Tuesday

September 30, 2014

September 30, 2014

Total # Posts: 18,717

**Calc**

Oh and by the way when x = 0 we have 0/1
*July 17, 2014*

**Calc**

df/dx = - x e^-x + e^-x = 0 for max or min within interval BUT you did not say the interval in general e^-x = x e^x 1 = x is one place where the slope is zero is the second derivative + or - ? d^2f/dx^2 = -x(-e^-x) -e^-x - e^-x = xe^-x -2 e^-x) = (1/e^x)(x-2) when x = 1 = (1/e...
*July 17, 2014*

**science**

force * time = change of momentum a) force = 49 * (6-0) / 3 = 98 N b) force acts on the average over one hundred meters c) work = force * distance = 98 * 100 = 9800 Joules interesting, lets see how much kinetic energy we have (1/2) m v^2 = .5 * 49 * 36 = 882 Joules s we are ...
*July 17, 2014*

**Math**

always multiply by one (top equal to bottom) so the units come out with the unwanted ones canceling 23 cm * (1 meter / 100 cm) note cm cancels top and bottom, left with meters besides we all know 23 cm = 0.23 meters :) b) NO !! 1000 mm / one meter = one 5 m * (1000 mm / 1 m...
*July 17, 2014*

**physics**

I bet they both hit the ground at the same time, whenever that is.
*July 17, 2014*

**where asre the = signs?Math**

I do not understand this.
*July 16, 2014*

**Alegbra**

subtract negative 40 from positive 119 or simply add 119 and 40 +119 - (-40) simplified = 119 + 40 = 159
*July 16, 2014*

**science**

Open the box and take the hard drive, or simply take the computer.
*July 16, 2014*

**American literature**

"...... community.(256)..... " What is your reference number 256 ?
*July 16, 2014*

**calculus**

Profit = Revenue - Cost P = -q^3 + 60 q^2 +(-1200+551)q - 760 dp/dq = -3 q^2 +120q - 649 zero for max or min q^2 - 40 q + 216.333... = 0 q = [ 40 +/-sqrt (1600-865)]/2 q = [40+/-27.1)/2 q = 34 or 6.5 to find out if max or min, take next derivative d^2p/dq^2 = -6q +120 at q = ...
*July 16, 2014*

**physics 2**

I do not understand. Mass of object increases above rest mass as speed of light is approached. .08 times original mass????
*July 16, 2014*

**physics**

energy to water per second = 1.86*10^8 Joules Kg water per second heated = m 1.86*10^8 = 4184 * m * 2
*July 16, 2014*

**US Government**

The answer is in the link Ms. Sue gave you.
*July 15, 2014*

**Alegbra**

It is very difficult to fit a line to one point.
*July 15, 2014*

**Alegbra**

both sides are 0 at (6,-8) then y goes down 5 times as fast as x goes up check: from that point go right 1 and down 5 (7, -13) is that on the line? -13 + 8 = ???? -5 (7-6) -5 = -5(1) sure enough
*July 15, 2014*

**Alegbra**

y = m x + b 7 = 0 + b b = 7 so y = -6 x + 7 where does that hit x axis ? 0 = -6 x + 7 x = 7/6 so (7/6 , 0) draw line through (7/6 , 0) and (0 , 7)
*July 15, 2014*

**Geometry**

2 pi r = 2 pi (2x) = 4 pi x
*July 15, 2014*

**Physics mit 2.01x**

No (former MIT professor), I do not do MITx problems in Course 8 or Course 2. You are on your own. The 8.01x crowd swamped this board the last time around.
*July 15, 2014*

**science**

pi r^2 h pi 1*1*12 = 12 pi cm^3 or cc = 37.7 cubic centimeters
*July 15, 2014*

**physics**

a) Huh? at x = 0 and t = 0 , y = 0 so the phase constant is 0 b) at x = .0229 m and t = .197 .745(.0229) - 42.9(.197) = -8.434 radians = -482 degrees which is -360 - 123 degrees
*July 15, 2014*

**physics**

well, first do the vertical problem, the ball how long does it take to fall 20 m? 20 = (1/2) (10) t^2 t^2 = 4 t = 2 seconds so it will take to seconds to fall. By symmetry it will also take 2 seconds to rise and hit the plane how fast is it going when it hits the ground? u = a...
*July 15, 2014*

