Wednesday

January 28, 2015

January 28, 2015

Total # Posts: 20,428

**physics**

F = m v^2/r
*September 30, 2014*

**Algebra**

Yes.
*September 30, 2014*

**Algebra**

(-7,3) I think I do not do interval notation either.
*September 30, 2014*

**Algebra**

(x+2) < 5 and -(x+2) <5 x < 3 and (x+2) > -5 x < 3 and x > -7 which is -7 < x < 3
*September 30, 2014*

**Physics-Intro**

good grief, I have not seen those units for a while still F = m a force and weight in pounds, mass in slugs acceleration in ft/s^2 F = 25,000 * 28 = 700,000 pounds
*September 30, 2014*

**physics**

.424 * 10^8 m/s = 4.24 * 10^7 or a bit over a tenth of the speed of light.
*September 30, 2014*

**Algebra 2 Answer Check**

2 y = -5 x + 8 y = -(5/2) x + 4 slope = -5/2 so slope of perpendicular = 2/5 y = -(2/5) x + b 3 = -(2/5)5 + b 3 = -2 + b b = 5 y = -(2/5) x + 5
*September 30, 2014*

**Algebra 1**

1 a try x = -1 1 </= -1 nope b x = -1 works but x = 10 fails totally c x^2 </= 23.25 x^2 x^2 always + so this works by the way d is 4 x^2 -24 x + 36 >/= 4 x^2 - 3 -24 x + 39 >/= 0 nope
*September 30, 2014*

**Typo**

If you are really serious about only 11 meters^2 then (w+6)w = 11 w^2 + 6 w - 11 = 0
*September 30, 2014*

**Physics**

F = m a Ft = tug force = - Fa asteroid force 3360 vt + 6300 va = 0 momentum remains 0 490 = 3360 at -490 = 6300 aa at = .146 m/s^2 aa = -0.778 m/s^2 vt = 0 + .146 t va = 0 - .778 t position t = .5 (.146)t^2 430 - position a = .5 (-.778)t^2 they are headed toward each other so ...
*September 30, 2014*

**Trigonometry**

if theta is between 0 and -90 (quadrant 4) the sin is negative. Therefore we only look at quadrant one. sin^-1 0.95 = 71.8 degrees
*September 30, 2014*

**chemistry**

first balance 2 NaClO + H2O --> 2 Na+ +2OH- + Cl2 + O2 How many mols of NaClO ? Na = 23 g/mol Cl = 35.5 O = +16 so NaClO = 74.5 g/mol 2 NaClO = 149 g then grams of NaClO = .0585 *1.12*15 = .983 grams of NaCl .983/74.5 = .0132 mols of NaClO we get half as many mols of O2 so ...
*September 30, 2014*

**Algebra**

L = w + 4 L w = 165 (w+4)w = 165 w^2 + 4 w - 165 = 0 (w+15)(w-11) = 0 w = 11
*September 30, 2014*

**Physics**

phase 1 v = 5 t , slope up of 5 up to Vi = 25 phase 2 v = constant = 25 from t = 5 to t = 20 phase 3 v = 25- 5(t-20), slope down of -5
*September 30, 2014*

**Pre-Calculus/Trigonometry**

You are welcome :)
*September 30, 2014*

**Pre-Calculus/Trigonometry**

would it be like this for a, and if so how would i continue that? (f o g)(x)= 1/[(f o g)(x)-5]? ======================= no, just do what it says f (g(x)) use g(x) = (x^2+2) for argument of f in other words f (x^2+2) = 1/[ (x^2+2) - 5 ]
*September 30, 2014*

**Pre-Calculus/Trigonometry**

replace x by x^2+2 1/[ (x^2+2) -5 ] = 1/(x^2 - 3) b. f(6) = 1/1 = 1 g(1) = 1+2 = 3
*September 30, 2014*

**precal**

9 9r 9r^2 9r^3 -72 = 9 r^3 r^3 = -72/9 now work back a9 = 9/r a8 = 9/r^2 a7 = 9/r^3 interesting a7 = 9/r^3 = (9)(-9/72) = -81/72
*September 30, 2014*

