Saturday
February 6, 2016

Posts by Damon

Total # Posts: 25,133

parentheses ?????
What is the numerator and what is the denominator? If something is squared write x^2 cubed write x^3 (2x^4 + 7) maybe ????
December 28, 2015

Math
6/100 = 3/50 175/1000 = 35/200 = 7/40
December 28, 2015

math
.3 /(1/7) = 2.1 per mile 2.1 * 26
December 28, 2015

Algebra 1
(y-2) / (x-5) = 3 y-2 = 3(x-5) the last one
December 28, 2015

typo ? Linear programming problem
What does this constraint mean? limited by the formula x+2y,+1,400. I have to leave, hope Steve sees this.
December 27, 2015

More typos
Seems to be a bad typing day hs moment of intial 30kg Suspect you mean moment of inertia but the units are wrong. If it is I = 30 kg m^2 then torque = I alpha alpha = angular acceleration = 40 * 0.20 N m / 30 kg m^2 omega = alpha * t theta = (1/2) alpha t^2 number of revs = ...
December 27, 2015

science
depends how smooth and how high you push If it is perfectly smooth so the sphere spins freely without any friction force causing it to roll along the table, then that force F is the only net horizontal force on the sphere and a = F/m
December 27, 2015

Math
2(sinx/(1+cosx))d/dx (sinx/(1+cosx)) let y = sinx/(1+cosx) dy/dx=[(1+cos)cos + sin cos ]/(1+cos)^2 = cos[ 1+cos + sin]/ (1+cos)^2 so put that back in 2(sin/(1+cos))*cos[1+cos+sin]/ (1+cos)^2 2 sin cos(1+cos+sin)/(1+cos)^3 I do not see any simplification either.
December 27, 2015

math
f' = 2 x /(x^2+1) f" = [ 2(x^2+1)- 2x(2x) ]/(x^2+1)^2 = [ 2x^2+2 -4 x^2 ]/(x^2+1)^2 2[1-x^2] /(x^2+1)^2
December 27, 2015

whoops trick question
Vi = 17 sin 20 = 5.81 t = 5.81/9.81 =.593 seconds upward so in the air 2*.593 = 1.19 seconds in the air so it is not in the air for five seconds and the answer to part a is d = u t = 17 * cos 20 * 1.19 = 19 meters
December 26, 2015

physics
I guess you mean 20 degrees above horizontal. u = horizontal velocity, does not change = 17 cos 20 so a) (17 cos 20)4 b) u = 17 cos 20 At the highest point, there is no vertical velocity, so the answer is u = 17 cos 20
December 26, 2015

Precalc
The i and j are unit vectors in the x any y directions. This vector is of magnitude 2.83 and its direction is 45 degrees counterclockwise from the x axis so its components are X direction: 2.83 * cos 45 Y direction: 2/83 * sin 45 so: i * (2.83*cos45) + j*(2.83*sin45)
December 26, 2015

Mathematics
draw altitude from center of circle to center of chord. length 12 half of chord length 5 5, 12, 13 right triangle results r = 13
December 26, 2015

dr.khastagir govt girls high school
let c = tan A d = sin A P = c + d so p^2 = c^2 + 2 c d + d^2 q = c - d so q^2 = c^2 - 2 c d + d^2 p^2+q^2 = 2 (c^2 + d^2) = 2 (tan^2 A + sin^2 A) so what is the question?
December 26, 2015

basic allied math
deci
December 25, 2015

English
1. is ok 2. is not A study is a discrete thing. If there were several studies you would say "according to studies". However you would not say "a research" because research is an action. It should be; "According to research"... or according to ...
December 24, 2015

Chemistry
I think you will get Zinc Oxide which you put on your nose to prevent sunburn. White gooey stuff. At the same time you will increase the temperature of earth by releasing carbon dioxide into the atmosphere. This has little effect on the incoming ultraviolet that burns your ...
December 24, 2015

Stats
http://davidmlane.com/hyperstat/z_table.html
December 24, 2015

Physics
You are welcome. Check my algebra of course.
December 23, 2015

Physics
http://www.jiskha.com/display.cgi?id=1450909117
December 23, 2015

Physics
That sure looks familiar
December 23, 2015

physics 1
height of cliff = h height of top of second experiment = h + 2 Experiment 1: h = (1/2) g t^2 = (1/2) g (4.15)^2 h = g (8.61 ) so g = h/8.61 Experiment 2 rise part: initial speed up = Vi v = Vi - g t v = 0 in 2 meter rise 0 = Vi - g trise so trise = Vi/g 2 = Vi trise - (1/2) g...
December 23, 2015

