Friday
February 24, 2017

Posts by Damon

Total # Posts: 29,391

precalculus
P(k+1) = p(k) + 5
December 14, 2016

Math
volume is proportional to length cubed for similar geometry 2 times length is 4 times area 2 times length is 8 times volume so 1875(16/40)^3 = 1875(.064) = 120cm^3
December 14, 2016

physics
centripetal acceleration: To stay at the same radius, a water particle of mass m must have a force on it inward of m v^2/r. Until it hits the walls of the container, that force is missing. If the water particle happens to hit upon a hole in the wall or dribbles down the wall, ...
December 14, 2016

Science 6
B skunk eats toads I do not think toads and mice compete for who has the honor of being eaten by the fox
December 14, 2016

Algebra
1 q + 1 n = 13 1 q + .2n = 8.2 ---------------subtract .8 n = 4.8 so 6 nickels
December 14, 2016

precalculus
as you can see in the other answers, yes 4y^2+8y-2
December 14, 2016

precalculus
I guess you might mean: x = t^2-6 y = .5t - 1 ????? if so, just substitute 2y = t -2 t = 2 y +2 then x = 4(y^2+2y+1) -6 x = 4y^2 + 8y - 2 sketch that parabola
December 14, 2016

precalculus
hyperbola opening right and left center at (0,0) crosses x axis at -1 and +1 slopes at corners = +/- 2
December 13, 2016

linear programming
maximize p p = 6s+5b s+b</=70 b>/=20 s>/=10 sketch a graph there are two intersections to check (s,b) = (10,60) here p= 60+300 = 360 and (s,b) = (50 ,20) here p=300 + 100 = 400 (winner)
December 13, 2016

physics
Fup = 400 Fdown = 9.81*50 =491 so accelerating down a down = 91/50 m/s^2
December 13, 2016

Science-y Math-y Stuff
0.8 x = 4,000
December 13, 2016

Science
There was this guy in Sicily , Archimedes: http://www.math.nyu.edu/~crorres/Archimedes/Lever/LeverIntro.html http://en.wikipedia.org/wiki/Lever
December 13, 2016

Physics
alternatively you can use conservation of energy kinetic energy at bottom = potenial energy at top (1/2)mVi^2 = m g h so Vi^2 = (2 g h) h = Vi^2/2g
December 13, 2016

Physics
get vetical component of velocity up at ground, call it Vi. If shot at angle A up from horizontal then Vi = V sin A during flight acceleration = -g or 9.8 m/s^2 down or 32 ft/s^2 down speed up = v = Vi - g t = Vi -9.8 t or = Vi -32 t at top, v = 0 so t = Vi/9.8 or t = Vi/32 ...
December 13, 2016

Physics
average speed during initial slowdown = (80+40)/2 = 60km/h 60 km/h * t = 0.5 km t = 5/600 hours = (1/120)hr (1 hr/120)(60min/hr)(60s/min) = 30 seconds so a = change in speed/time = -40 km/hr /30 s = (-40 * 1000 m/3600s)/30s = -(4/3)/3.6 m/s^2 so Vi = (40/3.6) m/s final v = 0 =...
December 13, 2016

I THINK I FIGURED IT OUT!
8 works if you reverse order
December 13, 2016

Math
2/5 = 10/x x = 25
December 12, 2016

Pre-Calculus
well if you mean (x^2-1) it is D but if you really mean (lim x^2) -1 which is what you typed it is A
December 12, 2016

Algebra
9(r-2)<-73 or 9(-r+2)<-73 first one: 9 r -18 < -73 9 r < -55 r < -55/9 sure looks like a solution second one: -9 r + 18 <-73 9 r -18 > 73 9 r > 91 r >91/9 so second solution
December 12, 2016

pre-calculus
square :) side = 50/4 = 25/2 A = x y P = 2x+2y = 50 so y = (25-x) A = x(25-x) = 25 x - x^2 x^2 -25 x = -A x^2 - 25 x + (25/2)^2 = -A + 625/4 x = 25/2 sure enough so y = 25/2 and A = 625/4 = (25/2)^2
December 12, 2016

