a dead stop. x = (1/2) a t^2 during acceleration Vi = speed at end of acceleration = a t X = Vi T during constant speed so distance = (1/2) a t^2 + Vi T
January 17, 2015

Math
32 = 8 * 4 56 = 8 * 7 so 32 + 56 = 8 (4+7)
January 15, 2015

MATH
how much of the 40 hours he works at each job
January 15, 2015

Torque
Huh? 30 * 1.5 = 45 BUT 60 * 1 = 60
January 15, 2015

physicsss
You are welcome.
January 15, 2015

physicsss
If the velocity is constant you are correct.
January 15, 2015

Physics
work done in stopping = brake force * 75 meters (1/2) m v^2 = work done by brakes (1/2) m (93)^2 = F * 75 F = m (57.66) but F = ma so a = 57.66 that is the acceleration the tires can give you. Use it for centripetal acceleration a = 57.66 = v^2/r r = (93)^2/57.66
January 15, 2015

Physics
mu m g = m v^2/r = m omega^2 r mu g = omega^2 r omega = 2 *2pi radians/s = 4 pi rad/s mu = .4 g = 9.81 so r = .4 * 9.81 /16 pi^2 = .0248 meters = 2.5 cm
January 15, 2015

Physics
m v2/r
January 15, 2015

No picture
If you drew a picture, we can not see it.
January 15, 2015

Alegebra
Huh? how can it be even and 9 ????
January 15, 2015

physics
Without friction, the angular velocity will not change. In real fife of course it will. Even in the vacuum there is loss of kinetic energy to the bearings. However as far as the information given here, the answer is constant angular velocity forever. or at least for a very ...
January 15, 2015

Physics
Vi = 15 sin 30 = 7.5 v = Vi - gt v = 0 at top so g t = 7.5 t = 7.5/9.8 = about .77 s
January 15, 2015

Calculus POwer RUle
dy/dx = -3 k x^2 3 = -3 k (4) k = -1/4
January 14, 2015

Math
b = 2 r b - r = 24 2 r - r = 24 r = 24 b = 48
January 14, 2015

math
16 x = x^2 x^2 -16 x = 0 x(x-16) = 0 x = 0 or x = 16 y = 0 or y = 256 (0,0) and (16 , 256)
January 14, 2015

calculus
If 5x2 + y4 = -9 then evaluate d^2y/dx^2 when x = 2 and y = 1 5 x^2 + y^4 = -9 10 x + 4 y^3 dy/dx = 0 so dy/dx = -2.5 x/y^3 d^2y/dx^2=-2.5[ y^3 - 3 x y^2 dy/dx]/y^6 at (2,1) dy/dx = -2.5(2/1) = -5 so d^2y/dx^2=-2.5[1-6(-5)]/1 = -2.5 [ 31] = - 77.5
January 14, 2015

calculus
Find the slope of the graph of the relation x2y + 4y = 8 at the point (2, 1) (x^2+4)y = 8 (x^2+4)dy/dx + y (2x) = 0 8 dy/dx + 4 = 0 dy/dx = -1/2
January 14, 2015

calculus
f(x)=(x+1)^2x d/dx u^v = v u^(v-1)du/dx + u^v lnu dv/dx so f'=2x(x+1)^(2x-1) + 2(x+1)^2x ln(x+1)
January 14, 2015

calculus
x^2 + y^2 = 2 x y 2 x + 2 y dy/dx = 2 x dy/dx + 2 y dy/dx (y-x) = y-x dy/dx = 1 easier way without using calculus: x^2-2xy+y^2 = 0 (x-y)(x-y) = 0 x = y slope = 1
January 14, 2015

calculus
y = 7 x^6 cos^-1 x f' = 7[ x^6 (1/(1-x^2)) + 6x^5 cos^-1 x ] = 7 x^6/(1-x^2) + 42x^5 cos^-1 x
January 14, 2015

history
LOL - well, to start with which ? TR or FDR ? You better Google which ever president you mean because it would take all night to summarize.
January 14, 2015

science
NaCl = 23 + 35 = 58 g/mol 22/58 = .379 mol .379 mol/ .2 liter = 1.9 M
January 14, 2015

Math
Get it now. When you subtract you reverse the sign of the bottom one and add.
January 14, 2015

Math
y=-x+4 y=-2x-4 ------------- SUBTRACT these two equations 0 = -x -(-2x) + 4 - (-4) 0 = -x + 2x + 4 + 4 0 = x + 8 x = -8
January 14, 2015

Math
y = -x + 4 y = -(-8) + 4
January 14, 2015

Math
for elimination subtract as is y=-x+4 y=-2x-4 ------------- 0 = 1 x + 8 so x = -8 then get y = 8+4 = 12
January 14, 2015

Math
I did the earlier ones with elimination here is substitution y = (-x+4) so (-x+4) = -2x - 4 x = -8 then go back and get y y = -x + 4 = 8+4 = 12
January 14, 2015

Math
You are welcome.
January 14, 2015

Math
10 x - 8 y = 20 -10 x + 2 y = -20 ----------------- add 6 y = 0 y = 0 if y = 0 5 x = 10 x = 2 so the two lines intersect at (2 , 0)
January 14, 2015

calculus
1. If f(x) = ln(1 - 2x), then find f '(x) f' = [ 1/(1-2x) ]( -2) = -2/(1-2x) = 2/(2x-1) I do not understand your second function
January 14, 2015

Math
check it then 2 (9) - 5 (-7) = 53 ? yes -9 +5(-7) = -44 ? yes so it is right, why ask ? :)
January 14, 2015

Calculus
x = 15 t h = 5 t + 5 = 5(t+1) y^2=x^2+h^2 = 225t^2 + 25t^2 + 50 t + 25 y^2 = 250 t^2 + 50 t + 25 2 y dy/dt = 500 t + 50 now at t = 3 y^2 = 250(9)+150 +25 = 2425 y = 49.2 so 2(49.2) dy/dt = 1500 + 50 = 1550 dy/dt = 15.8 m/s
January 14, 2015

Math
add the two equations as is x = -10 5 y = 50 y = 10
January 14, 2015

physics
easier way work done = final (1/2) m v^2 4310 = (1/2)2520 v^2 v = 1.85 m/s ;)
January 14, 2015

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