Math
well what are the choices for tens digit 1 ---> 3 2 ---> 6 3 ---> 9 and bigger will not work so 13 26 39
December 23, 2015

physics
cyclist 1 1 hour out 20/15 = 4/3 hour back total time = 7/3 hour so the second wants to go out for (1/2)(7/3) hours = 7/6 hour at 10 km/hr 70/6 = 11 2/3 kilometer
December 23, 2015

algebra
multiply first equation by 5 and the second equation by 3 20 x + 15 y = 60 21 x + 15 y = 78 ------------------subtract -1 x = - 18 so x = 18 now go back and find y
December 23, 2015

Physics
http://www.jiskha.com/display.cgi?id=1450906690
December 23, 2015

History
Hey, they have to blame it on the natives and make themselves feel justified.
December 23, 2015

Mathematics
well try 11 of course you could do 14/ 8 which gives 22 or 28/16 etc etc but they asked for the LEAST
December 23, 2015

Math
- 1/sin^2 --------------- (1 + cos/sin)^2 -1 ------------------------------ sin^2 [ (1+cos/sin)(1+cos/sin)] -1 -------------------------- (sin+cos)(sin+cos)
December 23, 2015

no copy and paste
You probably tried to paste the figure but that does not work here.
December 23, 2015

science help
The one with the lowest frequency has the lowest energy per photon. That means C here I suppose although I have no idea what D is. A fish?
December 22, 2015

science help PLS
Transverse is like a guitar string Longitudinal is what we are talking about with sound. Both types propagate.
December 22, 2015

whoops
Oh sorry, missed the - sign -14 +16 = 4 D
December 22, 2015

Algebra
huh? 14 + 8 * 2 = 14+16 = 30
December 22, 2015

English
I could get to the bus stop where I had to get off. My school is near the bus stop. I narrowly entered the school gate. Many students were running into the school gate not to be late. ============================ Maybe: The bus reached the bus stop near my school where I get ...
December 22, 2015

physics
first do the sidewalls that is a uniform disk of radius Rout minus a uniform disk of radius Rin (You did not give me the outside radius of tire and inside radius of tire) Then you have the easy part, the thread which is simply m Rout^2 of course to do m you need to do the ...
December 22, 2015

Algebra 2 (Math)
I agree
December 22, 2015

Dr.tsegay
a + 2 d = (3/4)[ a + 5d ] and 2 a + 7 d = 60 ------------------------ (1/4 a -7/4 d = 0 or 1 a - 7 d = 0 2 a + 7 d = 60 ------------------- add 3 a = 60 a = 20 d = 20/7 an = 20 + (n-1)(20/7)
December 22, 2015

Chemistry
half life of carbon 14 is about 5730 years .125 = (1/2)^n where n is the number of half lives log .125 = n log .5 n = 3 half lives 3 * 5730 = 17,190 years old
December 22, 2015

metreology
This question is so important to us that I am going to answer it just to make sure you know. Radiation comes in from the sun in a wide spectrum but maximum ultraviolet although as you know there is lots of visible. That energy mostly gets used to power things like plants and ...
December 22, 2015

Math
Not enough information c^2 = a^2 + b^2 P = a + b + c = 40 or P = a + b + sqrt(a^2+b^2) = 40 now if it is isoceles, a = b, then P = 2 a + sqrt (2 a^2) = 3.414 a = 40 A = (1/2) a b = (1/2)a^2 = (1/2)(40/3.414)^2 = 68.6
December 22, 2015

physics
1. Well, first of all The average VELOCITY is ZERO because it went nowhere. The arrow from the starting point to the end point has no length, no displacement. the average speed however id the total distance 8 km / 22 min 2. 83 km/hr(1 hr/3600 s)(1000 m/km)= 23 m/s v = Vi + a t...
December 22, 2015

math
10.5 km/cm which is 1,050,000/1
December 22, 2015

math
385 ( 1 in/25 mi) = 15.4 in
December 22, 2015

Huh?
How would I know? I have no idea what a or d is.
December 22, 2015

math
I have no ideas because I do not know the shape or the scale
December 22, 2015

math
6 ft (9.6/12) = 4.8 ft
December 22, 2015

science
CaO + 2HNO3 ---> H2O + Ca(NO3)2 ?? CaO = 40 + 16 = 56 grams/mol so we have 1.5/56 = .0268 mols of CaO
December 22, 2015

science help
You need a good storage system so you can provide energy left over from the windy days on the calm days. (super batteries, pump up to a reservoir, flywheels, whatever.
December 21, 2015