**physics**

by the way part B is also the average speed times the time x = 5.25 * 5.2
*July 15, 2014*

**physics**

a = change in velocity / change in time = ( 0 - 10.5) / 5.2 m/s^2 x = (1/2) a t^2 = (1/2) * a from above * (5.2) * (5.2)
*July 15, 2014*

**SCI 207**

I suppose those are the people with expensive houses on the shore. However what is meant by "worst impacts"? If it means losing the most money it may be correct. However wealthy people probably can survive the loss of shore side property without ending up homeless. ...
*July 15, 2014*

**physics**

To go from km/h to m/s divide by 3.6 which is 1000 m/km / 3600 s/min a = change in velocity/time (note it is negative) F = m a By the way, this ignores wave resistance which would be a major part of the retarding force.
*July 15, 2014*

**chemistry**

P1 V1 = P2 V2 so V2 = P1 V1/P2 I am assuming that these are total pressures and no "gage" pressures. If they are gage pressures add 1 atm to both P1 and P2
*July 15, 2014*

**physics**

well, I guess it is ok to use g = 9.81 m/s^2 but we will have to check later if the thing is a significant fraction of an earth radius high. (1/2) m v^2 = m g h v^2 = 2 g h h = v^2/19.6 = 49*10^4 / 19.6 = 25,000 meters that is a small fraction of earth radius so constant g ...
*July 13, 2014*

**Physics**

Look below
*July 13, 2014*

**Physics**

If I have this picture right block one on the incline is pulling block two on the level above toward the incline. There is one force pulling block one down the incline and string tension T holding it back Fpull = 4.4 g sin 30 = 2.2 g 2.2 g - T = mu * 4.4 g cos 30 I assume that...
*July 13, 2014*

**Physics**

1 g/cm^3*1kg/1000 g* 100*100*100 cm^3/m^3 = 1000 kg/m^3 you know this anyway because the density of fresh water is about 1 g/cc or 1000kg/m^3
*July 13, 2014*

**Math 221**

well, if it ends in 0 or 5, divide by 5 26 / 21 that is 13*2/7*3 so there is nothing more to be cancelled.
*July 13, 2014*

**American Government**

This is not my field but one thought crosses my mind immediately. It is in the interest of each state to have as few welfare recipients as possible. Therefore each state would feel pressure to provide as little help as possible hoping that the people will decide to move to ...
*July 13, 2014*

**Science**

If you do A and the bread gets moldy with no air, then the mold spores probably did not come from the air.
*July 13, 2014*

**Science**

Graph that P V 8 1 4 2 2 4 1 8 Every time you cut the volume in half you double the pressure P V = k = 8 so P = 8/V so yes, confirmed
*July 13, 2014*

**math**

a bit over ten gallons a week at about three dollars per gallon = $30
*July 13, 2014*

**math**

out of every seven candies 5 are red and 2 are green so out of 5*7 = 35 candies 5*5 = 25 are red and 5*2 = 10 are green B.
*July 13, 2014*

**physics**

vertical problem (time and speed same as 104 meter fall): v = Vi - 9.81 t 0 = Vi - 9.81 t t = Vi/9.81 104 = (1/2) g t^2 104 = (1/2) (9.81)(Vi^2/9.81^2) Vi^ = 2 * 9.81 * 104 Vi = 45.2 m/s horizontal problem (constant speed) t = Vi/9.81 = 4.61 seconds u = 53/4.61 = 11.5 m/s tan...
*July 13, 2014*

**physic**

Because I believe that is the correct value for radius of the earth.
*July 13, 2014*

**physic**

for earth for example F = G M1 M2 /r^2 = (6.67*10^-11)(5.98*10^24)(67.5)/ (6.38*10^6 )^2 = 66.14 * 10^ 1 = 661 Newtons that better be pretty close to m g or 67.5*9.81 = 662 Newtons
*July 13, 2014*

**physic**

F = G M1 M2 / d^2 where G = 6.67*10-11 N m^2/kg^2 I think you mean radius for distance radius of earth = 6.38*10^6 meters
*July 13, 2014*

**Physics**

Hey look. I showed you how to do it for the earth mass and man mass. Do the same for the two balls .3 m apart. G * .3 *.3 / 3^2 = G
*July 13, 2014*

