Wednesday
July 29, 2015

Posts by Damon


Total # Posts: 21,565

Math
v = s^3 dv = 3 s^2 ds at s = 50 v = 125,000 dv = 3 (2500) ds = 7500(.1) = 750 100 (750/125,000) = .6 %
December 29, 2014

Calculus- Can you help me solve for dr/dt
You are welcome. Actually I am retired now :)
December 29, 2014

Calculus- Can you help me solve for dr/dt
The change of volume of a sphere with increasing radius is the surface area of the sphere times dr. Draw a picture ! In other words: dV = 4 pi r^2 dr so dV/dt = 4 pi r^2 dr/dt so here 15 = 4 pi r^2 dr/dt or dr/dt = 15 /(4 pi r^2) ---------------------- note , I am a ship ...
December 29, 2014

geomentry
Its volume is 27 times the old volume (3*3*3)
December 28, 2014

Physics
You are welcome. Remember potential is always a difference (In height, voltage, whatever).
December 27, 2014

Physics
10,000 meters the horizontal distance is irrelevant.
December 27, 2014

^Maths^
good point :)
December 27, 2014

^Maths^ typo
301 base 6 1*10^0 + 0*6^1 + 3*6^2 should be 301 base 6 1*6^0 + 0*6^1 + 3*6^2 = 109
December 27, 2014

^Maths^
By the way, I just did that by common sense. I do not know what routine you are really supposed to know. You may have a better way to shift back and forth.
December 27, 2014

^Maths^
451 base 6 1*6^0 + 5*6^1 + 4*6^2 = 1 + 30 + 144 = 175 in base 10 301 base 6 1*10^0 + 0*6^1 + 3*6^2 = 1 + 0 + 108 = 109 in base 10 so in base 10 175 - x = 109 x = 66 in base 10 put that in base 7 7^2 = 49 17 left 2*7^1 = 14 3 left so 1^7^2 + 2*7^1 + 3*7^0 or P = 123 in base 7
December 27, 2014

physics
Note equation 1.78 seems to be missing an = sign just left of the integral sign
December 27, 2014

physics
try deleting the s on https http://books.google.com/books?id=PTj2eEbT_jQC&pg=PA67&dq=elongation+of+long+hanging+rod+due+to+own+weight&hl=en&sa=X&ei=7TGfVI_7NcufgwSx-YKYCg&ved=0CGwQ6AEwCQ#v=onepage&q=elongation%20of%20long%20hanging%20rod%20due%20to%20own%20weight&f=false
December 27, 2014

physics
Looks like a MIT 8:01 problem to me :) It is too much for me at present but this link might help a little: https://books.google.com/books?id=PTj2eEbT_jQC&pg=PA67&dq=elongation+of+long+hanging+rod+due+to+own+weight&hl=en&sa=X&ei=7TGfVI_7NcufgwSx-YKYCg&ved=0CGwQ6AEwCQ#v=onepage&...
December 27, 2014

Physics
2.3/2 = 1.15 seconds to go up 0 = Vi -4.9 t = Vi - 4.9*1.15 Vi = 5.365 m/s initial speed up the second ball must have same initial vertical component of velocity = 5.365 m/s Vi sin 60 = 5.365 so Vi = 6.51 m/s
December 27, 2014

PHYSICS
initial momentum west = 1720 v -1510(75.7) = final momentum west = (1720+1510)15.5
December 27, 2014

math
LOL ali 3/8 * 80 = 30 5/8 * 80 = 50 30/50 = 3 / 5
December 26, 2014

math
3 + 5 = 8 so 30new + 50top
December 26, 2014

math
If a student keeps asking similar questions the student needs to look at earlier replies and try to do the next one without help Jack. We can then check the answer but just telling the student how to do it time after time helps not in the least.
December 26, 2014

math
yes, ok 24/9 = 8/3 same answer
December 26, 2014

math
24/36 = 2/3 (2/3)4 = 8/3 or 2 2/3
December 26, 2014

math
(1/4)(25)sqrt 3 = 10.8 cm^2
December 26, 2014

physics
How about different colors :) ?
December 26, 2014

math
pi r^2 = s^2 4 s + 2 pi r = 3600 it seems they want you to use x for 2 pi r so r = x/(2pi) pi r^2 = x^2/(4 pi) = s^2 so 4 s + x = 360 2x/( sqrt pi) + x = 360 2.13 x = 360 x = 169.1 cm 360 - x = 4s = 190.9 cm s = 47.7 ------------------------- check r = x/(2 pi) = 26.9 pi r^2...
December 26, 2014

