Thursday

October 23, 2014

October 23, 2014

Total # Posts: 19,012

**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*

**physics**

well in this case the result is exact, but in general there could be a constant of proportionality between the output and the input that we could not get from dimensional analysis for example Force on a plate of area A in a fluid of density rho in kg/meter^3 and speed v in L/T...
*September 20, 2014*

**physics**

R = v A (look at a drawing of what you have here) now the way you are supposed to do it v = L/T A = L^2 R = L^3/T = (L/T)L^2 so R = L A/T but L/T = v so R = v A
*September 20, 2014*

**chemistry**

2 mol of water --> 2*18 g 1 mol O2 --2*16 g (2*18/2*16) * 7.4 mg = 9*7.4/8 = 8.325 mg 7400 grams O2 ---> 8325 grams H2O ---> 8325 mL H2O or 8.325 liters
*September 20, 2014*

**HELP IN SCIENCE ASAP!!**

yes, yes
*September 20, 2014*

**Science**

You mean 10 m/s^2 I assume wow, 1 g for five minutes ? to the moon ? anyway 5 min = 300 s v = Vi + a t v = 0 + 10 (300) = 3000 meters/second
*September 20, 2014*

**Science**

yes, yes
*September 20, 2014*

**Pre-Cal**

y = +/- sqrt(1-x^2) if y is to be real, x must be x^2 </= 1 -1 < x < +1 similarly y ranges from -1 to + 1 so our function 2 x - 5y is maximum when x is 1 and y is -1 2 + 5 = 7
*September 20, 2014*

**math**

G = 1000 + 325 m E = 2500 + 325 m E always pays more than George by 1500
*September 20, 2014*

**Algebra 2**

1 and 2 fine 3. Evaluate (2.0 x 10^-7)/(8.0 x 10^-9). Write the answer in scientific notation. A: 0.25 x 10^2 but usually written 2.5 * 10^1 age is not a function of last name R = 75 - 3.5 d if d = 5 R = 75 - 17.5 = 57.5 dollars left in pocket
*September 20, 2014*

**Physics**

p Newton = m v p relativistic = m v /sqrt(1 = .75^2) so 100(p relativistic - p newton)/p rel here 1/sqrt(1-.75^2) = 1.512 so 100 ( 1.512 - 1)/1.512 = 33.9 %
*September 20, 2014*

**Physics**

E = m c^2 so m = E/c^2 E = 2*10^9 *21 * 7 *24 *3600 = 2.54*10^16 c = 3*10^8 m/s c^2 = 9 * 10^16 so m = 2.54 / 9 = .282 Kg = 282 grams
*September 20, 2014*

**physics**

You need to know two things: 1. how long does it take to fall 0.7 m 2. How fast is your horizontal velocity after falling 2.76 meters? Then distance = horizontal velocity * time to fall 0.7 meters = u t -------------------------- so, how long to fall 0.7 m? 0.7 = (1/2) g t^2 t...
*September 20, 2014*

**History**

French traders used the Red River to ship to New Orleans from the southern part of Oklahoma. I think they probably mean Red River although indeed the French fur traders also used the Arkansas.
*September 19, 2014*

**History**

None of the others happened in or around 1821 so I would say A
*September 19, 2014*

**physics**

original south = 9.75 cos 25 final south = 8.64 sin 35 original east = 9.75 sin 25 final east = -8.64 cos 35 south a component = (final south -original south)/ .179 east a component = (final east component - original east component) / .179 resultant mag of a = sqrt (south a^2...
*September 19, 2014*

**Math**

x axis intercepts at y = 0 (x-3)(x+1) = 0 x = 3 and x = -1 y axis intercepts where x = 0 y = -3
*September 19, 2014*

**physics**

Vi = 60.32 yes u = 85.3 cos 45 = 60.32 also but forever v = Vi + a t = 60.32 -9.81 t so at top when v = 0 t = 6.15 seconds coasting up h at top = Hi + Vi t -4.9 t^2 = 587 + 60.32 (6.15) - 4.9(6.15^2) = 773 meters high at 6.15 seconds when fall starts now it falls 773 = 4.9 t^2...
*September 19, 2014*

**algebra - check my answer?**

yes
*September 19, 2014*

**Math**

4(x-1)^2 + 3 (x-1) - 3 4(x^2-2x+1) + 3 x - 3 - 3 etc
*September 19, 2014*

**Math**

Yes, what Mia said :)
*September 19, 2014*

**Math**

about x axis? for any x is are there equal in magnitude + and - values of y? y ^2 = x+1 y = +/- sqrt (x+1) so yes but x must be >-1 about y axis? Nah, this is a parabola opening to the right with as vertex at (-1 , 0)
*September 19, 2014*

**Math**

Everything on the number line left of x = -2 including x = -2 so Big black dot on -2 arrow pointing left from there. I do not know what the number six has to do with the problem. B is the only one with all the values in our domain.
*September 19, 2014*

**Math**

w +(w+6) = 34 2 w + 6 = 34 2 w = 28 w = 14 ================== 5 a - 20 - 8 a = 55 -3 a = 75 a = 25 ====================== 6 n - 7 = 45 6 n = 52 n = 26/3 as you wrote it If you mean instead (2n-7)/3 = 15 then 2 n - 7 = 45 2 n = 52 n = 26
*September 19, 2014*

**english**

Illustrator
*September 19, 2014*

**Math**

You are welcome.
*September 19, 2014*

**Math**

n - 6 >/= 2 n >/= 8 agree
*September 19, 2014*

**French**

Everyone always says they are fine even if on the verge of death.
*September 19, 2014*

