Wednesday
October 1, 2014

Posts by Damon


Total # Posts: 18,728

physics
dv/dt = -kv dv/v = - k dt ln v = - k t + c e^ln v = v = e^(-kt +c) = e^c e^(-kt) when t = 0, v = Vo Vo = e^c e^0 = e^c so v = Vo e^-kt
August 19, 2014

physics
2 seconds rising and 2 seconds falling h = (1/2)g t^2 falling 10 = (1/2) g (4) = 2 g g = 5 m/s^2
August 19, 2014

physics
it evidently goes forward a distance 3d then back a distance 2d to end up a displacoutup to be negative. deceleration phase out to 3 d t1 = time out to 3 d v = Vi + a t1 0 = Vi + a t1 so t1 = -Vi/a 3 d = Vi t1 + (1/2) a t1^2 3d = -Vi^2/a + .5 Vi^2/a = -.5Vi^2/a d a = -(1/6) Vi...
August 19, 2014

Language Arts
I can not see your italics but suspect it is the "ing" and D is correct. http://en.wiktionary.org/wiki/present_participle
August 19, 2014

math
5 y + 7 x = 31 x y 5 y + 7 x = 29 x y well, (0,0) would work but then we would be dividing by zero in the original.
August 19, 2014

English
"His questions revealed an intelligence" seems to be the main idea so what is the rest ? http://www.chompchomp.com/terms/relativeclause.htm
August 19, 2014

english
http://www.merriam-webster.com/dictionary/tally
August 19, 2014

P.E
I figure my natural crabbiness is likely to be fatal, perhaps even to me.
August 19, 2014

P.E
Certainly
August 19, 2014

english
Let me see: He spread the rumor widely. ------> He spread the rumor most widely ?
August 19, 2014

math
There are six numbers so add them all up and divide the sum by six.
August 19, 2014

Philippine history
http://www.academia.edu/4833169/Continued_Filipinization_in_the_Late_20th_Century_The_Case_of_the_Ateneo_de_Manila_University_1968-1991
August 19, 2014

Philippine history
http://prezi.com/cfw8l09tjkas/filipinization-policy/ When the US defeated the Spanish in the Spanish American War, the Philipines ceased to be a Spanish colony and came under the US. The US made an effort to let the indigenous people take over ruling their islands replacing ...
August 19, 2014

Physics
All I can do is tell you the method. call M1 the mass of the one that is on string at 50 degrees from vertical (aI assume from vertical Then gravity force down slope is M1 g cos 50 T is up slope net force down is (M1 g cos 50 -T) same deal for M2 net force down is (M2 g cos 30...
August 19, 2014

Physics
I do not understand this geometry. Is the big one trying to drop down a 53 deg slope and the little one being dragged up a 30 degree slope or what?
August 19, 2014

Physics
The table is three football fields long and three football fields high? I bet it was 0.15 seconds actually :)
August 19, 2014

Physics
big table :)
August 19, 2014

Physics
F = 20 * 9.8 m = 50 + 20 = 70 a = F/m = 2.8 m/s^2 force on falling 20 kg mass = 20 (9.8) - T = m a = 20(2.8) so T = 140 Newtons d = (1/2) a t^2 = (1/2) 2.8 (225) = 315 are you sure you did not mean 1.5 seconds?
August 19, 2014

science
probably at least on a cell scale.
August 19, 2014

Second law of motion
Net force up = 35 - 25 = 10 Newtons F = m a m = 25/9.8 = 2.55 kg so a = 10 / 2.55 = 3.92 m/s^2
August 19, 2014

Physics
Good grief, English units, have to put mass in slugs and use seconds and pounds and feet. (Back to freshman year in 1955) change in speed = 40 miles/ hr *5280 feet/mile * 1 hr/3600 seconds = 58.7 feet per second mass in slugs = 3000 lb /32 ft/s^2 = 93.8 slugs F = change in ...
August 19, 2014

Science
north velocity = 30 (assume west wind so blowing plane east) east velocity = 40 total speed = sqrt (30^2+40^2) = 50 km/hr tan angle east of north = 40/30 angle east of north = 53.1 or about northeast by east (NExE)
August 19, 2014