6th grade math
1 serving = 0.8 cups 4 cups (1 serving/.8 cups) = 5 servings or 4 * 1/ (4/5) = 20/4 = 5
December 26, 2014

science typo ?
do you mean 220 volts ? i V = 2,000 220 i = 2000 i = 2000/220
December 26, 2014

maths
if sin A = 1/2 then cos A = (sqrt 3)/2 because that is a 30, 60, 90 triangle (1/8) 3 * 3^1/2- (3/2) * 3^1/2 = -(9/8) * 3^1/2
December 26, 2014

physics
1 kg * g = (3+4) a a = g/5
December 25, 2014

binomial
if only allowed up to x^3 do it in two steps result for (x+8y)^3 * (x+8y)^2 that is easier anyway
December 25, 2014

Math
Just graph a few points working both ways from ( 0 , -2 )
December 24, 2014

Math
when x = 0, y = -2 Y increases at 45 degrees from there in both directions so it is a V with the bottom point at (0 , -2)
December 24, 2014

Algebra 2
well, we know that sqrt 4 = 2 so the answer is (1/2) sqrt 3 however in general to clear the denominator: multiply top and bottom by sqrt 4 3 sqrt 3 sqrt 4 / (3*4) = 6 sqrt 3 /12 = (1/2) sqrt 3
December 24, 2014

Physics
The 90 kg student was standing still, momentum of zero. there was a push for .0003 seconds then his speed was 5 m/s so change in momentum = 90*5 - 90*0 = 90*5
December 24, 2014

Physics
force = change in momentum / change in time 90*5/.0003 in Newtons by the way .0003 is a very short pushing time, impractical I think. (typo?)
December 24, 2014

CULCULS
exactly. I am a Naval Architect. We have a hydrostatic characteristic called "tons per inch" which is how many tons of cargo you can add to increase the draft by one inch as a function of draft. It is basically the water plane area * density of seawater :)
December 24, 2014

CULCULS
v = (1/3) pi r^2 h but r = h/2 so dr = (1/2) dh v = (1/3) pi * 2 r^3 dv/dt = (2) pi r^2 dr/dt dv/dt = pi r^2 dh/dt Note: this is just the surface area * dh/dt
December 24, 2014

Math
12/4 = 3 4,000 * 1.03^48
December 24, 2014

Algebra 1 - HEY!!!
HEY, someone named Henry already showed you how to do this sort of problem. Now start doing them yourself. Post your answers.
December 23, 2014

Algebra 1
none those two lines have the same slope of 5 so they are parallel but they do not have the same y axis intercept so they never touch each other in two dimensional space.
December 23, 2014

Algebra 1
for heavens sake put your lines in the form y = m x + b and see if they have different m, slope then if so, see if b is the same for both.
December 23, 2014

Algebra 1
same slope, same y intercept so lines on top of each other, infinite number of points
December 23, 2014

algebra
g(7) = 2*7 = 14
December 23, 2014

algerbra
call the slope m then in general for any two points on a line of form y = m x + b the slope is change in y / change in x so for two points (x1 ,y1) and (x2 , y2) m = (y2-y1)/(x2-x1) the same is true for any other point on the line (x , y) so also m = (y2 - y) / (x2 - x) or m...
December 23, 2014

Math; Please help
vary inversely t = d/v
December 23, 2014

Big History Test (Check) Part1.
The North's well-established government gave it a distinct advantage. <-- I suppose, but the main thing was the industrial base in the north and navy and railroads. I would have checked: The goal of the war changed from saving the Union to saving the Union and ...
December 23, 2014

Algebra
You are welcome.
December 23, 2014

Algebra
####### r^2 + 5 r + 1 #######_______________________ (r-5) | r^3 + 0 r^2 - 24 r - 5 ####### r^3 - 5 r^2 #######_______________________ ############# 5 r^2 - 24 r - 5 ############# 5 r^2 - 25 r ############# ________________ #################### 1 r - 5 #################### 1 r...
December 23, 2014

Algebra
well, you could guess but it only took me a minute to do long division r^2 + 5 r + 1
December 23, 2014

math
LOL this is a perfect basketball and a perfect floor so all collisions are elastic and it bounce back up to 160 ft every time? Four round trips and a fall so 9 * 160
December 23, 2014

Physics
distance = rate * time :) speed east = Ve = 1.60 * cos 20.8 speed north = Vn = 1.60 sin 20.8 time east = 22/Ve time north = 31/Vn
December 23, 2014

english
hint maybe c a........ b e
December 23, 2014

PHYSICS
Hey - You are supposed to follow what I did, not just type any old number I give you!!!!! I did r = 3.19 You can multiply by 2 to get the diameter but you better decide to understand what I did first.
December 22, 2014

algebra
Yes :)
December 22, 2014

algebra
If you go 40 miles the first hour and 40 more the second hour how far did you go? Certainly NOT 20 !!!
December 22, 2014

physics
Ac = v2/R =omega^2 r = g/.7 =9.81/.7 = 14 r = 14/omega^2 but omega = 2 pi (1/3) = 2.09 radians/s omega^2 = 4.38 r = 14/4.38 = 3.19 meters
December 22, 2014

