Wednesday
July 27, 2016

Posts by Damon

Total # Posts: 26,563

physics
fell distance 4.05 so lost potential energy m g h = 3 * 9.81 * 4.05 That is kinetic energy of bucket plus spool v = omega R = .6 omega call omega = w Ke = (1/2) m v^2 + (1/2)I w^2 = (1/2)v^2 (m + I/.36) I = 5 * .5 * .36 = so I/.36 = 2.5 so 3 * 9.81 * 4.05 = .5 * v^2 *(5.5) ...
April 6, 2016

Physics miscounted
134.4
April 6, 2016

Physics
C = Q/v = 40*10^-6 Q = 40 * 10^-6 v i = dQ/dt = 40*10^-6 dv/dt let v = V sin wt dV/dt = V w cos wt so i = 40*10^-6 V w cos w t max i = 40*10^-6 V w w = 2 pi f = 2 pi(60) = 377 so max i = 40*10^-6 * 377 V so V = (2.26/(15080)) 10^6 =1344
April 6, 2016

Math help please
YOU MEAN sin^2 x=[ 1-cos(2x) ] /2 or 2 sin^2 x = 1 - cos(2x) cos 2 x = cos^2 x - sin^2 x so 2 sin^2 x = 1 - cos^2 x + sin^2 x sin^2 x = 1 - cos^2 x or sin^2 x + cos^2 x = 1 which is true
April 5, 2016

Physics
620 * .39 = x * 1.53 so (.39/1.53)620
April 4, 2016

Algebra
maybe you want: 3 7 2 3,7 3,2 7,2
April 4, 2016

English
Either but I would pick 2 because in the end the person, not the food, is supposed to be healthy.
April 4, 2016

Math
log3 (3m) log a + log b = log ab That is how a slide rule works. That is how old I am :)
April 4, 2016

PHYSICS!!!
ke at bottom = (1/2) m v^2 = (1/2) m (144) = 72 m Joules pe at top = m g h= m (9.81)(12.2 sin 18 = 37 m Joules so Lost 72-37 = 35 m Joules to friction Friction force = mu m g cos 18= 9.33 mu m work done by friction = 9.33 mu m * 12.2 = 114 mu m so 35 m = 114 mu m mu = 35/114...
April 4, 2016

PHYSICS!!!!
10 km/hr = 10/3.6 = 2.78 m/s 3 km/hr = 3/3.6 = .833 m/s 5 km at 10 km/hr --> 30 min which is 30 *60 = 1800 s energy = 700*1800 = 1.26*10^6 Joules 5 km at 3 km/hr --> 6,000 s 6,000 s * 300 w = 1.8*10^6 Joules ==============================
April 4, 2016

Physics
assuming that your potential energy is defined as zero at the bottom of the hill, all your energy is kinetic by the time you get there. 800 + 200 = 1000 Pert of this problem statement is missing though. In potentials, all you can define is differences. You have to define some ...
April 4, 2016

Math
2 pi r = 2 pi *7 = 14 pi inches
April 4, 2016

PHYSICS!!
change in potential energy = m g h = 2219*4*sin 30 = 4438 Joules = (1/2)mv^2 + (1/2)I w^2 but w = v/r = v/.4 = 2.5 v so 4438 = (1/2)(226)v^2 + (1/2)(22.6)(6.25 v^2) or 4438 = 184 v^2 so v = 24.2 m/s and w = 60.4 radians/s Torque * angle = change in Ke T * 2 pi = (1/2) I w^2
April 4, 2016

PHYSICS!!
first mass of rubber = 2000 * .3 * ∫ 2 pi r dr from r = .2 to r = .4 = 600 (2 pi) (1/2)(.16-.04) = 226 kg 226 * 9.81 = 2219 Newtons weight I = 2000*.3 *∫ 2 pi r^3 dr = 3770 (1/4)(.4^4-.2^4) = 22.6 ===================
April 4, 2016

PHYSICS!!
time = 100 * 3600 = 3.6 * 10^5 s so energy used= 120*3.6*10^5 = 432 * 10^5 Joules = m g h = 65 * 9.81 * h so h = .677 * 10^5 = 67,700 meters
April 4, 2016