**physics**

I could swear I did this one yesterday :( ball 1 d = distance down d = .5 g (t+1)^2 ball 2 d = 40 t + .5 g t^2 so .5 g (t^2 + 2 t + 1) = 40 t + .5 g t^2 put in whatever you use for g (9.81, 9.8 or 10) and solve the quadratic
*September 30, 2014*

**ALgebra 2**

From 0 go left 1/2 then go left another 3/4 see that you are now at -1 1/4
*September 30, 2014*

**ALgebra 2**

-2/4 - 3/4 = -5/4 = -1 1/4 Sketch this on a number line !!!!
*September 30, 2014*

**mathematic**

p = r - c p = 150 n - 850 - 76 n p=74n-850
*September 30, 2014*

**math exponential function**

450 (1.06)^(2n) = 477 1.06^2n = 1.06 n = 1/2 year
*September 30, 2014*

**Calculus**

ln y = x ln 2 1/y dy/dx = ln 2 dy/dx = y ln 2 or dy/dx = 2^x ln 2
*September 28, 2014*

**physics**

time for first rock -20 = -5 t^2 t = 2 seconds to fall so t for second ball = 2 - 1 = 1 second -20 = -Vi t + -5 t^2 20 = -Vi + 5 Vi = -15 m/s (the - sign means speed is down)
*September 28, 2014*

**physics**

Da = Db same distance total time a = time b + delay b we want time b Car A accelerate phase: vi = aA delayb Di = .5 aA delayb^2 constant speed phase Da = Di + vi t = .5 aA delayb^2 + aA delayb timeb Car B Db = .5 aB timeb^2 now Da=Db so .5 aA delayb^2 + aA delayb timeb = .5 aB...
*September 28, 2014*

**physic**

first vertical problem 45 = 4.9 t^2 t = 3.03 seconds to fall distance ball is from building = 3.03*5 = 15.15 distance man must run = 15.15 - 6 = 9.15 time man has = 3.03-.3 = 2.73 seconds 9.15 = .5 a (2.73)^2 solve for a
*September 28, 2014*

**trigo**

cos 3 x = 4 cos^3 x - 3 cos x
*September 28, 2014*

**SCIENCE - PLEASE HELP PLESE**

4) Multiply 4.135 x 4.688 888 887 m x 8.7m round your answer to the correct number of significant figures. ============================ You only have 2 sig figs because you said 8.7 not 8.70000000 so 19.388555555 is 19 <-------answer
*September 28, 2014*

**SCIENCE - PLEASE HELP PLESE**

3) Round 3155.24m, 8.777 73 cm, and 93.775 57 kg to one less significant figure than they each have currently. ==================== 3155.24 4 is less than 5 so 3155.3 3<5 so 8.7777 93.77557 7>5 so 93.7756
*September 28, 2014*

**SCIENCE - PLEASE HELP PLESE**

2) Find the weight of a 12.25 kg dog. Round your answer to the correct number of significant figures. Use weight=massxfree-fall acceleration. g is different in different places on earth. We need it to four significant figures because your mass is to four sig figs. I will call ...
*September 28, 2014*

**SCIENCE - PLEASE HELP PLESE**

1) Round 578.683 m, 47.3333 kg, and 789.5 cm to four significant figures. 0,1,2,3,4 round down 5,6,7,8,9 round up 578.6 83 8 is greater than 4 so this becomes 578.7 meters 47.33 33 3 is less than 4 so this becomes 47.33 kilograms 789.5 cm This already has four significant ...
*September 28, 2014*

**trigo**

h = L (1-cos T) geometry exact cos 2A = 1 - 2 sin^2 A identity so cos T = 1 - 2 sin^2 (T/2) h = L [ 1 - (1 -2 sin^2 (T/2) ] = L [2 sin^2 (T/2) ] = 20 sin^2 (T/2)
*September 28, 2014*

**physics**

2.4*84
*September 28, 2014*

**physics**

84*.24
*September 28, 2014*

**geometry**

height = h = 280/40 V = (1/3)(40)(h) the volume of any pointy thing with straight sides = (1/3) base area * height
*September 28, 2014*