Algebra
1. 8 is a factor of 12?? 12/8 = 3/2 = 1.5 2 55/5 = 11 3. You said what P was 4 and 5 are incomplete problem statements both A and B are subsets of U 2 is the intersection of A and B
December 12, 2016

physics
suspect 1000 kg not 100 kg but anyway gravity down = 9.81 *100 = 981 N acceleration down = v^2/r Up force = F so 981 - F = ma = 100 v^2/r so F = 981 - 100 (400)/200 = 781 N but as you know if it is a real car I think 7810 N
December 12, 2016

Physics
I will guess that you mean the current leaves the battery and runs through r2 then splits and runs through r1 and r3 in parallel then joins again and runs through r4 back to the battery. If I guess right then r1 and r =3 in parallel are r1 r3 /(r1+r3) = 90*40/(130) = 3600/130...
December 12, 2016

SS HEEELLLPP!!!
I think that is a matter of opinion, not history. Check your text for what they say. I am not sure the Great Wall was such a success militarily. There seem to have been plenty of intruders from the north after. My own opinion is that the most important thing was the ability of...
December 12, 2016

Physics
x momentum = 16*30 = 480 g cm/s -x momentum = 4*50 = -200 g cm/s total x momentum = +280 g cm/s That will NOT CHANGE ! new mass = 16 + 4 = 20 g so 20 * Vx = 280 Vx = 14 cm/s
December 12, 2016

8TH GRADE MATH
60 sqrt 2 hypotenuse = sqrt (60^2+60^2) = sqrt (2 * 60^2) = 60 sqrt 2 = 84.85
December 12, 2016

physics
Vi = 30 sin 30 = 15 = initial speed UP u = 30 cos 30 = 26 = horizontal speed until caught v = Vi - 9.81 t at top v = 0 (First answer) so at top t = 15/9.81 = 1.53 seconds upward bound THE ACCELERATION IS -9.81 m/s^2 the ENTIRE TIME that it is airborne
December 12, 2016

check for typo
The way you wrote it k x^2 = (3k-5) x = +/- sqrt(3 - 5/k) but I wonder if you mean kx^2 -3kx+5 which would be x = [3k +/- sqrt(9k^2-20k) ]/2k
December 12, 2016

Chemistry
k m/r^2 so (3/4)(804)
December 12, 2016

algebra
I guess maybe you mean 6/ (?3 + 2 ) if so then [ 6/(?3+2)] * [(?3-2)/(?3-2)] 6(?3-2)/[3-4] -6?3 + 12 which is B
December 12, 2016

Physics
Archimedes said Force up = weight of fluid displaced. It displaced 6.4-5.6 = 0.8 kg of water so its volume is V = .8 kg (m^3/1000kg) = 8*10^-4 m^3 so its density is (6.4 /8)10^4 kg/m^3 =8000 kg/m^3 might be iron
December 11, 2016

physics
suspect STATIC is 0.68 .68 m g = starting Force .55 m g = constant velocity Force
December 10, 2016

Algebra
1-4k >= -11 and -1+4k >=-11 -4k >= -12 _and ___4k>=-10 4 k <= 12 __and_____k>=-2.5 k <= 3 note arrow reverse when signs changed so in the end between -3and +3 -2.5 <= k <= 3
December 10, 2016

Physics
You could have done that, patience :)
December 10, 2016

Physics
Total force up =100(9.81) = T1 sin37 + T2 sin 53 Total horizontal force = 0 = T1 cos 37 - T2 cos 53 use that to get T1 and T2 now for example moments about left end T2 sin 53 *5 = 100*9.81* X
December 10, 2016

Math
3(-2)(-2) -2(-2)(3) + 10 12 + 12 + 10 34
December 9, 2016

system of equations
Oh, and you might want to click on "very detailed solution" :)
December 9, 2016

system of equations
Click on Gauss Jordan there of course.
December 9, 2016

system of equations
5 -3 -34 10 -5 -65 (-5, +3) see http://matrix.reshish.com/gaussSolution.php
December 9, 2016

whoops sorry
xp = 100 +/- 50sqrt2 so about 30 (NOT 70 AS I SAID) if xp = 30 yp = .01x^2 = 9
December 9, 2016

