Thursday

October 2, 2014

October 2, 2014

Total # Posts: 18,776

**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*

**math**

she painted 3/4 of 1/3 = 1/4 of the total wall what was left is 1/3 -1/4 = 4/12 -3/12 = 1/12 is bare still
*September 22, 2014*

**physics**

100 + 273 = Th 60 + 273 = Tc 100 * (Th-Tc)/Th
*September 22, 2014*

**Physics HUH ????**

Perhaps mass 2 is hanging from a pulley on earth and mass one is sliding on a frictionless horizontal table? If so force = m2 g mass accelerated = (m1+m2) F = m a m2 g = (m1+m2) a
*September 22, 2014*

**Math**

14+2m = 4m - 16 subtract 2 m both sides 14 = 2 m - 16 add 16 both sides 30 = 2 m multiply both sides by (1/2) 15 = m ================================ 4(x +2) = 14 - 2(3 - 4x) 4 x + 8 = 14 - 6 + 8 x 8 + 6 = 14 + 4 x 0 = 4 x x = 0 =========================== Eight subtracted ...
*September 22, 2014*

**Basic English - can not see underlines**

"for" in "for all" is one if underlined
*September 22, 2014*

**college physics**

average speed during crash = 3.75/2 so time to stop = .794 / (3.75/2) acceleration = change in speed / change in time or a = (0 - -3.75) / [.794 / (3.75/2) ] and F = m a = 52.2 a
*September 22, 2014*

**English**

6. Do you mix father up with turpentine before you paint? Perhaps: Father and I are going to paint the walls. 10. Does the janitor's office fit in the garbage can? Perhaps: I am going to throw garbage into the garbage can near the janitor's office.
*September 22, 2014*

**What is the degree of this polynomial?**

You are welcome :)
*September 22, 2014*

**What is the degree of this polynomial?**

1+2+3+2 = 8
*September 22, 2014*

**math**

50*20 = 1000 square feet so we use 1680/1000 = 1.680 ft on pool 1.680 * 12 = 20.16 inches used but there is an easier way 30 in * (2100/1000) * .4*.8 = 20.16 in
*September 21, 2014*

**math**

1/8 + x = 1/4 x = 1/4 - 1/8 x = 2/8 - 1/8 x = 1/8 but I bet you already knew that 1/8 + 1/8 = 1/4 :)
*September 21, 2014*

**Physics**

that is what you said. A mass of 10 kg is a weight of 98.1 Newtons
*September 21, 2014*

**Physics**

weight = 10 * 9.81 = 98.1 Newtons = normal force max friction force = .3 * 98.1 Newtons Of course we are not allowed to push down on it :)
*September 21, 2014*

**Hey, I just did this**

but here is another reply from another teacher http://www.jiskha.com/display.cgi?id=1202595476
*September 21, 2014*

**PHYSICS**

LOL, again ? R = A V = L^2 L/T P = F/A = m L/T^2 / L^2 P = m L/ (T^2L^2) m = rho L^3 P = rho L^3 /(T^2 L) P = rho L^2/T^2 = rho v^2 4 by the way this does not give us the sign and rho is M/L^3 but is constant in the usual incompressible fluid problem
*September 21, 2014*

**Physics I**

v = Vi + a t here v = Vi - 9.81 t
*September 21, 2014*

**Physics I**

our acceleration is 9.81 DOWN, negative so our UP speed decreases g = -9.81 m/s^2 gravity does not push UP no matter if you are going up or down
*September 21, 2014*

**Physics I**

aaarrrggghhhh !!!! g is g is g is g = -9.81 m/s^2 so d when you throw a ball up, its speed up decreases until it stops ! The acceleration is 9.81 down until it comes back down and hits the ground.
*September 21, 2014*

**Physics**

u = 15 forever Vi = -20 h = Hi + Vi t + (1/2) a t^2 0 = Hi - 20 t - 4.9 t^2 but t = 4 so solve for Hi, initial height in 4 seconds at 15 goes 60 meters where is the basket at 4 seconds? h basket = Hi - 80 d = sqrt (60^2 + h basket^2)
*September 21, 2014*

**physics**

u = 22 cos 53.6 forever Vi = 22 sin 53.6 v = Vi - 9.8 t at top v = 0 0 = 22 sin 53.6 - 9.8 t solve for t, time to top h = 0 + Vi t - 4.9 t^2
*September 21, 2014*

**physics**

u = horizontal speed = 14.9 forever now vertical problem, simply drop from 7.05 m -h = -(1/2)gt^2 7.05 = 4.9 t^2 t = 1.2 seconds to fall how far horizontal in 1.2 seconds? x = 14.9 * 1.2
*September 21, 2014*

**Algebra**

average base = (3b-4+b)/2 = 2b-2 (2b-2)(b/2) = 210 b^2-b-210 = 0 (b-15)(b+14) = 0 b = 15 3b-4 = b/2 =
*September 21, 2014*

**physics**

t1 = 280/88 t2 = 210/75 all south so v average south = (280+210)/(t1+t2)
*September 21, 2014*