Math
but 24 inches = 2 feet so r = 1 foot (4/3) pi (1)^3 = 4.19 ft^3 by the way 4/3 x 3.14/1 = 1.395 is wrong --- should be 4.19
April 4, 2016

Math
3/4 = .75 3/8 = .375 which is bigger?
April 4, 2016

Math
2(3.14 x 0.25) + 2(3.14)(.5)(4) answer in feet^2
April 4, 2016

no
You have to use all feet or all inches r = 0.5 feet NOT 6 inches
April 4, 2016

math
s + (s+30) = 36 2 s = 6 s = 3 f = 33
April 4, 2016

Math-soh cab toa
sin 30 = h/70 but we all know sin 30 = 1/2 so 35
April 4, 2016

Physics
final angular momentum about axis of rotation = initial angular momentum initial ang mom = 78*1.6 * 2 = 250 kg m^2/s final ang mom = 78 (2)^2 omega + 651 omega omega ( 963) = 250 omega = .26 radians/second
April 4, 2016

History
I would have chosen B A ---- interchangeable parts, came before assembly lines for example in weapons manufacture (Colt in Connecticut for example)
April 4, 2016

History
I suppose I have to agree, but we lost our forests here in Massachusetts to farming and wood stoves long before we had woolen mills and Springfield rifles. The really tall pines of course were marked with broad arrow symbols and reserved for the king's masts.
April 4, 2016

Hard math question
suspect 1 * 2 * 4 = 8
April 4, 2016

Engineering science
oh and for time avergae speed = 6/2 = 3 m/s so t = 4/3 seconds
April 4, 2016

Engineering science
normal force = m g cos 25 friction force = mu m g cos 25 = force down slope = m g sin 25 so sin 25/cos 25 = tan 25 = mu = .466 =================== at 10 degrees friction force = .466 m g cos 10 = .459 m g work done by friction = .459 m g d = loss of kinetic energy = (1/2)m(36...
April 4, 2016

Math
anything with straight sides and pointy top has volume = (1/3) height * base area so 1/3
April 3, 2016

trigonomentry help!!!
(x-q)(x-4q) = a x^2 + b x + c x^2 - 5qx + 4 q^2 =a x^2 + bx + c if a = 1 b = -5 q c = 4 q^2 then 4 b^2 = 100 q^2 and 25 a c = 100 q^2 and 100 q^2 -100 q^2 = 0 all right
April 3, 2016

chem
Mg + 2 HNO3 → Mg(NO3)2 + H2
April 3, 2016

Math
Perhaps you meant 0.15 % ?????
April 3, 2016

Math
55 = .15 x x = 366 2/3 which is about 367 :)
April 3, 2016

Geometry
rectangle is (53 + 6) by (55 + 6) or 59 by 61 2*59 + 2*61
April 2, 2016

algebra
I gues you are looking for a straight line of slope m = 3 through the point (4,5) y = 3 x + b 5 = 3*4 + b 5 = 12 + b b = -7 so y = 3 x - 7
April 2, 2016

computer science
I guess I would let n = 0 and y = 0 then I would say n = n+1 y = 12 * n if y > 30 go to the end immediately and stop then I would store and print y go back to that n = n+1 stop and end
April 2, 2016

Math
e^cos t = value at t - value at pi = value at t - e^cos pi but cos pi = -1 so e^cos t = value at t -e^-1 or e^cos t = value at t - 1/e so value at t = 1/e + e^cos t ------------------- now do value at t - value at 0 value at 0 = 1/e + e^1 = 1/e + e value at t = 1/e + e^cos t ...
April 1, 2016

science
work done = increase in kinetic energy = (1/2) m (V2^2-V1^2) V2 = 72/3.6 meters/second V1 = 54/3.6 meters/second m = 1500 kg then answer will be in Joules
March 31, 2016

physics
distance from each = d = sqrt(5^2+12^2) = 13 cm = .13 meter however we may notice that the component along the bisector will be zero due to the opposite signs of the charges. However that is no true of the component along the direction between charges E = k q/.13^2 for each ...
March 31, 2016

