Thursday

November 20, 2014

November 20, 2014

Total # Posts: 19,366

**Physics**

yes
*June 13, 2014*

**algebra**

1 and 2 that is 2/6 or 1/3 450/3 = 150
*June 13, 2014*

**Physics**

wait a minute, add the weight of the ball!. 10 + 10*9.81 = 108 N
*June 13, 2014*

**Physics**

You are welcome.
*June 13, 2014*

**Physics**

Force * time = impulse = change in momentum T (10) = 10 * 10 T = 10 N which by the way is about the weight of the ball on earth. I think it would take longer.
*June 13, 2014*

**physics**

distance = speed * time with no force in horizontal direction 65 = 14 t t = 4.64 seconds in the air In the vertical direction it simply falls a distance h h = (1/2) g t^2 = 4.9 (4.64^2) h = 106 m
*June 13, 2014*

**Physics**

80 cal = 335 joules so Lf = 335 Joules / .001 kg - 335,000 Joules/kg potential energy = m g h m g h = m (335,000) 9.81 h = 335,000 h = 34,149 meters
*June 13, 2014*

**PHYSICS**

2 pi radians every 60 seconds 2 pi/60 = pi/30
*June 13, 2014*

**Physics**

call side of square = 1 look at components along diagonal 2(1.1 *1.1 /1^2)cos 45 = 1.1 q/(sqrt2)^2 cos 45 = 1/sqrt 2 2(1.1) = q/sqrt 2 q = 2.2 sqrt 2
*June 13, 2014*

**Physics**

F = m a F = E q same for both where q = electron charge, + for proton, - for electron m = mass electron for electron m = mass proton for proton
*June 13, 2014*

**Science**

Something you do to get something going. https://www.google.com/search?q=stimulus+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb
*June 12, 2014*

**Math**

pi d^2/4 h (3.14 * 7.4*7.4 * 2.4 ) / 4
*June 12, 2014*

**MATH**

integral of e^(Lx)dx = (1/L) e^(Lx) + c
*June 12, 2014*

**Physics**

F = m a = -kx if x = A cos w t v = dx/dt = -Aw sin w t a = d^2x/dt^2 = -A w^2 cos w t = -w^2 x so -m w^2 x = -k x w^2 = k/m w^2 = 210/3 = 70 w = sqrt(70) = 8.37 when |x| = .23 , |v| = .72 .23 = A cos 8.37 t .72 = -A (8.37) sin 8.37 t so cos 8.37 t = .23/A sin 8.37 t = .086/A ...
*June 12, 2014*

**Physics**

North south problem 7.5 Vn = 4.5 (8.5 cos 30) -7.5(6.5 sin 20) East west problem 7.5 Ve = 4.5(8.5 sin 30) +7.5(6.5 cos 20)
*June 12, 2014*

**math equation**

1/3 + 1/4 = 4/12 + 3/12 = 7/12 right 12/12 - 7/12 = 5/12 right he has 5/12 left so 5/12 of salary = 400 multiply both sides by 12/5, the inverse 60/60 of salary = (12/5) * 400 = 12 * 80 = 960
*June 12, 2014*

**physics**

F = k x 10.5 = k (.72 k = 10.5 N/.72 m
*June 12, 2014*

**Science(electric circuits)**

Maybe the total current is the sum of the currents through the individual paths.
*June 12, 2014*

**Physics**

1/Req = 1/1 + 1/2 + 1/4 1/Req = 4/4 + 2/4 + 1/4 = 7/4 so Req = 4/7 The voltage is the same across all elements in parallel i for the 4 ohm = 6/4 = 1.5 amps P = i V or i^2 R = 1.5 * 6 or 2.25 * 4 = 9 watts
*June 12, 2014*

**Physics**

voltage across resistor = i R = 1.5*5 = 7.5 Volts voltage loss to internal resistance = 1.5 * .15 = .225 volts total voltage = 7.5 + .225 = 7.725 Volts
*June 12, 2014*