**physics**

change in x speed = 6.5 cos50-4.2cos34.5 change in y speed = -6.5 sin50-4.2sin34.5 ax = change in x speed/2 ay = change in y speed/2 a = sqrt (ax^2+ay^2) A = angle of a above horizontal tan A = ay/ax
*September 21, 2014*

**physics**

Vi = 0.43 v = Vi + a t v = 0.43 + 3(5)
*September 21, 2014*

**physics**

That is half a g for 5 minutes, way too gigantic but anyway v = Vi + a t here t = 5 * 60 = 300 seconds
*September 21, 2014*

**physics**

a = change in velocity / change in time = (6.5 -1.2)/25
*September 21, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*September 21, 2014*

**physics**

Boat 1 north velocity as seen from boat 2 = boat 1 north speed - boat 2 north speed 2.2 cos 47 = .745 - boat 2 north Boat 1 east as seen from boat 2 = boat 1 east - boat 2 east 2.2 sin 47 = 0 - boat 2 east
*September 21, 2014*

**Math-HElP PLEASE??**

2.25a + 1.75(300-a) = 613.5
*September 21, 2014*

**physics**

(1/2) m v^2 = m g h A.) v = sqrt (2 g h) = -sqrt (2*9.8*1.95) negative because down B.) (1/2)m v^2 = m g h or v = sqrt (2*9.8*1.87) positive because up) C.) change in velocity = (magnitude Part A + magnitude part Part B) divide that by .08 to get acceleration up D.) (1/2)(a ...
*September 21, 2014*

**Math**

is 111 prime? nope, 1,3, 37, 111 but 111 is certainly a factor of whatever our answer is 111*1 or 2 or 3 or whatever up to 9 so 3, 37 and what? How about 7 ? 777 = 7 * 3 * 37 10+37 = 47 sure enough
*September 21, 2014*

**history**

Shortage of supply over much of the Arabian Peninsula?
*September 21, 2014*

**physics**

U = 15 forever so d = u t now find t, time to fall 125 m 125 = 4.9 t^2 t = sqrt (125/4.9)
*September 21, 2014*

**Chemistry**

I agree with that.
*September 21, 2014*

**Chemistry**

You are welcome.
*September 21, 2014*

**Chemistry**

66.6 yards * 36 in/yard * 2.54 cm/in = L 12 in * 2.54 cm /in = w volume = w * L * t so 2.7 grams/cm^3 * w * L * t = 830 grams solve for t
*September 21, 2014*

**physics**

g is g is g
*September 21, 2014*

**Algebra**

(10 x + y) y = 2 + 4 x 13 + 3 (10 x + y) = (10 y + x) 13 + 30 x + 3 y = 10 y + x 29 x + 13 = 7 y = 7 (4x+2) 29 x + 13 = 28 x + 14 x = 1 then y = 4x+2 = 6 so 16
*September 21, 2014*

**physics**

1100.2 = 550 550 = (1/2) a t^2 550 = .5 * 1.2 * t^2 t = 30.3 seconds to go halfway (same for the second half) v = a t = 1.2 * 30.3 = 36.3 m/s 2 t = 60.6 seconds
*September 21, 2014*

**physics**

The vertical problem is the same for both Vi = 0 a = -9.8 until it stops Hi = 3.8 v = 0 + a t = -9.8 t h = 3.8 + 0 t - 4.9 t^2 when h = 0, the floor 4.9 t^2 = 3.8 t = .88 seconds in the air for both v at floor = -9.8 (.88) = - 8.62 m/s first ball straight down, x = 0 second ...
*September 21, 2014*

**Physics**

0 = 18 - 1.8 t t = 10 seconds to stop how far braking? d = av speed * time = 9*10 = 90 meters 125 - 90 = 35 meters before braking 35 meters / 18 meters/second = 1.94 seconds (best hurry)
*September 21, 2014*

**science**

P1 Vi = P2 V2 10(20) = P2(5) P2 = 40
*September 21, 2014*

**Physics**

surface area of sphere = 4 pi r^2 Watts/unit area at 15 m = 1.75/(4*pi*225)
*September 21, 2014*

**Physics**

d instructor = u t find t so you can find d, how far the instructor is from directly under when you drop. H = height H = (1/2) g t^2 t = sqrt (2 H/g) so d = u sqrt (2 H/g)
*September 21, 2014*

**chemistry**

125 (95-20)(4.184) Joules divide by 1000 to get kilojoules
*September 20, 2014*

**physics**

Calculate the total distance calculate the total time average v = distance/time
*September 20, 2014*

**Math (Proving of Inequalities)**

a^2-b^2 = (a+b)(a-b) (a+b) is + so if (a^2-b^2) is + then (a-b) must be +
*September 20, 2014*

**5th grade Math**

multiply (2/3) 3 = 2 cups (2/3) 1/2 = 1/3 t (2/3) 3/4 = 1/2 cup (2/3) 4 = 8/3 = 2 2/3 cup (2/3) 2 = 4/3 = 1 1/3 T
*September 20, 2014*

**PHYSICS**

G .35 Mb m/Ra^2 = G Mb m / Rb^2 .35 Mb/Mb = Ra^2/Rb^2 Ra/Rb = sqrt(.35)
*September 20, 2014*

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