**math**

in the ten based number system: To multiply by ten, add a zero To divide by ten, move decimal point one space left 200 / 10 = 20.0 = 20
*September 27, 2014*

**physcis**

.926 = (1/2)(9.8) t^2 solve for t u = 18.3/t
*September 27, 2014*

**physics**

r = 33*10^6 + 6.37*10^6 2 pi r = circumference of orbit v = 2 pi r/(24 h * 3600 s/h) Ac = v^2/r
*September 27, 2014*

**physics**

1.1 = Vi t - 4.9 t^2 t = 4.4/u but u = Vi because tan 45 = 1 1.1 = u t - 4.9 t^2 1.1 = u t - 4.9 (4.4^2)/u^2 1.1 u^2 = u^2 (4.4) - 94.9 3.3 u^2 = 94.9 u = Vi = 5.36 m/s sqrt(u^2+Vi^2) = 7.58 m/s
*September 27, 2014*

**physics**

45 F = 30*(45-15)
*September 27, 2014*

**physics**

200*10^3 = .2*10^6 m high R earth = 6.38*10^6 so R = 6.58 * 10^6 meters G = 6.67384 × 10-11 m3 kg-1 s-2 earth mass = Me = 5.97*10^24 kg m v^2/R = G Me m /R^2 v^2 = G Me/R = 6.67 * 5.97 /6.58 * 10^(-11+24-6) = 6.05 * 10^7 = 60.5 * 10^6 so v = 7.78*10^3 = 7,780 m/s (PART B...
*September 27, 2014*

**physics**

a = change in velocity / change in time = -16.7 / t t = distance/ average speed = .67/8.35 = .0802 second so a = -16.7 / .0802 = -208 agree F = m a = 42 * -208 = -8736 Newtons AGREE
*September 27, 2014*

**Math**

Try the rest now.
*September 27, 2014*

**Math**

10 balls at start 1 prob black, white, red = 3/10 * 4/9 * 5/8 2 prob black, red, white = 3/10 * 5/9 * 4/8 same as above 3 prob white, black, red = 4/10 * 3/9 * 5/8 same again 4 prob white, red , black same 5 prob red , white, black same 6 prob red, black, white same so 6 * 3/...
*September 27, 2014*

**Engineering science**

fresh water is about 1 kg/Liter so m g h/t = 9000 kg * 9.81 * 70/3600 seconds = 1717 Watts done = 1717 Joules/second * 3600 seconds/hr = 6,180,300 Joules/hour = 1717Joules/second*60 s/min = 103,020 Joules/min
*September 27, 2014*

**science**

3000*1 = F = 4000 * x x = .75 m/s^2
*September 27, 2014*

**chemistry**

. 4 mol/liter = .0004 mol/mL 30 * .0004 = 0.012 mol NaOH .012 mol NaOH in 100 mL is .12 mol/liter
*September 27, 2014*

**physics**

Gravitational force = G mplanet m/d^2 G = 6.67384 × 10-11 m3 kg-1 s-2 so FB = 6.67384 × 10-11 m3 kg-1 s-2 MB*6930/(3.01*10^6)^2
*September 27, 2014*

**physics**

FB = G MB 6930/(9*10^12) FA = G MA 6930/(9*10^12) MA = (9*10^12/6930 G) FA MB = (9*10^12/6930 G) FB ---------------------------- MA - MB = (9*10^12/6930 G)(FA-FB)
*September 27, 2014*

**chemistry**

100 (4.78/6.67)
*September 27, 2014*

**math**

multiply first equation by 6 6 x + 30 y = 36 6 x - 15 y = 18 --------------- subtract 45 y = 18 y = 18/45 = 6/15 x = 6 - 5 y x = 6 - 2 x = 4
*September 27, 2014*