**physics**

.2 kw * 10 = 2 kw hr per day times 365 = 730 kw hr per year times .15 dollar/kw hr = $109.50 per year = $110 rounded to nearest dollar
*June 12, 2014*

**Science(electric circuits)**

If elements are in parallel, each sees the same voltage and the current is split up between them.
*June 12, 2014*

**physics**

100 * (.4/.05) = 800 N arms 0.4 meters long? That is one big nut cracker.
*June 12, 2014*

**physics**

F * 10 = 600 * 4 F = 600 * .4 = 240 N if you tried to lift at the other end F2* 10 = 600 * 6 F2 = 360 N
*June 12, 2014*

**physics**

http://www.jiskha.com/display.cgi?id=1402590278
*June 12, 2014*

**Science(electric circuits)**

voltages across individual elementsd add in a series circuit.
*June 12, 2014*

**Science(electric circuits)**

If you take one element out of a series circuit, no current can flow and all elements lose power. Remember the old Christmas tree lights that were wired in series? If one went out, they all went out.
*June 12, 2014*

**Science(electric circuits)**

If devices are wired in series, the same current goes through each of them.
*June 12, 2014*

**science (help)**

water, fresh and salt.
*June 12, 2014*

**Algebra**

clark + clark + 5 = 33 2 clarks = 28 clark = 14 so shelly = 19
*June 12, 2014*

**Math**

6x,xx5 so 11 + 3 x = 23 3 x = 12 x = 4 64,445
*June 12, 2014*

**Physics**

south 7-3 = 4 east 7-4 = 3 d = sqrt (9+16) = 5km tan theta = 3/4 where theta is angle east of south theta = 36.9 deg east of south or 180 -36.9 = 143.1 on your compass clockwise from north
*June 12, 2014*

**Physics**

no idea, depends on coef of friction between road and man's shoes.
*June 12, 2014*

**physics**

Take moments about foot of ladder of length L 200 (L/2) sin 30 = F L sin 60 50 = F sin 60 F = 57.7 N
*June 12, 2014*

**Math**

area of layer = pi D^2/4 = 3.14 (49/4) = 38.465 in^2 8 layers = 307.72 in^2 divide by 55 5.6 batches so make 6
*June 12, 2014*

**Introductory Algebra**

Ah, what was that exchange rate ?
*June 11, 2014*

**algebra**

3 pounds of tin = 3(c+2) dollars 7 pounds of copper = 7 c dollars 10 pounds of bronze = 38.50 dollars so 7 c + 3 c + 6 = 38.5 c = 3.25 dollars per pound for copper so c+2 = 5.25 dollars per pound for tin
*June 11, 2014*

**math**

infinity
*June 11, 2014*

**Math help!**

let z = ln(5x) d/dx tan z = sec^2 z dz/dx but dz/dx = d/dx ln(5x) = (1/5x)5 = 1/x so (1/x)sec^2(ln(5x))
*June 11, 2014*

**Math help!**

I have a hunch you mean: (x^4+x^2+1)/(x^2+1) (bottom d top - top d bottom)/bottom squared [ (x^2+1)(4x^3+2x) -(x^4+x^2+1)(2x)]/(x^2+1)^2 [4x^5+6x^3+2x-2x^5+2x^3+2x]/(x^4+2x^2+1) [2x^5+8x^3+4x]/(x^4+2x^2+1
*June 11, 2014*

**Math**

You are welcome :) By the way, the only tricky thing on this general subject is that if you multiply (or of course divide) both sides by a negative number, reverse the direction of the arrow.
*June 11, 2014*

**Math**

Does your symbol mean greater than or equal to? If so: y - 6 >/= 12 add 6 to both sides y >/= 18
*June 11, 2014*

**math please help!**

d/dx [e^-(3x) ] [ sin (4 x) ] = [e^-(3x) ] d/dx [ sin (4 x) ] + [ sin (4 x) ] d/dx [e^-(3x) ] = [e^-(3x) ][4 cos (4x) ] + [ sin (4 x) ][ -3 e^-(3x) ] = e^-(3x)[ 4 cos (4x) -3 sin (4x) ]
*June 11, 2014*