Science
http://en.wikipedia.org/wiki/Electromagnet
March 31, 2016

Science
the B field strength is proportional to the number of turns.
March 31, 2016

Mathematics
Looks like a typo problem to me the original was probably round to the nearest thousand dollars, 2000
March 31, 2016

math
Well done :)
March 31, 2016

math
Good :)
March 31, 2016

math
You are welcome, but more importantly do you know how to tell a straight line from a parabola or an exponential now?
March 31, 2016

math
You typed y = 5x, look up above. I found it correct in one of your earlier postings.
March 31, 2016

AHHH!! NO
Look, they are asking you which of these is a straight line with constant slope. In other words which looks like Y = m X + b That is B y = 19 x - 10 A, x^2 - 5 x - 14 is a QUADRATIC, parabola C, y = 5^x (NOT y = 5 x ) is exponential D, y = .03 x^2 etc is QUADRQATIC, parabola
March 31, 2016

ah ha - you typed it wrong
B)y = 19x – 10 C)y = 5^x NOT THIS. This is NOT 5 x as you wrote later.
March 31, 2016

math
There are two with constant slopes. B and C If you think there is only one answer, you have a typo.
March 31, 2016

math
B and C 19 and 5
March 31, 2016

College Algebra
the slope is -29 crimes per year In other words the number of crimes decreases by 29 every year. when t = 0, C = 31,000. That is the number of crimes when the equation started in 1998 I suspect the 31,000 is a typo as is the 29
March 31, 2016

math
the derivative is constant in B and C
March 31, 2016

Physics
334 * 2000 = 668,000 J
March 31, 2016

Geometry
x^2 + 10 x - 1200 = 0 (x-30)(x+40) = 0 x = 30 or x = -40
March 31, 2016

Algebra 2
3 150 4 150 + d 5 150 + 2 d = 180 so d = 30/2 = 15 month 1 = 150-30 = 120 An = 120 + (n-1)15 A12 = 120 + 11(15) = 285 yes correct 500 = 120 + (n-1)15 n - 1 = 25.33 n = 26.33 yes, 27
March 31, 2016

math
I guess A is at center and AB bisects CD ???? we need to know angle at center cos (T/2) = 4/5 T/2 = 36.9 degrees T = 73.7 degrees so area = (73.7/360) pi R^2
March 31, 2016

physics
horizontal speed = u = 50 cos 37 t = 80/u then how high is it at t h = (50 sin 37) t - 4.9 t^2 then d = sqrt (80^2 + h^2)
March 31, 2016

math
http://davidmlane.com/hyperstat/z_table.html
March 31, 2016

math
http://davidmlane.com/hyperstat/z_table.html
March 31, 2016

Algebra 2
d = -27 + 22 = -5 -7 - 5 = -12 -12 - 5 = -17 -17 - 5 = -22 so the last one on the list
March 31, 2016

Math - Slope intercept
sure looks like it to me. They asked the same question twice. I bet they meant to say: Write the equation in standard form 6 x - 3 y = 2 then solve for y in slope intercept form but who knows
March 31, 2016

luthayi high school. science
http://www.nlm.nih.gov/medlineplus/ency/article/002680.htm
March 30, 2016

This is a trick question
Velovicy is a VECTOR north one way, south back 31 lengths, 30 of which were back and forth so went 50 meters total north in the end How long did it take? 31 * 50 = 1550 meters back and forth at 900 m/3600 s time = 1550 *3600/900 = 6200 seconds so 50 meters/6200 seconds = 0....
March 30, 2016

physics
I will do position last a = dv/dt so a = -10*10^7 t + 3*10^5 zero at t = 3/10 * 10^-2 = .003 seconds a is positive for the whole .003s find v at t = .003 for part c x = integral v dt with x = 0 at t = 0 so x = (1/3)(-5.00×10^7)t^3 +(1/2)(3.00×10^5)t^2 length of ...
March 30, 2016

physic
k = 20 N/.098 m = 204 N/m m = 20/9.81 = 2.04 kg omega = w = sqrt (k/m) radians/second so w = sqrt (204/2.04) = 10 rad/s if x is distance from equilibrium position, positive up x = -.05 cos 10 t
March 30, 2016

but
You may not care about order withing each committee so perhaps you mean combinations, not permutations C(8,5) = 8! /[ 5! (8-5)! ] = 8*7*6/[3*2] = 56
March 29, 2016