**History**

agree B turned out to be major.
*September 19, 2014*

**Math**

g / - 5 < -18 if you multiply both sides by -5 you must reverse the direction of the arrow. g > + 90 C.
*September 19, 2014*

**History**

Negotiated relatively safe traffic through Indian lands from Missouri west
*September 19, 2014*

**whoops, -1 not + 1 use Steve's answerr**

dumb error
*September 19, 2014*

**Pre-Calculus Questions**

slope = (-3 - 3)/ (1+5) = -6/6 = -1 y = -x + b 3 = -1(-5) + b b = -2 y = -x - 2 =============================== x axis(0, -3) y axis where y = 0 x^2 - 2 x - 3 = 0 (x-3)(x+1) = 0 x = 3 or x = 1 so axis of symmetry and vertex at x = (1+3)/2 = 2 then y vertex = 4-4 - 3 = -3 so ...
*September 19, 2014*

**History**

Spanish gave up claim to Oregon territory
*September 19, 2014*

**physics**

v = 20 - 9.8 t v = 0 at top 9.8 t = 20 h = 20 t - 4.9 t^2 or m g h = (1/2) m v^2 h = (1/2)v^2/g
*September 19, 2014*

**Mathematics**

(1/2) 116 = 58 (1/2) 8 = 4 tan 58 = 4/h
*September 19, 2014*

**math algebra word problems**

Their speed is 1.5 + 1.2 = 2.7 miles a day
*September 19, 2014*

**physics**

period = 1/ frequency wavelength = period * speed so wavelength = speed / frequency Your textbook must have that !!!
*September 18, 2014*

**Algebra**

2 m^2 + 3 = m 2 m^2 - m + 3 = 0 m = [ 1 +/- sqrt (1 - 24) ]/ 4 = [ 1 +/- sqrt(-23) ]/4 complex conjugate pair.
*September 18, 2014*

**science**

....and you answered the question about how many cars and trucks incorrectly thereby confusing some other poor student.
*September 18, 2014*

**science**

Moreover we do not have the slightest idea what microscopes you might have in your school.
*September 18, 2014*

**physics**

lambda = distance = speed * time Time = period = 1/ frequency
*September 18, 2014*

**Physics**

a = change in velocity/change in time = (14 -0) / 10 2.) zero 3.) (1/2) m v^2 = m g h so v = sqrt (2 g h)
*September 18, 2014*

**Math**

If there were 6 trucks there would be 30 cars and 36 total, no good t + 5 t = 30 6 t = 30 t = 5 not 6
*September 18, 2014*

**math**

no x^n = x * x * x * x .......... n times
*September 18, 2014*

**Math**

balance = 4000 (1.05)^n geometric sequence a = 4000, r = 1.05 4000 4200 4410 etc
*September 18, 2014*

**MATH WORD PROBLEM**

180 = (3/2)x x = 360/3 = 120
*September 18, 2014*

**physics**

a = change in velocity / change in time and F = change in momentum / change in time (Newton #2, F = d/dt (m v) = m a if m is constant)
*September 18, 2014*

**physics**

a = (0-12)/.1 F * t = change in m v F * 0.1 = 60 (0-12)
*September 18, 2014*

**Urgent Spanish Check**

Well, for a bunch of Norte Americanos we are not doing too badly.
*September 17, 2014*

**Urgent Spanish Check**

hmmm, una clase is feminine but lo is masculine. La is feminine.
*September 17, 2014*

**social studies check**

I do not think he accomplished what he was hoping to accomplish. What he did accomplish was not his original objectives.
*September 17, 2014*

**social studies check**

Well, he did not find China. He ended up dead someplace west of the Mississippi. He did get a lot done and was the first European explorer in those parts, however the goals of his sponsors to find vast riches of gold, jewels and silver and find a route to the Orient were not ...
*September 17, 2014*

**social studies check**

I agree with D. It is hard to sustain a culture when everyone is dead.
*September 17, 2014*

**Urgent Spanish Check**

You are welcome.
*September 17, 2014*

**Urgent Spanish Check**

EL examen VERDE miS hermanas LOs
*September 17, 2014*

**social studies check**

I think the key word is PERMANENT. The woodland people were still in place when the Europeans arrived.
*September 17, 2014*

**social studies check**

THey did NOT want to form large plantations as in South Carolina !!
*September 17, 2014*

**physics**

Give ALL the units of resistivity. Then the problem solves itself as long as you know Area of circle = pi d^2/4 Resistance = resistivity * length/area
*September 17, 2014*

**English**

The only problem I have with these sentences is that they are extremely awkward. I would have said: I think I will be a good bow rower because I can balance the boat accurately. I think I will be good rowing in the middle of the boat because I am strong and can make the boat ...
*September 17, 2014*

**Physics please help**

slope of displacement versus time or dx/dt at any point is velocity v = integral of a dt if you were given the ACCELERATION ,a, you would need to do area, but you were not.
*September 16, 2014*

**math**

x y z 4 y z y>z 4 + y + z = 6 y + z = 2 since y>z y = 2 and z = 0 4 2 0
*September 16, 2014*

**Pre-Calculus**

a) so use -3 for x (-3)^2 + 9 = 9+9 = 18 b) now use -2 for x (-2)^2 + 9 = 4 + 9 = 13
*September 16, 2014*

**Calculus I**

dL = a Lo dT L = a Lo T + constant when T = 0, L = Lo so L = (a Lo) T + Lo To is y (or in this case L)axis intercept (a Lo) is slope
*September 16, 2014*

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