**HISTORY**

Well, we agree about Atlanta to the sea :)
*June 11, 2014*

**HISTORY**

12. Check your MAP !
*June 11, 2014*

**HISTORY**

Lincoln put off the proclamation until the Union won a battle, Antietam.
*June 11, 2014*

**HISTORY**

9. agree 10. The border states mostly allowed slavery. Therefore there were by definition differences of opinion on the subject in the Union camp.
*June 11, 2014*

**HISTORY**

( I was born in Maryland :)
*June 11, 2014*

**HISTORY**

NO !!!!!!!!!!!!! Virginia was a free state that surrounded Washington, D.C., on the west and south. *** NO !!!!!!!!!!!!!!!!!!!!!!, a million times NO !!!! and MARYLAND WAS a SLAVE STATE that stayed in the union
*June 11, 2014*

**physics**

Do the vertical problem first Vi = initial speed up then v = Vi - g t at top, v = 0 0 = Vi - g t Vi = g t t = Vi/g h = 0 + Vi t - .5 g t^2 14 = Vi^2/g - .5 Vi^2/g 28 g = Vi^2 Vi = sqrt (28 g) Vi = 16.6 m/s Vi = v sin theta 16.6 = 24 sin theta so ....
*June 11, 2014*

**Physics**

yes (1/2) m v^2 = m g h so h = (1/2) v^2/g
*June 11, 2014*

**math (check answer plz)**

permutations of 8 taken in groups of 3 = 8!/(8-3)! = 8!/5! = 8*7*6 = 336 yes
*June 11, 2014*

**algebra**

n * 1.35 = 1600 + .41 n + 3700 .94 n = 5300
*June 11, 2014*

**math *check* (PERMUTATION)**

3 * 2 * 1 = 6
*June 11, 2014*

**physics**

72/3.6 = 20 meters/second (helpful to remember 1000 meters /3600 seconds = 1/3.6) 0 = 20 + a t t = -20/a x = Xi + Vi t + (1/2) a t^2 200 = 0 + 20 t + .5 a t^2 200 = 0 -400/a + .5 a (400/a^2) 200 a = -400 + 200 a = -1 so d, retardation of 1 m/s^2 ------------------------ ...
*June 11, 2014*

**physics**

d/2 = 30 t1 so t1 = d/60 d/2 = 50 t2 so t2 = d/100 t = t1 + t2 d = v (t1+t2) = v (d/60 + d/100) 100 = v ( 5/3 + 3/3) = (8/3) v v = 300/8 = 37.5 km/hr
*June 11, 2014*

**physics**

0 = 14.1 - 3.2 t as Janet told you below.
*June 11, 2014*

**Math**

probability of what? one one and the ten or two ones or what? I guess I will assume you mean what is the probability of getting ten plus one first draw, probability of ten = 1/5 if you missed, you now have three ones and a ten probability of ten = 1/4 so the total probability ...
*June 10, 2014*

**math**

http://www.jiskha.com/display.cgi?id=1402442232
*June 10, 2014*

**math**

I just did that
*June 10, 2014*

**Macroeconomic**

I doubt it.
*June 10, 2014*

**math (check answer plz)**

37 marbles? first draw (red) 6/37 second time (independent because you replaced the marble and still have 37 blue 8/37 so 6/37 * 8/37 = 48/1369 You multiply to get probability of two independent events both happening, you add if two things satisfy your condition such as if ...
*June 10, 2014*

**Math- urgent**

You do not. Those are functions of an ANGLE, not a triangle They are defined in a right triangle. If A is one of the two angles that is not 90 degrees then sin A = opposite side/hypotenuse cos A = adjacent side / hypotenuse tan A = sin A/cos A = opposite/adjacent
*June 10, 2014*