**chemistry**

check, yes they add to 100 well, let's say we have 100 grams of this stuff Then we have 62.04 grams of C 62.04 / 12 = 5.17 mols of C 10.41 mols of H 27.55/16 = 1.72 mols of O 10.41/5.17 = 2.01 so 2 H for every C 10.41/1.72 = 6.05 so 6 H for every O 3C 6H 1O or C3H6O which ...
*September 27, 2014*

**Physics**

2 pi radians is a revolution so 8 pi radians is four revolutions
*September 27, 2014*

**Algebra 2**

one out of 50 bears caught is tagged so 50 * 50
*September 27, 2014*

**math**

distance flown = 16/cos 60 = 32 km 32 km/(1/60)hr = 60 * 32 = 1920 km/hr
*September 27, 2014*

**chemistry**

mol of NO2 mass = 14+32 = 46 grams/mol mol of N = 14 100 * 14/46 = 30.4%
*September 27, 2014*

**Algebra 2**

There must be more to this problem than just (y-1)/(x+3) = -3/4 That is the equation of a straight line 4 y - 4 = -3 x - 9 4 y = -3 x - 5 y = -(3/4)x - 5/4
*September 27, 2014*

**math**

a60 = a1 + (59)(7) a60 = -15 + 413 = 398 S60 = 60 (-15 + 398) / 2 =11490
*September 27, 2014*

**Math one question?**

350 +225 ----- =575
*September 27, 2014*

**physics**

power stage v = Vi + a t v = 0 + 25 * 3.77 v = 94.25 m/s when fuel runs out h = 0 + 0 t + (1/2)(25)(3.77)^2 h = 177.7 meters high when fuel runs out Coasting stage, Hi = 177.7 meters and Vi = 94.25 m/s then at top v = 0 0 = 94.25 - 9.81 t t = 9.61 seconds coasting up h = Hi + ...
*September 26, 2014*

**Pre-Calc**

(f+g)(x) = x + x + 2 - 2 = 2 x do the others the same way
*September 26, 2014*

**Science-HELP?**

at least it works until the sea rises a little :(
*September 26, 2014*

**Science-HELP?**

sure, that works
*September 26, 2014*

**physics**

I answered that. http://www.jiskha.com/display.cgi?id=1411686019
*September 25, 2014*

**Physics**

Horizontal F = m v^2/r Vertical Fmax = m g + mv^2/r m g + m v^2/r = 1.16 m v^2/r g = .16 v^2/r .16 v^2 = 9.8(.7) solve
*September 25, 2014*

**Match**

162 + 284 is something like 140 + 300 which is 440 you don't need 98 to get to 500 from there
*September 25, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*September 25, 2014*

**Algebra 1**

.91 = sum of first 6/6 so sum of first 6 =5.46 sum of first seven then is 5.46 + x so (5.46 + x)/7 >/= .92 5.46 + x >/= 6.44 so x >/= .98
*September 25, 2014*

**Algebra 1**

you can not just say less than 90 because you must include 90 therefore less than OR EQUAL TO 90
*September 25, 2014*

**Algebra 1**

Because It could be EXACTLY 80 or EXACTLY 90
*September 25, 2014*

**Algebra 1**

top will get 90 bottom will get 80 so what do you think?
*September 25, 2014*

**math...**

looks good to me.
*September 25, 2014*

**physics**

acceleration = change in velocity / change in time = (35 - 65) / 4.2
*September 25, 2014*

**Physics**

a = -9.81/4 = -2.45 m/s^2 0 = 6 - 2.45 t t = 2.45 seconds d = Vi t + (1/2) a t^2 d = 6 (2.45) - 1.23 (2.45^2) d = 7.31 meters
*September 25, 2014*

**Physics**

m v1^2/r = (9) m v2^2/r v2^2/v1^2 = 1/9 v2/v1 = 1/3
*September 25, 2014*

**math**

2. y + 2y + 3z combine like terms y + 2 y = 3 y so 3 y + 3 z B. 3y + 3z =================== Hey, you got the first one right. This is really no different 3. 6r + r - 5r (6+1-5)r = 2r A. 2r ========================= 4. 5x + 2(x + 6) is 5 x + 2 x + 12 or 7 x + 12 C. 7x + 12...
*September 25, 2014*