Calculus
y = a x^2 100 = a(10,000) a = .01 so our parabola is y = .01 x^2 now a tangent to that parabola must pass through (100,50) slope = .02 xp at parabola y = (.02xp)x + b 50 = 2 xp + b b = 50-2xp but yp = .01 xp^2 and yp =.02xp^2 +50-2xp .01 xp^2 = .02xp^2 + 50 - 2 xp .01 xp^2 -...
December 9, 2016

where is the equation?
I might be able to solve for x given that y is 15 if I had any idea what the equation was.
December 9, 2016

la
Well I suppose your own :)
December 9, 2016

math help
3 < 4 three is less than four 4 > 3 four is greater than three and by the way 4<=4 four is either less than or equal to four
December 9, 2016

physics
31 cos 35
December 9, 2016

work and energy PHYSICS
at O where h = 0, all kinetic, E= (1/2)m Vi^2 + 0 at Q, not moving any more E =0 + m g Q Total energy during whole trip E = (1/2)m v^2 + m g h as h goes up to Q, v goes down to 0 using the start and finish points (1/2) m V^2 = m g Q Vi^2 = 2 g Q Vi = sqrt(2gQ)
December 9, 2016

Physics - studying for finals
for the second part, out in a phase angle .05 sin[(2pi/.75)(x+.375t) -PHI] (2pi/.75)(0.50) -PHI = 0 PHI = 2 pi (.5/.75)
December 8, 2016

Physics - studying for finals
A =0.0500 m L = 0.750 m T = 1/5 = 0.2 goes .75 m in .2 s so v=.75/2 = .375m/s for constant phase (x+vt) the+vt makes it left to make it go 2pi for every wavelength l or time T sin [2 pi (x+vt)/L] now the size .05 sin[(2pi/L)(x+vt)] more numbers in .05 sin[(2pi/.75)(x+.375t)]
December 8, 2016

Math
(x-1)(3x-2)(x-4i) but (x-4i)is not allowed alone, we also need its complex conjugate (x-1)(3x-2)(x-4i)(x+4i) I get 3x^4-5x^3+50x^2-80x+32
December 8, 2016

Math
8x + x = 9 x = 63 x = 7 so 8x = 7*8 which is about 56 as I remember.
December 8, 2016

physics
v = g t = 9.81 * 10 = 98.1 if no air drag but with friction terminal speed is 21 so 21 m/s
December 8, 2016

Math
x = -2 is a vertical line through the point (-2,0). Y can be anything.
December 8, 2016

Math (optimization) really confused
three fences of length x two fences of length y A = xy = 225 so x = 225/y p = total length = 2y + 3 x we want to minimize p p = 2 y +3(225/y) dp/dy = 0 at max or min dp/dy = 0 = 2 -675/y^2 2 y^2 = 675 y^2 = 337 y = 18.4 x = 225/18.4 so what is 2y+3x?
December 8, 2016

History Please Help
They were people, humans.
December 8, 2016

Physics
F * 0.24m = 31Nm so F = 31 Nm/0.24m
December 8, 2016

Physics
try throwing something up and see if time stops and moved backwards while the object falls back down.
December 8, 2016

what do you think ?
The force on this object is F = - m g so a = -g What are your answers?
December 8, 2016

Physics
v = Vi +a t 30 = 10 + 2 t t = 10 seconds but your answers are about distance d = Vi t + (1/2) a t^2 d = 10(10) + 10^2 = 200 m
December 8, 2016

Physics
You are welcome. Remember that figure skater spinning slowly with arms extended, then suddenly speeding up when she pulls her arms in :)
December 7, 2016

