Friday

April 18, 2014

April 18, 2014

Total # Posts: 16,157

**STATS**

55% are below x z = .1 ---> F(z) about .55 .1 = (x - 75.5)/10.3 x - 75.5 = 1.03 x = 76.5

**physics**

Lamda = c * T T = L/c f = 1/T = c/L f1 = 348/.766 = 454.3 Hz f2 = 348/.780 = 446.2 Hz difference beat frequency = 8.15 Hz period of beat frequency = 1/8.15 = .123 s

**Math(CHECK ANSWERS)**

You are welcome :)

**Math(CHECK ANSWERS)**

5. seven pounds otherwise fine

**math(HELP)**

.06*350 = .25*120 = 120/4 =

**Science**

growing fruit, I suppose including apples

**calculus**

1/x is the slope of ln x which is very high when x is small and small when x is big

**physics**

75 sin 31

**physics**

75 sin 31 which is about 38 m because sin 30 = 1/2

**Chemistry**

MgCl2 needs 2 Chlorine atoms for every Magnesium atom so .3

**chemistry**

Now with that information and knowing that a mole of any chemical weighs its gram molecular mass I think you can do the rest for example a mol of water, H2O has mass 2 H + O = 2(1) + 16 = 18 grams so for water 18 grams is 6*10^23 molecules is one mole

**chemistry**

A mol is 6*10^23 of anything, sort of like a dozen is 12 of anything so 3.50 x 10^21 atoms (1 mol of atoms/6*10^23 atoms) = (3.5/6) 10^(-2) = .58*10^-2 mol = 5.8 *10^-3 = .0058 moles

**Physics**

by the way I could have done that really quickly by saying that the average speed up was half the starting speed. h = (1/2)(5)(.51) = 1.28

**Physics**

Vi = 5 m/s a = g = -9.81 m/s^2 v = Vi - 9.81 t v = 0 at top so 0 = 5 - 9.81 t t = .51 seconds to top h = Hi + Vi t + (1/2)a t^2 h = 0 + 5(.51) - 4.9 (.51)^2 h = 2.55 - 1.27 h = 1.28 meters

**Physics**

did that just below.

**Physics**

before you hit the brakes you go: 20*.5 = 10 meters then Vi = 20 m/s a = - 10 m/s^2 v = Vi + a t v = Vi - 10 T 0 = 20 - 10 t t = 2 seconds to stop after hitting brakes x = Xi + Vi t + .5 a t^2 d = 10 + 20 t - 5 t^2 d = 10 + 40 - 20 d = 30 meters we stopped 5 meters before the dog

**Calc**

integral of T dt from t = 0 to t = 256 divided by 256 [ 20 t + (5.25/1.75) t^1.75 ] at 256 - at 0 divided by 256 at 0 it is 0 [ 20(256) + 3 (256^1.75) ] / 256 20 + 3 (256)^.75 = 20 + 3(64) = 212 interesting, boiling point of water

**Physics**

Yes, the negative is unreal and wrong. The trajectory is a parabola. It crosses the x axis twice. However the first crossing is in our imaginations. It is before the kid dropped the bag, as if the bag had been thrown up from the ground instead of starting 34 meters up with an ...

**Physics**

h = 0 Hi = 34 Vi = + 2.3 (1/2) a = -g/2 = -4.9 h = Hi + Vi t - 4.9 t^2 0 = 34 + 2.3 t - 4.9 t^2 4.9 t^2 - 2.3 t - 34 = 0 t = [ 2.3 +/- sqrt(5.29 + 881) ]/ 9.8 t = [ 2.3 +/- 29.8 ]/9.8 t = 3.27 OR -2.8 the negative t was when it would have been at ground on the way up if it wer...

**Physics**

33 * 77 + 130 answer to a divided by (1.80+ 33/60)

**Precalculus**

radius bottom = 1.25 radius top = 1.25 + 5 tan 4 diameter top = 2 * radius top

**physics**

momentum before = momentum just after Vb bullet v block and bullet .039 Vb = (2.78+.039)v = 2.82 v now work on potential and kinetic energy after kinetic just after = .5 * 2.82 v^2 potential when stopped at top = m g h =2.82 * 9.81 * .291 = 8.05 Joules so 1.41 v^2 = 8.05 v = 2...

**Physics**

You are welcome :)

**Physics**

Yes, negative acceleration = deacceleration change in velocity is negative

**Physics**

or reverse a boat engine while steaming forward :)

**Science**

d is the only chemical reaction implied so I agree with you.