Physics
F down slope = m g sin 35 a = F/m = g sin 35 = 9.8 sin 35
August 19, 2014

math
a + a r + a r^2 + a r^3 + a r^4 ....+a r^(n-1) so a r = 1.5 a r^4 = .1875 a = 1.5/r (1.5/r) r^4 = .1875 r^3 = .125 r = .5 a = 1.5/.5 = 3 so 3 + 1.5 + .75 ......
August 19, 2014

science
Huh ?
August 19, 2014

Parabola
axis of symmetry is halfway between 2 and 3 or x =2.5 to get the zeros of y at x = 2 and 3 y = k (x-2)(x-3) to get y = 6 at x = 0 6 = k (-2)(-3) k = 1 so y = x^2 -5 x + 6 (answer) check if vertex is at x = 2.5 by completing the square y -6 = x^2 - 5 x y - 6 + (5/2)^2 = x^2 - 5...
August 19, 2014

Maths
(1-e^-x) integral (1-e^-y) dy from 1 to 2 (1-e^-x) [ y + e^-y ] at 2 - at 1 (1-e^-x) [ 1 + (e^-2 - e^-1) ] (1-e^-x) [ .767 ] integrate that dx from 1 to 3 [ .767 ][ x + e^-x] at 3 - at 1 [ .767 ] [ 2 + (e^-3 - e^-1) ] [ .767 ] [ 1.68 ] 1.29 divide by area to normalize area = 2...
August 19, 2014

algebra
I do not dare because I bet you have typos. For example I would be surprised if -1^2 is not supposed to be (-1)^2.
August 19, 2014

physics
no s = -16 t^2 + 64 t If the ball left the ground with velocity + 64 ft/x then it returns to earth with velocity -64 ft/s. Your parabola is symmetrical and the vertex is at the top,
August 19, 2014

Math
Sorry, can not email to you. The word compass bearing is used correctly here. tangent of angle north from west axis = 70/145 tan^-1 (70/145) = 26 deg so bearing = 270+26 = 296 degrees clockwise from North this is approximately west north west
August 18, 2014

math
Henry, The 30 degrees is from North (the y axis), not from east (the x axis as in math convention).
August 18, 2014

math
^&%#*& mathematicians ! He flies on a HEADING of 030 east of north, NOT a bearing. You take a bearing on something, its direction from you. You sail or fly a compass HEADING. anyway East components are 90 sin 30 +150 =90 * (1/2) + 150 = 45 + 150 = 195 km east of start
August 18, 2014

math
actually the express train from Delhi to Meerut seems to go about 44 km/hr by the way: http://indiarailinfo.com/search/new-delhi-ndls-to-meerut-cantt-mut/664/0/1546
August 18, 2014

math
they approach each other at 180 km/h 75 km * (1 h/180 km) = .4167 h * 60 min/h = 25 minutes so 8:25 am
August 18, 2014

social studies
http://dictionary.reference.com/browse/xenophobia
August 18, 2014

social studies
Thank you Lexie Bowles. That was fun !
August 18, 2014

social studies
http://civilliberty.about.com/od/immigrantsrights/tp/Xenophobia-in-United-States.htm
August 18, 2014

social studies
http://en.wikipedia.org/wiki/Anabasis_%28Xenophon%29
August 18, 2014

math
50 in 125 and 30 in 90?
August 18, 2014

math
9 + 63 = 72 using rounding which happens to be exact and I also call 9 and 63 compatible numbers since adding 9 to anything is super easy.
August 18, 2014

physics
V defined as speed out of the barrel time rising = time falling so find rise time and multiply by 2 vertical problem: Vi = V sin 30 = .5 V v = Vi - 9.8 t v = 0 at top 0 = .5 V - 9.8 t so t = .5 V/9.8 and 2 t = total time aloft = V/9.8 at max height there is no vertical ...
August 18, 2014

physics
You are welcome :)
August 18, 2014

physics
if none were added dN/dt = k N number produced per second = 10 number lost per second = k n so dN/dt = 10 - k N N is maximum when dN/dt = 0 0 = 10 - k (1000) k = .01 so we know that for this fission reaction (without the inflow) dN/dt = -.01 N dN/N = -.01 dt ln N = -.01 t + C ...
August 18, 2014

probability
first red = 8/24 second blue = 4/23 so (1/3)(4/23) = 4/69
August 17, 2014