Physics
Ip = I of platform =(1/2)(95)(2.4^2) Angular momentum = Ip(2.3) IT STAYS THAT FOREVER New In = Ip +30*(2.4^2) In omega = Ip (2.3) omega = (Ip/In)(2.3) (Part a) b) Her I = mr^2 is zero BACK to original I and 2.3 rad/s c) (1/2) In omega^2 - (1/2)Ip(2.3^2)
December 7, 2016

physics
You are welcome.
December 7, 2016

physics
200 food calories for a half cup so 400 for a whole cup 400 cal (4184 J/cal) = 1,673,600 J watts = 1,673,600 J/600 s = 2789 Watts which is 3.74 hp
December 7, 2016

Physics
height above bottom call it h h = 33(1-cos 31) initial energy = m g h speed at bottom = sqrt(2gh) because (1/2)mv^2 = m g h for part b initial energy = m g h +(1/2)m(25) so at bottom (1/2) m v^2 = that initial energy
December 7, 2016

Physics
LOL, you answered your own question Potential energy = m g h Kinetic energy = (1/2) m v^2 so (1/2) m v^2 = m g h = 73.8*9.81*23.9 Joules (your first answer) so v = sqrt (2 g h) (by the way, remember that. You need it frequently)
December 7, 2016

Math
4 1/3 = 13/3 cans/64 oz = 13 cans/192 oz so 96 oz (13 cans/192 oz) = 6.5 cans
December 7, 2016

Math
Sketch a number line mark them on it like from left to right -13 -7 0 +1 +7
December 7, 2016

Algebra 1
3 y = - 2 x + 12 so y = (-2/3) x + 4 m = -2/3 and b = 4
December 7, 2016

History
You are welcome.
December 7, 2016

History
Oh my ! First check Constitution Amendment 10. Powers not delegated to the US gov. by the Constitution are reserved to the states or to the people (look up exact wording). Local governments do not exist in the Constitution but States reserve powers for them. We are a UNION of ...
December 7, 2016

Math
You are welcome and good luck ! I hope your grandmother comes through all right.
December 7, 2016

Math
To check #1 You say B which is y=3x+6 if x = 6 y = 3(6) + 6 = 18+6 = 24 NO! See, you can check without asking me. y = 18+b y = 8 8 = 18+b b = -10 so the RIGHT answer is y = 3x -10 which is A now slope of first = -3 second is 6y = 2x + 3 , slope = +1/3 second slope = -1/first ...
December 7, 2016

Math
9-t
December 7, 2016

Math
6*37+43 if she always works 37 hours per week income = 6 * 37 + tip otherwise income = 6 * hours + tip
December 7, 2016

Physics
second problem same Newton One stuff.
December 7, 2016

Physics
x momentum = 61.2 * 2.25 FOREVER y momentum = 66.2 * 1.30 FOREVER so final mass = 61.2+66.2 = 127.4 final x momentum : 127.4 * Vx = 61.2*2.25 Remember? final y momentum 127.4 * Vy = 66.2* 1.30 final speed = sqrt(Vx^2+Vy^2) tan theta = Vy/Vx where theta is angle above +x axis
December 7, 2016

Algebra 2 Honors
You are welcome.
December 7, 2016

oh my
My work - 2 = 1/4 ?(100 - h) I multiplied both sides by 4 from - 8 = ?(100 - h) ------------- OK SO FAR BUT square both sides 64 = 100 - h h = 100-64 h = 36 domain from 100-h must be + 0<h<100 for range if h = 0, t = 10/4 hits ground if h = 100, t = 0 drop it then so 0&...
December 7, 2016

Thank you Philip
Thanks :)
December 7, 2016

Physics
3.4 WHAT?? I assume radians/second but hard to say. I will use that but if RPS or something, convert I disk = (1/2)m r^2 so Id = .5*.4*.36^2 and It = .5 * 1.7 * .36^2 initial angular momentum = It*3.4 final angular momentum (the same of course) = It omega +Id omega = omega(It+...
December 7, 2016

Math
13 people ( 2 pounds/5 people) = 26/5 = 5.2 pounds
December 7, 2016

Chem
http://www.google.com/search?q=positron+decay&ie=utf-8&oe=utf-8
December 7, 2016

math
You already have the answer minimum cost is at the vertex x = 20 cars and C = 700 dollars this is a parabola, its vertex is at the bottom,
December 7, 2016