Physics
Huh? Sin(25)*187+(36*9.81) = 432.19 the clerk is pulling UP not down -Sin(25)*187+(36*9.81) =274.1 = normal force down on floor 274.1 * .410 = 112 so 187 cos 25 - 112 = 36 a
December 22, 2014

math
.75 * .7 = .525
December 22, 2014

Earth science
Isobars help me find fronts :) The cyclone is indeed counterclockwise in the Northern hemisphere (not south of the equator where the spin around a low is clockwise to conserve angular momentum). I agree with the rest
December 22, 2014

Math and Phyics
Tension T in rope, on big mass M g - T = M a while the big mass is falling, the little mass goes up a distance h when the big mass hits ground, the little mass is moving with the speed that the big mass hits with, then coasts up until the kinetic energy of that speed is spent...
December 22, 2014

Math/Algebra 1
string = 180 + 2 (necklace) if necklace = 10 string = 180 + 20 = 200 if necklace = 11 string = 180 + 22 = 202 if necklace = 12 string = 180 + 24 = 204 etc works fine
December 22, 2014

Math/Algebra 1
string = 200 + 2 (length of necklace - 10) or string = 180 + 2 length of necklace)
December 22, 2014

redone
v = 256 pi/3 = (4/3) pi r^3 so r = 4 S = v(3/r) = 4 pi r^2 = 64 pi v = (4/3) pi r^3 = S (r/3) = (1/3) S r dv/dt = (1/3) [ S dr/dt + r dS/dt ] but S dr/dt = dv/dt = 10 30 = 10 + 4 dS/dt 20 = 4 dS/dt dS/dt = 5 cm^3/s
December 22, 2014

Calc
V = (4/3) pi r^3 so when V = 256 * pi/(3) 256 pi/(3 ) = 4 pi r^3 /(3) r^3 = 64 r = 4 d v = surface area of sphere * dr dv = 4 pi r^2 dr = 64 pi dr dv/dt = 64 pi dr/dt = 10 cm^3/s dr/dt = 10/(64 pi) so dV/dt = 4 pi r^2 dr/dt = 10 so dr/dt = 10/(4 pi ) dS/dt = 8 pi r dr/dt = 32 ...
December 22, 2014

Math and Phyics
Is there no picture?
December 22, 2014

Math and Physics - Huh ?
There are two masses M and m ? They are at two vertices of the triangle? What is at the third corner?
December 22, 2014

algebra
You are welcome :)
December 22, 2014

algebra
check -2(8) - 7 -16 - 7 -23 sure enough :)
December 22, 2014

algebra
-2 v - 7 = -23 add 7 to both sides -2 v = -23 + 7 = -16 divide both sides by -2 v = -16/-2 = +8
December 22, 2014

AP CALC
sin 3 pi/2 = sin 270 = -1 sin - 3 pi/2 = +1 change in sin x = -1 - +1 = -2 change in x = 3 pi/2+3pi/2 = 3 pi so slope from left to right = -2 / 3pi = -.2122 so where does the derivative of sin x = -.2122 ? d/dx (sin x) = cos x so cos x = -.2122 x = 102.25 degrees = 1.78 radians
December 21, 2014

Physics
if initial speed in +x direction impulse = change of momentum .0420 (-7.4 - 18.3)
December 21, 2014

ap calc
when x = 2, y = 2(4)-8+3 = +3 when x = 0, y = 2(0) -0^2 = 0 delta y/delta x = (3-0)/2 = 1.5 so where in there does f' = 1.5 ? between 0 and 1 f' = 2 - 2x so 2 - 2x = 1.5 2x = .5 x = .25 is one spot between 1 and 2 f' = 4 x - 4 so 1.5 = 4 x - 4 4 x = 5.5 x = 1.375 ...
December 21, 2014

Physics
call + x direction the initial direction of the first (3 kg) mass initial momentum = 3*2 -5*2 =6-10 = -4 final momentum also -4, mass = 8 8 * v = -4 v = -1/2
December 21, 2014

ap calc
h = e^sin x h' = cos x e^sin x cos pi/2 = 0 sin pi/2 = 1 so 0 * 1 = 0
December 21, 2014

been there done that
I just did this a little while ago
December 21, 2014

math
0.34* 10^7 + 4.7 * 10^7 = 5.04 * 10^7 but you are only using 2 significant figures so 5.0 * 10^7
December 21, 2014

math i really need help!!
5.93 * 10^5 - 0.271 * 10^5
December 21, 2014

College Math
probably sqrt (30)
December 21, 2014

physics
Now this is very similar but easier than the one you threw up from the roof of the building. You try it. I have grand kids playing hockey now.
December 21, 2014