**Physics**

v1^2/r1 = v2^2/r2 v1^2/v2^2 = r1/r2 v1/v2 = sqrt (r1/r2)
*September 25, 2014*

**Physics**

weight = k r^3 drag = c r^2 v^2 at terminal speed, drag/weight = 1 drag/weight = const v^2/r so V1^2/R1 = V2^2/R2 V2^2/V1^2 = R2/R1 V2/V1 = sqrt (R2/R1)
*September 25, 2014*

**Algebra**

[(-3 x + 2 )(-2) -14 ]/6 [(6 x - 4 ) -14 ]/6 [6 x -18 ]/6 x - 3 write it down add three and you get x back :)
*September 25, 2014*

**Calculus**

f(x+h) = (x+h)^2 + x + h = x^2 + 2 h x + h^2 + x + h f(x) = x^2 + x slope = [f(x+h) - f(x) ]/h = [ 2 h x + h^2 + h ]/h = 2 x + h + 1 now at the point x = -1, h --->0 and slope = 2 x + 1 which is -2 + 1 = -1 so form of tangent is y = -1 x + b now what is y at x = -1 y = (-1...
*September 25, 2014*

**Physics**

assuming the current is perpendicular to the swimmer heading, it has nothing to do with the problem. It just means she will land somewhere downstream of the starting point. distance = speed * time = 0.4 * 200
*September 25, 2014*

**Math**

0.0034 move decimal point two places to the left to divide by 100 in ten based number system.
*September 25, 2014*

**physics**

dv = 4 pi r^2 dr note(surface area * dr) dv/v = 4 pi r^2 dr / (4/3) pi r^3 =3 dr/r
*September 25, 2014*

**physics see question above**

been there, done that
*September 25, 2014*

**Physics**

first drop the ball to see how long it is in the air 7.5 = 4.9 t^2 solve for t now horizontal problem u t = 9.5 u = 9.5 / t
*September 25, 2014*

**physics**

a + g = 7 + 9.8 = 16.8 m/s^2 F = 15 (16.8) = 252 N , bag tears
*September 25, 2014*

**physic**

F = k Q1 Q2 / d^2 where k = 9 * 10^9
*September 24, 2014*

**physics**

a = - 9.8 m/s^2 v = Vi + a t = 0 - 9.8 t h = Hi + Vi t -(9.8/2) t^2 0 = Hi + 0 (3) - (9.8/2)(3)^2 4.9 (9) = Hi Hi = 44.1 meters high
*September 24, 2014*

**History on Middle Ages(PLEASE HELP NOW)**

They had religious issues? I thought those were pre-decided in Rome :)
*September 24, 2014*

**Math**

well, surely x = -5 then y = 4
*September 24, 2014*

**statistics**

mean = 2.34 sd = .2 z = + or - .03/.2 look for probability of being within z = +/- .15 of mean
*September 24, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*September 24, 2014*

**Physics MCAT, Help please**

original momentum = 6 * 4 = 24 final momentum = 2 * 8 + V * 4 16 + 4 v = 24 4 v = 8 v = 2 m/s
*September 24, 2014*

**Math**

all components the same x i + x j + x k d = sqrt (3 x^2 ) = x sqrt 3 so if d = 1 x = sqrt(3) /3 so (sqrt 3/3)(i + j + k)
*September 23, 2014*

**Science**

(-4+8)/2 = 2
*September 23, 2014*

**Physics**

x = Xi + Vi t + (1/2) a t^2 4200 = 0 + 7.2 t + (1/2) a t^2 but t = 4 * 60 = 240 seconds so 4200 = 7.2(240) + .5 a (240)^2 solve for a then v = Vi + a t v = 7.2 + a (240)
*September 23, 2014*

**math**

(.2)gal/.08 shed = 2.5 gal /shed 2.5 gal/shed * 4 sheds = 10 gallons
*September 23, 2014*

**Math**

-1^3 = -1 (--2^4) = -2^4 = -16 5*-1*-16 = 80
*September 23, 2014*

**Math**

4.5 * 175/3
*September 22, 2014*

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