Geometry
w L = 500 L = 5 w/4 w(5w/4) = 500 w^2 = 400 w = 20 L = (5/4)20 = 25
March 28, 2016

Physics 110
well what is the specific heat or heat capacity of water in Joules or Calories (whichever your class is using)per gram (or kilogram or oz or pound) degree centigrade (or Fahrenheit) anyway call it C Heat in = C * 500 (40-10)
March 28, 2016

finance
EUR = (1.1210/1.125 ) USD but USD = (112.15/114.25 ) JPY so EUR = (1.1210/1.125)(112.15/114.25 ) JPY so EUR/JPY =(1.1210/1.125)(112.15/114.25 )
March 28, 2016

Statistics
https://www.khanacademy.org/math/probability/statistics-inferential/normal_distribution/v/ck12-org-normal-distribution-problems-empirical-rule but if you really want the right answer to a specific problem without fooling around with 68 - 95 - 99.7 use http://davidmlane.com/...
March 28, 2016

How on earth
did you get from such a simple first problem to the problem that messes up people who write papers on this sort of thing ?
March 27, 2016

probability
LOL this is why it is so hard to do this sort of test more positives will be due to that 10% wrong accuracy problem than due to having allergy. out of 1000 people, 10 have allergy out of these 10 who have it .9 * 10 = 9 test positive correctly 1 gets missed out of the 990 who ...
March 27, 2016

Hey, careful !
first .25^5 = .0009765 NOT what you got This is a BINOMIAL DISTRIBUTION P(5,k) = C(5,k)p^k (1-p)^(5-k) here p = .25 and 1-p = .75 Now the problem 3 right: C(5,3) = 5!/[3! 2!] = 5*4/2=10 P(5,3) = 10 * .25^3*.75^2 = .0879 4 right C(5,4) = 5!/[4! 1!] = 5 P(5,4) = 5 * .25^4 * .75^...
March 27, 2016

physics
d = Vi t + (1/2) a t^2 Vi = 20 /3.6 = 5.56 m/s V final = 30/3.6 = 8.33 m/s oh well, I do not need the physics equation because Vaverage = (1/2)(5.56+8.33) = 6.94 m/s 6.94 m/s * 20 s = 139 meters
March 27, 2016

Chemistry
You are welcome.
March 27, 2016

Chemistry
note expands as pressure goes down and expands as temperature goes up so you can check if you have those ratios right.
March 27, 2016

Chemistry
T1 = 330 T2 = 380 1.02 * 2.2 / 330 = .789 * V2 /380 V2 = (1.02/.789)(380/330)(2.2) = 3.28 L
March 27, 2016

typo
P1 V1/T1 = P2 V2/T2
March 27, 2016

Chemistry
T1 = 57 + 273 T2 = 107 + 273 P1 V1/T1 = P2 V2/T1
March 27, 2016

math
you ate 4/12 = 1/3 of the area so you ate (1/3) pi (49) 2/3 of the circumference is left (2/3)(pi)(14)
March 27, 2016

math
sure, why not 12 15/24 6 9/24 5 16/24 ---------- add 23 40/24 well 40 = 24 + 16 so regroup 23 + 24/24 + 16/24 24 + 2/3 because we already know 2/3 = 16/24 24 2/3
March 27, 2016

Are you there?
It is really important that you get both of my answers.
March 27, 2016

Statistics
let me do one point so you can see if an error p of 2 right for example P(10,2)= C(10,2) (.25)^2 (.75)^8 but C(10,2) = 10![2! 8!] = 10*9/2 = 45 so P(10,2) = 45 (.0625)(.1) = .282 does that agree ?
March 27, 2016