**statistics**

p = .4 so (1-p) = .6 binomial distribution n = 6 k = 4 C(n,k) = n!/[ k! (n-k)! ] = 6!/[4!(2!)] = 6*5/ 2 = 15 P(n,k) = 15 * p^k * (1-p)^(n-k) =15 * .4^4 * .6*2 = .1152

**Calc**

3 (ln x) - e^x 3 ln 1 = 0 e^1 = e so e

**Calc**

3*integral dx/x - integral e^x dx need I go further?

**intermediate algebra**

(9,000 -x)(0.05) + x (0.1) = 650

**math**

http://www.jiskha.com/display.cgi?id=1391813662

**physics**

initial x momentum = 2.6 m initial y momentum = 0 final x momentum = 1.3 m cos T + V m cos A final y momentum = 1.3 m sin T + V m sin A T is theta, the cue ball angle from x and A is the 8 ball angle from x now right off we know that the initial y momentum was zero so the fina...

**math**

They share the point (-1,-2) the first one goes right from there with slope 2 and the second one goes left from there at slope 1

**math**

There is no solution involved here, that is just two straight lines that at (-1,-2)

**Algebra 2**

.5 * .65 + .5 *.32 = .325 + .16 = .485 check probability other player wins = .5 * .35 + .5*.68 = .515 sum = 1, good :)

**algebra & trigonometry**

150*eggs + 100*oz meat </= 300

**Southern Union**

How fast is it going when it leaves the roof? v = a T d = .5 a t^2 64 = .5 * 3.35 * t^2 so t = 6.18 seconds on roof v = 3.35 * 6.18 = 20.7 m/s leaving roof Vertical velocity leaving roof = -20.7 sin 20 deg = -7.08 m/s horizontal velocity roof to ground = 20.7 cos 20 = 19.5 m/s...

**math**

maybe you mean ( 3 - e)^1 dx ??? or maybe 3 dx - e^1 dx ??? anyway the power 1 changes nothing so it is maybe (3-e) dx which is (3-e) x + C ???

**statistics**

So if you criterion is that any student counts plus any female student or not then it is (8 + 7 + 5)/27

**statistics**

I have the same question but perhaps I I list the four categories that the 27 students fit into you can figure it out yourself: a) 7 males (not student) b) 8 male students c) 7 female students d) 5 females (not student) so males not student = 7/27 male students = 8/27 female s...

**Precalculus**

Make block matrix 6 by 6 for total of 36 possible outcomes. Then count how many satisfy your criteria. 1. I get 20/36 = 5/9 2. agree 3. 2/36 = 1/18 4. 1/6 * 1/6 = 1/36 5. 1/6 + 1/6 = 1/3

**Physics**

distance = rate * time calculate the two distances 98 * 2 = 64 * 2 = ------------then subtract since it says meters, not kilometers, multiply answer by 1,000

**Physics**

delta x = .05 * 10^-9 m m = mass of electron delta p = mass of electron * delta v delta x * delta p = hbar/2 delta x * m * delta v = h bar/2 delta v = hbar/(delta x * 2 * m electron)

**Physics**

weight = 5*9.81 max static friction force =5*9.81*.8 = 39.24 N 5*9.81 * .22 = 10.8 moving friction 39.24 - 10.8 = 5 a a = 5.69 m/s^2

**algebra 1**

6m^4/5 divided by 2m 3 m^3/5 or (3/5) m^3

**algebra 1**

3/a^5 divided by 3/a^2 3/a^5 -------- 3/a^2 multiply top and bottom by a^5 3 ---------- 3 a^3 so yes a^-3 or 1/a^3

**forces**

net Force = 9(1365-1350) mass = 9(64) + 9(69) so a = 9(1365-1350) /[9(64) + 9(69) ] a = 15/133 = .113 m/s^2 b) T - 9(1350) = 9(64)(.113) T = 12,215

**trigonometry**

tree/12 = 6/shadow so tree = 72/shadow

**Math**

we want d T/ds where T = r'(s)/|r'(s)| the unit tangent vector r'(s) = 1 i + 0 j |r'(s)| = 1 so T = i + 0 j dT/ds = 0 so k = 0

**science --- pls check my work!!!**

Liquids with high viscosity do not flow as well as liquids with low viscosity. honey - high viscosity water - low viscosity

**Physics**

potential due to -q = -kq/L potential due to 2Q = +2k q/(L^2+4.65^2)^.5 so if 1/L = 2/(L^2+4.65^2)^.5 2 L = sqrt(L^2 + 4.65^2) 4 L^2 = L^2 + 4.65^2 3 L^2 = 21.6 L = 2.68

**physics**

I have no idea what your figure looks like but in general this is a projectile problem You have a constant velocity normal to the E vector (which is constant between the plates) like horizontal speed in a projectile problem You have a F = q E problem in the direction of the E ...