**math (please check answer)**

You are welcome.
*June 10, 2014*

**math (please check answer)**

probability of failure = 147/156 it has to be one or the other so 1 - 147/156 = 9/156 = 3/52 agree
*June 10, 2014*

**math**

a ar ar^2 ar^3 sum of first 4 = a (1-r^4)/(1-r) = 32.5 a r^3 = 3375 a r^3 = 3375 r = 15 a ( 1-r^2)(1+r^2) /(1-r) = 32.5 a (1+r)(1+r^2) = 32.5 a (16)(226) = 32.5 a = .0089878 about 1 cent :) ar = .1348 ar^2 =2.02 ar^3 = 30.33 about 30 dollars
*June 10, 2014*

**math**

alcohol removed = 1/10 liter first time = 1/10 (.9) liter second time = 1/10 (.9)(.9) third time .... =1/10 (.9)^6 seventh time so amount removed = .1 + .1*.9^1 +....1*.9^6 seven terms a = .1 sum removed = .1 (1-.9^7)/.1 = .478 so amount remaining = 1-.478 = .522
*June 10, 2014*

**Physics**

You are welcome.
*June 10, 2014*

**Physics**

110 km/hr = 110,000 m/3600 s = 30.6 m/s m g h = (1/2) m v^2 9.81 h = .5 (30.6)^2 h = 47.7 meters (b) loss of energy = m g (47.7-22) = 750(9.81)(25.7) = 189,000 Joules lost (c) work done = force in direction of motion * distance moved 189,000 = F (22/sin2.5) F = 375 N
*June 10, 2014*

**Math**

distance = speed * time 3.54 * 10^7 = 3*10^8 t t = 3.54/3 * 10^-1 t = 3.54 / 30 = 0.118 seconds
*June 10, 2014*

**math**

dp/dt = p/8 dp/p = .125 dt ln p = .125 t + c p = Po e^.125 t
*June 10, 2014*

**math**

1.08^10 = 2.16 2.16 * 10,000 = 21,589.25
*June 10, 2014*

**math**

a ar ar^2 ar^2 - a = 25 or a (r^2-1) = 25 ar^2 - ar = 15 or ar(r-1) = 15 [25/(r^2-1) ] r (r-1) = 15 r (r-1) /[ (r+1)(r-1) ] = 15/25 = 3/5 r/(r+1) = 3/5 5 r = 3 r + 3 2 r = 3 r = 3/2 = 1.5 then a r^2 - a = 25 1.25 a = 25 a = 20 so 20, 30, 45, .....
*June 10, 2014*

**Math**

You are welcome.
*June 10, 2014*

**Math**

2 = e^35 k ln 2 = 35 k k = .0198 so a = 1400 e^.0198*3*60 a = 1400 e^3.565 a = 49,475.2
*June 10, 2014*

**Physics**

area of loop = .02^2 = .0004 m^2 dB/dt = .044/.1 = .44 emf = A dB/dt = .0004 *.44 = 1.76 * 10^-4 = .00018 V
*June 10, 2014*

**Physics**

Seems to me they better repel each other so I agree with you.
*June 10, 2014*

**math (cant figure it out)**

11 numbers, 6 of which are even if you count 0 as even (there are evidently 10 spaces between numbers but 11 numbers) so 6/11 but the question is poorly worded.
*June 10, 2014*

**My Final Algebra 1 Question**

a. x must be greater than 0 (undefined for x = 0) so x = 0 is not in the domain (infinite number of teachers) y, must be greater than 2 so range is 2 to very large (for small cost per teacher.) If x is a dollar per teacher, then y = 202 which seems a reasonable upper limit. b...
*June 10, 2014*

**Physics**

I agree with 1/2
*June 10, 2014*

**math**

(a+b)/2 = 9 so a+b = 18 sqrt ( a b) = 3 sqrt 5 so a b = 9*5 = 45 well so b = 45/a and a + 45/a = 18 or a^2 - 18 a + 45 = 0 ( a-15)(a-3) = 0 a = 15 or 3 so one of them is 3 and one of them is 15
*June 10, 2014*