Statistics
yes, p = .25 the mean better be ten/4 :) which is 2.5 This is a binomial distribution mean = n p = 10 * .25 = 2.5 (remarkable :) sigma^2 = n p (1-p) =10 (.25)(.75) = 1.875 sigma = sqrt 1.875 = 1.37
March 27, 2016

physics
v^2/R = 9.24^2/18.4 = 4.64 m/s^2 centripetal acceleration so apparent weight on road = m (g-4.64) = 1800 (9.81 - 4.64) = 9306 N
March 27, 2016

physics
http://www.jiskha.com/display.cgi?id=1459109572
March 27, 2016

physics
Tension holds the weight T = 1.3 * 9.81 = 12.75 N The force on the puck is the tension, 12.75 N 12.75 = m v^2/R v^2 = 1.4 * 12.75 /.24 v = 8.63 m/s
March 27, 2016

Algebra
18 / 8 = 2.25 half lives 1 unit *(1/2)^2.25 = .210 unit left
March 27, 2016

science help PLS
because the water treatment plant may be taking water from a surface reservoir or be missing contaminants at the well field that are present in your aquifer.
March 26, 2016

science help PLS
I think A
March 26, 2016

chem
200 C = 373 K 20 C = 293 K P1 / T1 = P2 / T2 or P2 = P1 T2/T1 = 5.7 (293/373)
March 26, 2016

physics
x = xo + Vo t + (1/2) a t^2 72 = (1/2) a (36) a = 4 m/s^2 v = Vo + a t at t = 6 v = 0 + 4*6 v = 24 m/s that is initial Vo at 6 if there is no friction, it continues at 24 m/s for 6 s 24 * 6 = 144 m more
March 26, 2016

math
DRAW IT !!!!! First the triangle on the left (2,3), (8,3), (8,11) base = 6, altitude = 8 so area = 3*8 = 24 Now the right side, the hard part First rectangle (8,3)(8,11)(11,11)(11,3) that area = 3*8 = 24 subtract the triangles top and bottom top is (8,11)(11,7)(11,11) area top...
March 26, 2016

math
p good = .2 p not good = .8 this is a binomial distribution problem P(n,k) = C(n,k) p^k (1-p)^(n-k) where C(n,k) = n!/[k!(n-k)!] here for example P(10,1) = C(10,1).2^1 .8^9 C(10,1)= 10!/[1(9)!] = 10 so P(10,1) = 10 * .2 * .8^9 = .268 similarly C(10,2) = 10!/[2(8!] = 10*9/2 =45...
March 26, 2016

mathematics
Oh, I see, it is math, well check physics below.
March 26, 2016

not physics
We physicists have trouble with this sort of thing. ja + jo = 25 (ja - 8) = 2 (jo-8) ---------------------- well then ja = (25-jo) so (25 - jo - 8) = 2 jo - 16 17 - jo = 2 jo -16 3 jo = 33 jo = 11 I guess ja = 25-11 = 14 then
March 26, 2016

trigonometry
height + hypotenuse height = 10 tan 60 hypotenus = 10/cos 60 = 20 so 17.32 + 20 = 37.32 meters
March 26, 2016

TRIGONOMETRY
csc = 1/sin so sin = 1/ csc sin^2 = 1/csc^2 cos^2 = 1 - sin^2 = 1 - 1/csc^2 so tan^2 = sin^2/cos^2 = (1/csc^2)/[1-1/csc^2] tan^2 = 1/[csc^2 - 1] tan = sqrt (1/[csc^2 - 1] )
March 26, 2016

math
yes = 1.31 / 31200 = 4.2*10^-5 = .000042
March 26, 2016

geometry
I have no idea what your cone looks like but to find the volume of anything with straight sides and a pointy top multiply the base area by the height and divide by 3
March 25, 2016

physics
mu * normal force = m g normal force = m omega^2 R so m g = mu m omega^2 R mu = g/(omega^2 R) or as we could have guessed mu = gravity acceleration/centripetal acceleration mu = 9.81/[ 4.2^2 * 3.1 ]
March 25, 2016

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