**Physics**

54 km/95 = .5684 hr 54 km/118 = .4576 hr difference = .11 hr .11 hr * 60 min/hr = 6.647 min which is 6 minutes and 39 seconds

**whoops**

in general q/C here V = V1 + V2 = q/C1 + q/C2 V/q = (1/C1+1/C2) so Ceq = q/V = 1/(1/C1 + 1/C2) = C1 C2 /(C1+C2)

**MITx: 6.002x Circuits and Electronics**

to add capacitors in parallel Ceq = C1 + C2 because C = Q/V V the same, charges add to add capacitors in series q is the same on both in general V = C Q here V = V1 + V2 = C1 q + C2 q V/q = (C1+C2) so Ceq = q/V = 1/(C1 + C2)

**MITx: 6.002x Circuits and Electronics**

Moreover, I can not see the circuit !

**MITx: 6.002x Circuits and Electronics**

sorry, 8.01 and 6.0 anything are not subjects I respond to. Been there, done that. You are all on your own.

**physics**

mass on light side = M tension = T T-Mg = Ma T = Mg + Ma mass on heavy side = M+m (M+m)a = (M+m)g - T so (M+m)a = (M+m)g - Mg - Ma Ma + Ma + ma = m g (2 M+m)a = m g a = m g/(2M+m) which we could have guessed in the beginning :) Forces on m Reaction force up = F force down = m ...

**algebra**

in your units: Io = 10^-16 watts/cm^2 Db = 10 log (2.54*10^-5/10^-16) = 10 log (2.54 * 10^11) = 10 log 2.54 + 10 log 10^11 = 4.05 + 110 = 114

**physics**

2000 meters - 40 meters = 1960 meter fall vertical fall problem first 1960 = 4.9 t^2 t = 20 second fall so it has to go 200 meters horizontal in 20 seconds u = 200/20 = 10 m/s

**Payback periods**

cost per year = 32,000 + 55,000 = 87,000 revenue per year = 100,000 profit/year = 13,000 so after ten years you have made 130,000 but you have depreciated the property to zero 550,000 -130,000 = 420,000 invested and not paid back From now on you make 100,000-32,000 = 68,000 pe...

**physics**

potential energy when? at the top?

**Math**

465 y = 155 x - 35 y = (155/465) x - 35/465 y = (1/3) x - 7/93 when x = 0 y = -7/93 no matter what you do starting with -7/93 going up with a slope of 1/3 it will be hard to get an integer y

**physic**

That is not one.

**SS --- one question pls help asap!!!!!**

I do not think it is a very well worded question.

**SS --- one question pls help asap!!!!!**

People moved from farms I think looking for jobs, not so much for Harvard.

**math linear equation**

1 +3 +2 +3 2 -1 -3 -8 5 +2 +1 +9 go to http://www.gregthatcher.com/Mathematics/GaussJordan.aspx 2, -3, 5

**Math**

(y -1) = +/- 3 if y-1 = + 3 then y = 4 if y-1 = -3 then y = -2

**Math**

twice :)

**Math**

as written it is not a function but an equation that has two solutions 2 x - 5 = -4 x^2 4 x^2 + 2 x - 5 = 0 that is the zeros of the parabola y = 4 x^2 + 2 x - 5 which are x = [ -2 +/- sqrt (4 + 80) ]/8 = - .25 +/- 1.15 = -1.39 and + .90

**optimisation**

A = (1/2) pi r^2 + 2 r w perimeter = 2 r + 2 w + 2 pi r = 850 = 2 r(1+pi) + 2 w 425 = r(4.14) + 2 w 213 = 2.07 r + w w = (213 - 2.07 r) A = .5 pi r^2 + 2r(213 - 2.07r) A = 1.57 r^2 + 425 r - 4.14 r^2 2.57 r^2 -425 r = -A r^2 - 165 r = -A/2.57 r^2 - 165 r + 6806 = -A/2.57 + 680...