**Physics**

This is the same as your problem above with the different planets and the weight of the man on each.
*July 13, 2014*

**Physics**

same as problem above
*July 13, 2014*

**physic**

1609/4.740 and 1609/4.695
*July 13, 2014*

**physic**

x = 6 t + (1/2)(2) t^2 = 6(8) + 64 = 112 meters
*July 13, 2014*

**history**

import duties ?
*July 13, 2014*

**Math**

total area of patio = 240 area of garden = x^2 useable patio area = 12 - x^2 if x is more than 12, you can not walk around the garden
*July 13, 2014*

**physics**

better get a CD and try it :)
*July 12, 2014*

**physics**

ok, well if I have it right the pin is at the edge of the hole, 0.75 cm above the center of gravity of the CD for a small angle A the restoring moment about that pin is -m g (.0075)sin A = -.0075 m g A = -.0075*.017*9.81 A = -.00125 A the moment of inertia of the CD about its ...
*July 12, 2014*

**physics**

sorry, I need a picture.
*July 12, 2014*

**physics**

By the way magnetic field lines usually are draw going from N to S OUTSIDE the magnet.
*July 12, 2014*

**physics**

1. How would they cross? 2. different constants/r^2 k Q1 Q2/r^2 versus G M1 M2/r^2 see https://www.google.com/search?q=exponential+field+definition&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb#channel=sb&q=exponential+function+definition&...
*July 12, 2014*

**whoops**

14.4 *10^-9 = 1.44 *10^-8
*July 12, 2014*

**physics**

k Q/r 9*10^9 * 1.6*10^-19/10^-1 14.4 *10^-9 = 1.44 *10^-10
*July 12, 2014*

**algebraic expression**

I don't know.
*July 12, 2014*

**physics**

yes, looking for ratio of charge to mass, knowing mass, could calculate charge (slight oversimplification) see: http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Ryan_McAllister/Slide3.htm
*July 12, 2014*

**physics**

potential energy of mass m at surface = -GMmoon m/r = - m (6.67*10^-11) (7.35*10^22) /(1.74*10^6) = m (28.2*10^5) Needs that many Joules of Ke so (1/2) m v^2 = 2.82*10^6 m v^2 = 5.64 *10^6 v = 2.37*10^3 = 2370 m/s by the way: http://www.1728.org/escvel.htm
*July 12, 2014*

**physics**

You are welcome.
*July 12, 2014*

**physics**

E = 9*10^9 Q/r^2 here Q = 1.6*10^-19 so 9*10^-3 = 9*10^9 (1.6*10^-19)/r^2 r^2 = 1.6 * 10^-7 = 16 * 10^-8 r = 4*10^-4 meters = .4 millimeters
*July 12, 2014*

**Math**

using that regression line calculator y = -4.29x + 28.3 (2.5, 17.6)
*July 12, 2014*

**Math**

http://www.alcula.com/calculators/statistics/linear-regression/
*July 12, 2014*

**Math**

same as above. enough already.
*July 12, 2014*

**Math**

It would take you less time to do these problems than to post them.
*July 12, 2014*

**Math**

Your problems are all answered by the link I gave you.
*July 12, 2014*

**Math**

tan(90-39) = AP/40 so AP = 49.4 tan (90-52) = BQ/40 so BQ = 31.2 so P is (49.4-31.2) or 18.1 km south of Q and 40 km west of q tan theta = 40/18.1 theta = 65.7 degrees east of north from P to Q
*July 12, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*July 12, 2014*

**Math**

The link I gave you does all of these. In fact if you have a normal table handy, all your questions are really answered in it.
*July 12, 2014*

**Math**

Use link below for normal curve: http://davidmlane.com/hyperstat/z_table.html
*July 12, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*July 12, 2014*

**Math**

122 z = (122-182)/30 = -2 242 z = (242 - 182)/30 = +2 then use normal table or use: for example http://davidmlane.com/hyperstat/z_table.html result .9545 in that range so .9545*600 = 573
*July 12, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*July 12, 2014*