Math
constant slope, straight line y = m x + b m is constant rate of change of y with x
December 7, 2016

math algebra
3.2 = .01 h^2 + .2 h + 1.2 .01 h^2 + .2 h - 2 = 0 h^2 + 20 h - 200 = 0 h = -10+/- 10sqrt3 h = 7.32 hr ===================== check h = about 7.3 .01 h^2 = .53 .2 h = .15 + 1.2 = 3.2 ok, it works
December 7, 2016

Statistics
Combinations p = .65 1-p = .35 P(7,10) = C(7,10) .65^7 * .35^3 C(7,10) = 10!/[7!*3!] =10*9*8/[3*2] = 5*3*8 = 120 so 120 * .65^7 * .35^3 = .252
December 7, 2016

Physics
there are 3600 seconds in an hour 2000 hr (3600 s/hr) = 7,200,000 seconds
December 7, 2016

math
You are welcome.
December 7, 2016

math
where is the vertex of that parabola? You do not say if you know calculus so I will assume we do it the hard way with algebra .009 x^2 -1.08 x = -h -.4 x^2 - 120 x = -111h - 44.4 x^2 -120 x + 3600 = -111h + 3556 (x-36)^2 = -111(h-32) vertex at x = 36 and h = 32 32 -26.5 = 5.5
December 7, 2016

Physics
friction force = 10*9.81*.42 = 41.2N net force = 200 - 41.2 = 158.8 N a = 158.8 / 10 = 15.9 m/s^2
December 7, 2016

produces?
if you put 150 in and get 40 out it is 100(4/15) = 27% but it has to get energy from somewhere. It can not "produce" 150 + 40 +110 without putting any energy in. I suspect a typo in the problem description. It does not produce 150 J, it absorbs 150 J
December 7, 2016

physics
sin 24 = h/3 v = sqrt (2 g h) Now this is virtually the same as your roller coaster problem. Study conservation of energy and potential energy in gravity field.(mgh) and kinetic energy (.5 m v^2)
December 7, 2016

Chemistry
perhaps this can help: http://physics.stackexchange.com/questions/7993/photon-hitting-an-atom-with-higher-energy-than-needed-to-ionize Also maybe Google: Einstein photoelectric effect
December 7, 2016

Physics
check, drops 15 meters to top of loop v^2 = 2 g (15) needs v^2/30 = g sure enough 2*15 g /30 = g
December 7, 2016

Physics
Note this does no depend on the mass (lucky or it would be different for skinny kids and fat adults), or even on g (independent of planet:)
December 7, 2016

Physics
g = v^2/r at top of loop g = v^2/30 solve for v^2 = 30 *g now the car drops A-2r to that point at the top of the loop (1/2) m v^2 = m g (A-60) v^2 = 2 g(A-60) 30 g = 2g (A-60 ) = 2 g A -120 g 150 g = 2gA A = 75 check my arithmetic !
December 7, 2016

Trignometry
He told you how to do it 1. add the south components of each to get the south component of the resultant , S 2. add the west components of each to get the west component of resultant, W get the magnitude sqrt(S^2+W^2) tan A =W/S where A is angle west of south
December 7, 2016

wrong
(4*4)/(4*6) = 4/6 = 2/3
December 7, 2016

Math
x _y____y(n)-y(n-1) ___ next diff 1__0______ 2__5______ 5 3__10_____ 5____________0 4__15_____ 5____________0 5__20_____ 5____________0 6__25______5____________0 THAT is constant diff now x _y____y(n)-y(n-1) ___ next diff 1__1______ 2__4______ 3 3__9_______5____________ 2 ...
December 7, 2016

Physics
1 what? coulombs/m^2? coulombs/cm^2 ? I will assume m^2 and call it x area = A = 4 pi r^2 A = 4 pi (r)^2 Q = 1* A potential= V = k Q/r = Q/(4 pi eo r) V = 1* 4 pi r^2/(4 pi eo r) V = r/eo
December 7, 2016

Physics
mass(specific heat * 40 + heat of fusion of water)
December 7, 2016

  1. Pages:
  2. <<Prev
  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. 16
  18. Next>>