Engineering maths
outside dimensions of deck are L and W inside dimensions of deck are 30 and 22 so Area of deck = L W - 660 so L W - 660 = 480 L W = 1140 if x = deck width Length L = 30 + 2x W = 22+2x so (22+2x)(30+2x) = 1140 multiply out and solve quadratic
August 17, 2014

physics
I think they mean total acceleration up
August 17, 2014

physics
Vi = a t = 32 * 4.1 = 131 m/s at burn out h = (1/2)32 (4.1)^2 = 269 meters at burn out then v = Vi + a t at top v = 0 0 = 131 - 9.8 t t = 13.4 seconds coasting up h = 269 + 131 (13.4) -4.9 (13.4)^2
August 17, 2014

computers
Yes, http://www-03.ibm.com/ibm/history/exhibits/pc25/pc25_birth.html
August 17, 2014

computers
As I remember Microsoft
August 17, 2014

important math question
http://archives.math.utk.edu/visual.calculus/3/newton.5/
August 17, 2014

important math question
sorry, x - y / dy/dx
August 17, 2014

important math question
Newton's method for finding zeros f(x) = x^3 -x-5 pick an x in the range, say x = 2 f(2) = 1 f'(2) = 3 x^2 - 1 = 11 mark that point (2,1) and slope of 11 through it now that slope will hit the x axis at x + y / dy/dx or 2 + (-1)/11 = 1.909 now repeat again and again ...
August 17, 2014

important math question
Did you click on the polynomial calc link? You can use Newton's method. I will give you a link in a minute. Oh, no need, this next problem is in fact Newton's method. Draw a sketch f(3) = 5 Put an x at (3,5) slope ay (3,5) = -2 f(x+dx) = f(x) + slope * dx f(3 + .02) = ...
August 17, 2014

typo
1.90416
August 17, 2014

important math question
The only real root is x = 1.0416 http://www.mathportal.org/calculators/polynomials-solvers/polynomial-roots-calculator.php
August 17, 2014

trigonometry
draw a sketch cos 68 = x/43
August 17, 2014

Algebra
Every integer is a rational number because you can divide it by one.
August 17, 2014

Precalculus
at least one typo 2Z-W=(2Zx-Wx)i+(2Zy-Wy)j |2Z-W|^2=4Zx^2-4ZxWx+Wx^2+4Zy-4ZyWy+Wy^2 =4|Z|^2+|W|^2 -4(ZxWx+ZyWy)= 625 and |Z+2W|^2 =|Z|^2+4|W|^2 +4(ZxWx+ZyWy)=25 so 625+25 =5[ |Z|^2+|W|^2| ] or 130 = |Z|^2 + |W|^2 now that last one |Z+W|^2= Zx^2+2ZxWx+Wx^2+Zy^2+2ZyWy+Wy^2] = 4 ...
August 16, 2014

Precalculus
You asked for it: 2Z-W=(2Zx-Wx)i+(2Zy-Wy)j |2Z-W|^2=4Zx^2-4ZxWx+Wx^2+4Zy-4ZyWy+Wy^2 =4|Z|^2+|W|^2 -4(ZxWx+ZyWy)= 625 and |Z+2W|^2 =|Z|^2+4|W|^2 +4(ZxWx+ZyWy)=25 so 625+25 =5[ |Z|^2+|W|2| ] or 130 = |Z|^2 + |W|^2 now that last one |Z+W|^2= Zx^2+2ZxWx+Wx^2+Zy^2+2ZyWy+Wy^2] = 4 ...
August 16, 2014

mathematics
well lets see 14 23 32 41 50 could be 23 or 41
August 16, 2014

Physic - Oh well, Google might help
http://antoine.frostburg.edu/chem/senese/101/measurement/faq/indiana-jones.shtml
August 16, 2014

Physic sorry :(
LOL, can not help with this, did not see movie !
August 16, 2014

Math
ALMOST !!! sign error - dx /[(x+dx+3)(x+3) ] divide by dx -1/[(x+dx+3)(x+3) ] now let dx -->0 -1/(x+3)^2 which any calculus text will tell you is the right answer d/dx (1/u) = [bottom*d top - top d bottom]/bottom squared
August 16, 2014

Math
oh, much more fun !
August 16, 2014

Math
sqrt 2/ 4 = .35355 which is what our table and graph said
August 16, 2014

Math
no it is one quarter of the square root of 2
August 16, 2014

Math
Now that was fun but you do the next one :)
August 16, 2014

Math
sorry 1/ [2 sqrt2) multiply top and bottom by sqrt 2 to rationalize and we get (sqrt 2) / 4 as we knew all along
August 16, 2014

Math
x y 1.0 .318 0.5 .334 0.2 .345 0.1 .349 .05 .351 .02 .353 .01 .353 .001 .35351 etc which looks much like (sqrt 2 )/4 [(x+2)^.5-2^.5]/x * [(x+2)^.5+2^.5] ----------------------------------- [(x+2)^.5+2^.5] [(x+2) -2] = ------------- x [ (x+2)^.5+2^.5] = 1/ [(x+2)^.5+2^.5] which...
August 16, 2014