physics
That t top in part B is the time to slow down on the way up from the top of the building to the max height. 10/9.81 seconds. THEN, it starts falling from that top point I called Htop. By the way it will pass the roof on the way down at 10 m/s down :)
December 21, 2014

physics
v = Vi - 9.81 t v = 0 at top so t = 10/9.81 at top (part B) Htop = 150 + 10 t - 4.9 t^2 (part A) now simply drops from Htop to ground Pe at top = m g Htop Ke at bottom = (1/2) m v^2 so v = sqrt (2 g Htop) (part C) we have original t rising to top now time falling v = 0 + g ...
December 21, 2014

math
6/9 = 2/3 chance of not blue on each pick if replaced, then independent 2/3 * 2/3 * 2/3 = 8/27
December 21, 2014

algebra
2 s + 5 a = 950 s+a = 250 so a = 250 - s 2 s + 5 (250-s) = 950
December 21, 2014

Physics- revolutions
Ac = v^2/r so .7 = .013 v^2/.93 solve for v we know r time = distance / speed = 2 pi r/v
December 21, 2014

phys
F = m a = 70 * acceleration = 70 * 5 * 9.81
December 21, 2014

Physics~
You are welcome :)
December 21, 2014

Physics~
sqrt (ge/gm) = sqrt 6 times period on earth
December 21, 2014

Physics
.145 * 9.81 - .4 = 1.022 N down a = F/m = 1.022/.145 = 7.05 m/s^2 down I get
December 21, 2014

Static Friction..I really Have no Idea
maximum friction force = mu m g = .2 * .4 * 9.81 = .787 Newtons so it is less than or equal to .787 Newtons (or .78 N if you use 9.8 for g and round to two significant figures)
December 21, 2014

chemistry
p V = n R T p/RT = n/V = constant here n of H2/V of H2 = n of NH3/V of NH3 V of H2 = (n of H2/ n of NH3)100 cm^3 for every 2 mols of NH3 you get 3 mols of H2 so n of H2/n of NH3 = 1.5 so V = 1.5 * 100 = 150 cm^3
December 21, 2014

Physics
T - m g = m a T = 10.0 (9.81 + 1.50)
December 21, 2014

Math
8 + 3 = 11 37 + 15 = 52 so 11:52 pm
December 21, 2014

Wolfram disagrees with me, check my algebra
http://www.wolframalpha.com/input/?i=plot+xln%28x%29%2B+%281-x%29ln%281-x%29
December 21, 2014

ap calc
y = x ln x + ln(1-x) - x ln (1-x) = ln x^x + ln [ (1-x)/(1-x)^x = ln [ x^x (1-x)^1/(1-x)^x ] = ln [ x^x (1-x)^(1-x) ] let z = 1-x dz = - dx y = ln [ x^x z^z ] = ln x^x + ln z^z = x ln x + z ln z y' = x (1/x) + ln x + z(1/z)dz/dx + ln z dz/dx = 1 + ln x -1 - ln(1-x) = 0 all...
December 21, 2014

ap calc
y = sin x y' = cos x I guess that is -3 pi/2 to + 3 pi/2 sin 3 pi/2 = -1 sin -3 pi/2 = 1 -1 - 1 = -2 -1/(3 pi) = -.1061 cos^-1 -.1061 = 96.1 degrees = 1.677 radians cos is odd function so also -1.677 radians
December 21, 2014

History
He sent General Zachary Taylor to claim an area of disputed land for the United States. http://en.wikipedia.org/wiki/South_Pass_%28Wyoming%29 The journey was surprisingly easy. the idea that it was God's plan for the nation to expand across the continent
December 21, 2014

Math-How do I do this problem?
sure change in volume = surface area * change in depth or dV = pi r^2 dh dV/dt = pi r^2 dh/dt = 12 ft^3/min so dh/dt = 6/(pi r^2) if r = 7, h = 24 or r = (7/24)h = (7/24)(10) = 70/24 so dh/dt = 6 / [ pi (70/24)^2 ]
December 21, 2014

physics
two arrows right, one left <-.------>-->
December 21, 2014

physics
yes
December 21, 2014

multiplcation
6*1000 = 6000 6*700 = 4200 6*50 = 300 6 * 0 = 0 ------------------add 10500
December 21, 2014

math
p = price of kerosene/liter 5 p/3 = price of diesel 5 p = price of petrol x = liters of diesel purchased cost of x liters of diesel = 5 x p/3 = 510 cost of x liters of kerosene = x p but x p = (3/5)(510) = 306
December 21, 2014

Calculus
6 x dx + 2 y dy = 0 dy/dx = -3 x/y at (1,2) this is-3/2 d^2y/dx^2 = -3 [ y - x dy/dx ]/y^2 at (1,2) = -3[2+3/2]/4
December 21, 2014

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