**Algebra**

10^3 = 1,000

**physics**

h = Hi + Vi t - 4.9 t^2 0 = Hi + 20 (8) - 4.9(64) 0 = Hi + 160 - 314 Hi = 154 meters

**Physics**

distance = 1000 meters average speed = 90/2 = 45 meters/second so it took 1000/45 = 22.2 seconds to stop acceleration = change in velocity/change in time a = (0 - 90)/22.2 = - 4.05 m/s^2

**PHYSICS**

17(12) + (1/2)(1.37)(144)

**physics**

average velocity = (Position at start - position at finish) which is a vector divided by time In x direction runner goes: 38 meters so velocity in x direction is 38/13 = 2.92 m/s in x direction

**Algebra**

if x = 0 then 3(0)^2 - 5(0) = 0 if x = -1 then 3(-1)^2-5(-1) =3*1+5 = 8 if x = 2 then 3(4)-5(2) = 12-10 = 2

**physics**

average velocity = (Position at start - position at finish) which is a vector divided by time In x direction runner goes: 38 meters so velocity in x direction is 38/13 = 2.92 m/s in x direction

**math**

.06 2/3 = (6 + 2/3)/100 = (20/3)/100 = 20/300 = 1/15

**Classical mechanics**

Hmmm, looks like an 8.01 problem

**physics**

You are welcome :)

**physics**

99 = 4.9 t^2 t = 4.495 s 10 * 4.495 = 44.95m = 45.0 m to nearest tenth

**physics**

no, velocity is a vector. I has both magnitude (speed) and direction (NE or SW or whatever). These two vectors are in opposite directions.

**physics**

so?

**physics**

Vi = 4 h = Hi + Vi t - 4.9 t^2 0 = 0 + 4 t -4.9 t^2 t = 4/4.9 = .816 seconds before it is back down .816 * . 7 = .571 meters Your cannonball is remarkably slow, typo?

**physics**

driver goes 30 t cop goes .5 a t^2 = 1.2 t^2 so 30 t = 1.2 t^2 t = 30/1.2 seconds or of course they are also together at t = 0 :)

**Calculus 3**

anyway that would put the center at x = -1 y = 1/2 z = -1/4

**typo?**

x^2+4??????y^2 ?????+2z^2+2x-4y+z = 20 if so x^2 + 2 x = -(+4y^2+2z^2-4y+z) + 20 x^2 + 2 x + 1 = -(+4y^2+2z^2-4y+z) + 21 (x+1)^2 = -(+4y^2+2z^2-4y+z) + 21 4 y^2 - 4 y = -(x+1)^2 -2 z^2 -z + 21 y^2 - y =(1/4)[-(x+1)^2 -2 z^2 -z + 21] y^2-y+1/4=(1/4)[-(x+1)^2 -2 z^2 -z + 22] 4(y...

**math**

L + 2 W = 120 so L = 120 - 2 W A = L W A = (120-2W)W = 120 W - 2 W^2 so 2 W^2 -120 W = - A W^2 - 60 W = -A/2 W^2 - 60 W + 900 = -A/2 + 900 (W-30)^2 = -(1/2)(A-1800) vertax of parabola at (30,1800) so W = 30 L = 120 - 60 = 60 and A = 1800 m^2

**Physics**

They both experience the same gravitational force, m g their acceleration is therefore F/m = g Period, no other force, no other acceleration.

**Physics**

222 * 530 = original momentum 4 v + 218 * 410 = final momentum original momentum = final momentum

**CHEMISTRY**

85.2 - 48 = 37.2 mg of X 4 X atoms for every 10 O atoms 10 * 16 = 160 4 * X = 4x 4x/160 = 37.2/48 4 X = 160 *37.2/48 X = 31 check 31 * 4 = 124 16 *10 =160 124/160 = .775 and 37.2/48 = .775 good

**Math**

X y = (5 - p) y = (5-p)/X

**Physics**

You are welcome :)

**Physics**

momentum before = momentum after .018*222 = .018*72 + 3.9 * v

**Physics**

weight component down ramp = m g sin T so m g sin T = m a 4.7 = 9.81 sin T sin T = .479 T = 28.6 degrees d = (1/2) a t^2 6.4 = 2.35 t^2 solve for t LOL - the mass cancels, no difference

**Math**

1/2 = 5/10 2/5 = 4/10

**math**

1 dog 2 cats 2/15 of a parrot 2/45 of a snake I suppose you mean to say 6 snakes for 7 turtles in which case 2/45 *7/6 = 7/135 turtles so cats/turtles = 2 /(7/135) = 270/7

**Math**

sin^-1 .7245 = 46.4 deg in quadrant 1 or in quadrant 2 180 - 46.4 = 133.6 deg

**Math**

sin^-1 .7245 = 46.4 deg in quadrant 1 or in quadrant 2 180 - 46.4 = 133.6 deg

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