Math
http://www.wolframalpha.com/input/?i=%28%28x%2B2%29^.5-2^.5%29%2Fx
August 16, 2014

Math
You are welcome.
August 16, 2014

Math
By the way since this particular function is linear, constant slope, there was no need for us to take the limit to find the derivative (slope at x is slope at any x)
August 16, 2014

Math
this is the definition of the derivative f(x+dx) = 3(x+dx)-2 = 3 x + 3 dx -2 f(x) = 3 x - 2 f(x+dx) - f(x) = 3 dx divide by dx = 3
August 16, 2014

fitness
I do not know what to say :(
August 16, 2014

fitness
Having already found differing answers to these questions online, I think you better use the ones in your text book.
August 16, 2014

Algebra
2.5 * 144
August 16, 2014

fitness
Question 3 I suppose they mean the average baby.
August 16, 2014

fitness
Please post answers when you find them :)
August 16, 2014

physical
the deaths from heart, cancer and stroke, but they add to 50% which is not on your list of answers.
August 16, 2014

physical
That same site has the answer to question 2 in a link.
August 16, 2014

geometry
Must be less than 3+5 and more than 5-3
August 16, 2014

geometry
2 2 3 3 3 1
August 16, 2014

Math
by "right" do you mean "right triangle" ? If so then tan B = b/a B = tan^-1 (b/a)
August 16, 2014

calculus
Hey, you are doing great ! These last two were harder than the ones you asked for help with.
August 16, 2014

calculus
good, that is a long one :) add, then multiply, then add
August 16, 2014

calculus
3 min = 180 seconds downstream = 5 * 180 across = 12 * 180 hypotenuse = sqrt (across^2 + downstream^2)
August 16, 2014

calculus
in the x direction 6 * 1 = 6 int the y direction 2 * -4 = -8 in the z direction 0 * 1 = 0 6 + -8 = -2 see: http://www.mathsisfun.com/algebra/vectors-dot-product.html to see how to do it with |A| * |B| * cos theta
August 16, 2014

Physic
hard to say without knowing the volume. duck it in a full cup and measure the amount of water that flows over the lip.
August 16, 2014

Physics 2
Hard to say without knowing the distances... In general F = k Q1 Q2 /|R^2| iin direction of R If horizontal length = a and vertical height = h Q is lower right Q1 is lower left Q2 is upper left Q3 is upper right R is vector from Q to one of the other 3 Rx = x component of R Ry...
August 16, 2014

Algebra
I am not sure your superscript shows up on everyone's screen. 5 (14-20)^2 /2 = 5 * 36 /2 = 5 * 18 = 90
August 16, 2014

physics, mit 2.01x, mechanical engineering
If you tried to copy and paste the drawing or sketch of this truss here, it did not work because copy and paste is not allowed here. From what you said, moment of inertia of the cross section must be increased or length of section reduced assuming you are doing Euler column ...
August 15, 2014

math
how many buggies? 21 = 9 + 3 n n = 4 4*4 = 16 21 - 16 = 5
August 14, 2014

Math
1+2+3 average is (1+3)/2 = 2 2*3 = 6 check :) so I think it is (1+31)/2 = 16 16*31 = 496
August 14, 2014

math
-2 = -1/.5 so they are perpendicular, yes, C
August 14, 2014

math corrections
profit, p = revenue, r - cost, c r = revenue = 25 g c = cost = 75 so p = 25 g - 75 so if p >/= 50 then 25 g - 75 >/= 50 so you are right. It is E.
August 14, 2014

math
4.85/4 = 1.21625 = quarterly percent 11 years = 44 quarters (1.0121625)^44 = 1.7022 3,500 * 1.7022 = 5957.70 so agree. I do not see any list of staetements
August 14, 2014

mathematics
x+6
August 14, 2014

math corrections
I agree with your answer, C and have no idea why it is called incorrect.
August 14, 2014

math corrections
1, 5c 2 10 c 3, 15 c 4, 25c 5 30C 6 35 c 7 40 c 8 50 c 9 55 c 10 60 c 11 65 12 75 c 13 80 c 14 85 c 15 90 c
August 14, 2014

math
4000/7 = 571.4 so we need a little more than 571 572 will do 572 * 7 = 4004, check :)
August 14, 2014

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