**HISTORY**

Lincoln issued the proclamation under his powers as commander in chief of the US military ass an act of war. He had no authority to remove property from people with whom we were not at war.
*June 10, 2014*

**math**

arithmetic mean = (10+40)/2 geometric mean = sqrt (10*40) = 20
*June 10, 2014*

**HISTORY**

From Wikipedia: In the mid and late 1840s, immigrants from Ireland and Germany streamed into the city, swelling the population of Philadelphia and its suburbs.[52] In Philadelphia, as the rich moved west of 7th Street, the poor moved into the upper class' former homes, ...
*June 10, 2014*

**math**

value = 1540 *(1/2)^(n/4) when n = 0, years, cost = 1540 for person 1 when n = 4 years, cost = 1540/2 for person 2 when n = 8, years, cost = 1540/4 for person 3 etc
*June 10, 2014*

**Maths**

Since it asks for depth wrt average, we do not need the 4 m average but only how much it departs from average at t = 0, d = -2 (low tide, 2 feet below average) d = -2 cos 2 pi t/T since T = 12 hours is given d = -2 cos (pi t/6)
*June 10, 2014*

**Algebra 1--Please, help me!**

(2x-20)(x+1) for example would be 2 x^2 - 18 x - 20 (2 x - 10)(x + 2) would be 2 x^2 - 6 x - 20 so 18 or 6 would work
*June 10, 2014*

**calculus**

(x+3)^2 = p (y-q) g = x + 7 when g = 0, x = A 0 = A + 7 A = -7 so A is 4 to the left of -3 therefore B is 4 to the right of -3 or at B = +1 so g = 7 at x = 0 so C = 7 A = (-7,0) B = (1,0) C = (0,7)
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

As far as I know, yes
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

Now wait a minute. Somewhere in your text book it says that if the denominator of a fraction is zero, that spot must be excluded from the domain of the function since the answer is undefined. Try dividing some number by zero on your calculator. Answer is "c". I had ...
*June 10, 2014*

**Algebra 1-- Please, check my answers!**

5. Which if the following is a true statement about the function y = 1/x? a. The domain is all real numbers. b. The range is all real numbers. c. The domain is all real numbers except 0. d. The range is all real numbers except 1. A: a? ============================= No, ...
*June 10, 2014*

**math**

Ah, two of us posted answers above.
*June 9, 2014*

**math**

change percent to decimal fraction by dividing by 100 so we mean .25 * 250 off 62.50 off 250 - 62.50 = $ 187.50 alternatively 100% - 25% = 75 % 75/100 = .75 .75 * 250 = $ 187.50 againg
*June 9, 2014*

**Algebra 1--Please, check my answer!**

When x = 6 (x-6) = 0 so y = 0 when x = 6 That is when it hits the x axis
*June 9, 2014*

**Algebra 1--Please, check my answer!**

If x = 6, bang if x = 6 bang so at ONE point x = 6 which is the vertex of the parabola. It just grazes the x axis and both roots are right there.
*June 9, 2014*

**Algebra II**

smallest = s biggest = b medium = m b = s + 90 m = s + 30 s + m + b = 180 s + s + 30 + s + 90 = 180 3 s = 60 etc.....
*June 9, 2014*

**Calculus**

yes
*June 9, 2014*

**Calculus**

See Baggins, Bilbo, "There and Back Again".
*June 9, 2014*

**Calculus**

Your velocity is zero at t = 3 !!!!! right in the middle of your range. It reversed direction midstream You calulated displacement (where it moved to which was nowhere) instead of how far it went (distance moved) do t = 0 to t = 3 then t = 3 to t = 6 add the ABSOLUTE VALUES
*June 9, 2014*

**physics**

How much energy should it have? m g h = 1.6 * 9.81 * 2.9 How much does it have? (1/2) m v^2 = (1/2) * 1.6 * (2.8)^2 so subtract
*June 9, 2014*

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