science help
Yes of course. The others are nutty.
December 21, 2015

science help
I have no idea what your experiment was.
December 21, 2015

science help
yes
December 21, 2015

science help
Oh come on, If you squeeze it together it gets denser If you release the pressure it expands and gets less dense
December 21, 2015

math help pls pls
3x + 2 y = 27 2 x + y = 27-11 = 16 ================= The student's conclusion is correct because the solution to the system of equations 3x + 2y = 27 and 2x + y = 16 is (5, 6). C
December 21, 2015

math help pls pls
Now I did the other one. You do this one.
December 21, 2015

pharmacy tech
.01 x + .05(30 - x) = .03 (30)
December 21, 2015

world civilizations II
I vote for a) ( Poland , Russia)
December 21, 2015

math help pls pls
by the way, now that we know, we go back and see why They will have the same solution because the first equation of System B is obtained by adding the first equation of System A to 4 times the second equation of System A.
December 21, 2015

math help pls pls
GRAPH THEM ALL !!! I tend to put them in the slope intercept form y = m x + b to graph them System A first 6x + y = 2 or y = - 6 x + 2 second −x − y = −3 or y = -1 x + 3 now I can easily graph them where do they cross? -6x+2 = -1 x + 3 5 x =-1 x = -1/5 so ...
December 21, 2015

Physics
i = V/R = 6/3 = 2 amps in parallel, currents add in series, voltages add
December 21, 2015

MATH HELP
whew, you had me worried there.
December 21, 2015

MATH HELP
I guess you will have to check your text book :)
December 21, 2015

MATH HELP
y = x/2 -3 and y = x/2 -5 two parallel lines with the same slope but different y axis intercepts therefore they never, ever, cross and there is no solution
December 21, 2015

Math
http://davidmlane.com/normal.html
December 21, 2015

History [Check?]
Stalin? Free elections ????
December 21, 2015

our own English school
That certainly would be a good start :)
December 21, 2015

Algebra
more than -5 and less than +5 -5 < x < +5 line between x = -5 and +5 less than -5 or more than +5 -5 > x > +5 line left of -5, skip -5 to + 5 and line right of +5
December 21, 2015

Algebra
0 </= x < 8
December 21, 2015

physics
The 2 kg hanging block: x defined down m a = m g - T T = m (g-a) T = 2 (9.81-a) The 3 kg bock on the slope: now x is up the slope T - m g sin 30 = m a T = m (g/2+a) T = 3 (4.9-a) your turn.
December 21, 2015

khalsa model senior secondary school
http://www.jiskha.com/display.cgi?id=1450703655#1450703655.1450708788
December 21, 2015

physics
Check the questions and answers below for hints. For example: http://www.jiskha.com/display.cgi?id=1328161975
December 21, 2015

Physics
Agree if the battery is dead BUT If the circuit is open the voltage is whatever the battery was charged to. If the circuit is "shot circuited", the terminals connected by a thick wire of zero resistance, the current becomes infinite and the voltage zero V = i R V = i...
December 21, 2015

Physics projectile motion
Click on some of the earlier problems below, for example: http://www.jiskha.com/display.cgi?id=1383313306
December 20, 2015

physics
g is -9.8 if up is positive The only time I did not use - is when the thing was falling. I knew I had - on both sides. I could have written - (h +19.6) = - 4.9 t^2 because it goes DOWN that distance with a negative acceleration starting at the tip top of its path.
December 20, 2015

physics
v = Vi - 9.81 t v = 0 at top so 0 = Vi - 9.81*2 Vi = 19.6 m/s up h = Vi t - 4.9 t^2 = 19.6(2) - 4.9(4) = 19.6 meters above roof then falls for 8 - 2 = 6 seconds from way up there h+19.6 = 4.9 (36) h = 157 meters, 50 stories high !
December 20, 2015

physics
40000/3600 = 11.11 m/s 15 m/11.11 m/s = 1.35 seconds to get to Porsche starting point time t from porsche start. Vp = 3 t xp from light = (1/2)3 t^2 t car = (t - 1.35) seconds xc from light = 11.11 (t-1.35) when does xp = xc ? 1.5 t^2 = 11.11 (t-1.35) 1.5 t^2 - 11.11 t + 15 = ...
December 20, 2015

Physics poweful diver
By the way 20 meters per second is quite a spring. Are you sure it is not 2 ? say you jump with a speed up of 20 m/s from the ground at top. I will call g = 10 instead of 9.81 0 = 20 - 10 t t = 2 seconds upward h = 5 t^2 = 5(4) = 20 meters that is like 20 yards 60 feet !!! ...
December 20, 2015

Physics
v = Vi - 9.81 t h = Hi + Vi t - 4.9 t^2 A. after .5 seconds: v = 20 - 9.81(.5) h = 5 + 20 (.5) - 4.9 (.25) B. 0 = 5 + 20 t - 4.9 t^2 solve quadratic equation for t when h is zero C. at top v = 0 0 = 20 - 4.9 t at top use t at top for height h = 5 + 20 t - 4.9 t^2 D. v = 20 - 8...
December 20, 2015

PHYSIS
omega = sqrt (k/m) so 2 pi f = sqrt (k/m) so 2 pi/T = sqrt (k/m) so 2 pi/ 6.60 = sqrt (k/53) solve for k then m g = k x x = 53*9.81/k
December 20, 2015

Math mystery
if it is equilateral why does it have three different side lengths?
December 20, 2015

math
a + a+d + a+2d = 3 a + 3 d = 3(a+d)=12+3d firat = 4 third = 4+2d 7th = 4+6d r and the geometric is b, br, br^2, br^3 ... 4 = b 4+2d = b r = 4r 4+6d = b r^2 = 4 r^2 so 2 d = 4 r - 4 or d = 2r-2 6 d = 4 r^2 -4 or d = (2/3)r^2 -2/3 2 r - 2 = (1/3) (r^2 - 1) 6 r - 6 = r^2 - 1 r^2...
December 20, 2015

maths
10 m (100 cm/m) = 1000 cm
December 20, 2015

physics
p = m v so v = p/m Ke = (1/2) mv^2 = (1/2) m (p^2/m^2) = (1/2) p^2/m
December 20, 2015

physics massive and momentous homework dump
Have you tried to do all these problems or do you just think I need the practice? momentum after = momentum before momentum is a vector so momentum in the x direction after = momentum in the x direction before and momentum in the y direction after = momentum in the y direction...
December 20, 2015

math
(5 miles/ 2 minutes )60 minutes = 150 miles I assume on a race track :)
December 19, 2015

Math
a y = -x + b y = -x/a + b/a
December 19, 2015

math
h = 9 - .5 t or if you insist on x and y y = 9 - .5 x (0,9) obviously (1,8.5) (2,8) (3,7.5) etc etc etc yes, there is one y for every x y = 9 - .45 x
December 19, 2015

science help PLS
Hey, I you squeeze it, it gets denser !
December 19, 2015

science help PLS
yes
December 19, 2015

science help PLS
well, I do not think you need anything but imagination here but anyway if PV = n R T density proportional to n/V n/V = P/RT if T constant density goes down if pressure goes down
December 19, 2015

MATH HELP
F(t) = 6 t ? t is time or year F(6) = 6 * 6 = 36 Could you have a typo? Do you mean something else by 3(2) maybe 3^2 which is 9 but that would give 54 which is not a choice.
December 19, 2015

math
Surely the question was not worded that way. Do you mean assessed value of property? (8/12)(12300)(.16) = 1312 By the way a 16% tax rate is much, much higher than any I have ever heard of. No one would buy property there.
December 19, 2015

Math
II think you mean t^2 + 4 t + 30 v = 2 t + 4 a = 2 I do not know why you are supposed to know that if you are not taking calculus.
December 19, 2015

Math
Yes, that is the only one where he makes 200 or more
December 19, 2015

math
cups a cups is 8 ounces of water a pint is 16 ounces of water 8 cups is 4 pints a pint is a pound the world around (500 cm^3 of water (500 grams) is often called a pound :)
December 19, 2015

Physics (Heat)
Dry air moving over your skin causes evaporation from the surface which is cooling as well as brute force warming up if your skin is warmer than the moving air.
December 19, 2015

Math
2w+2L = 46 so w+L = 23 L = w+5 so w + w + 5 = 23 2 w = 18 w = 9 then L = 14
December 19, 2015

Mathematics
ab = 10 a + b a + b = 4 so b = (4-a) 10 b + a - 10 a - b = 18 - 9 a + 9 b = 18 -9 a + 9 (4-a) = 18 -18 a = -18 so a = 1 then b = 3 and the number is 13
December 19, 2015

Physics for
If you mean the spring force is F(x) = - k x^4 the force you have to exert is the negative of that then integral from x1 to x2 of integral-F(x) dx which is (1/5)k [ x2^5 - x1^5 ] = (1/5) k [ 1.35^5 - .73^5 ]
December 19, 2015

math
I do not know what specific level you are talking about. around third grade "Singapore Math" texts seem to be common, for example "Math in Focus" , The Singapore Approach, which you can find online for example: http://www.rainbowresource.com/prodlist.php?...
December 19, 2015

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