**Dynamics**

d^2x/dt^2 = 2 t - 1 dx/dt = t^2 - t + c at t = 0, dx/dt = 2 so c = 2 so v = dx/dt = t^2 - t + 2 x = (1/3) t^3 - (1/2) t^2 + 2 t + c when t = 0 x = a so c = 1 x = (1/3) t^3 - (1/2) t^2 + 2 t + 1 so at t = 6 v = 36 -6 + 2 = 32 m/s and x = 67 total distance = 67-1 = 66 assuming x...
*July 12, 2014*

**Hunting training**

So would I (but I know nothing about this really)
*July 12, 2014*

**Hunting training**

I agree because my spaniel won't hunt.
*July 12, 2014*

**PHYSICS**

at ten meters it has dropped 15 meters (1/2) m v^2 = m g h v^2 = 2 * 9.81 * 15 = 294.3 v = 17.2 m/s at 10 m above ground d = (1/2) g t^2 25 = 4.9 t^2 t = 2.26 seconds
*July 12, 2014*

**science**

walk north until the arrow flips :)
*July 12, 2014*

**science**

...... but not found yet
*July 12, 2014*

**science**

The magnetic monopole is a much sought after object :)
*July 12, 2014*

**science**

http://cosmoquest.org/forum/showthread.php?91956-The-Moon-Specular-and-Diffuse-Reflection
*July 12, 2014*

**science**

It is called reverberation. See: http://www.wisegeek.com/what-is-a-reverberation.htm#didyouknowout
*July 12, 2014*

**Math**

You are welcome.
*July 12, 2014*

**Math**

to fit in the box the radius of a round pizza must be less than or equal to 6 inches A = 3.14159 * r^2 = 3.14159 * 36
*July 12, 2014*

**PHYSICS**

F * 100 / 80 = 200
*July 12, 2014*

**chemistry step by step for me clearly**

sorry 3 * 6 = 18 mols
*July 12, 2014*

**chemistry step by step for me clearly**

I have to assume you mean 2.684 grams of Al2(SO4)3 and water per cc. One of those grams is water so we have 1.684 grams of Al2(SO4)3 in every cc Al2(s04)3 How many grams per mol? 2 Al = 2 * 27 = 54 3 S = 3 * 32 = 12 O = 12 * 16 = 192 so Al2 (SO3)4 = 278 grams/mol If we have 1....
*July 12, 2014*

**Physics**

How fast can the stack accelerate without the books above the first one slipping? weight down on bottom book = 5 * 4 kg * g maximum static friction force between top 5 and bottom book = 5 * 4 * g * 0.3 so max force = mass of top 5 * a 5*4*g*.3 = 5*4 * a so a = .3 g that gives ...
*July 11, 2014*

**electric circuit**

Interesting, went nameless :)
*July 11, 2014*

**Trigonometry**

A(of L and w) = L * w if w = 1 then A(L) = L
*July 10, 2014*

**stats**

57.21% or .5721
*July 10, 2014*

**stats**

I think the same as the probability that one is more than 2.90 mean = 3 we are at .1 below mean Z = -.1/.55 = -.18 from normal table if Z = -.18 then F(z) about .421 so about 42% are below so about 58 % are above 2.9 For accurate table use http://davidmlane.com/hyperstat/...
*July 10, 2014*

**error**

arithmetic! (10*9*8)/(16*15*14) = .2143 1 - .2143 = .7857
*July 10, 2014*

**Math**

p = probability defective = 6/16 = .375 1 - p = 10/16 = .625 = probability good we do three trials on the box. They all must be good if it is to pass probability of first trial fuse good = 10/16 probability of second choice being good fuse = 9/15 third = 8/14 so probability of...
*July 10, 2014*

**No picture**

If you tried to copy and paste, that does not work here.
*July 10, 2014*

**US Government**

However in real life they seem to be closer to: http://www.constitutionparty.com/our-principles/key-issues/
*July 10, 2014*

**US Government**

http://www.modernwhig.org/handbook/who-are-modern-whigs/what-we-believe I suspect Republicans like to think they share these principles.
*July 10, 2014*

**PHI 208 Week 4 Reading Quiz**

Hard to tell.
*July 10, 2014*

**Physics**

F = q E = m a so a = (q/m)E = (1.6*10^-19/1.67*10^-27)5*10^2 = 4.79 * 10^10 m/s^2 v = a t 3.5*10^4 = 4.79 * 10^10 t t = .731 * 10^-6 = 7.31*10^-7 seconds d = (1/2) a t^2 Ke = (1/2) m v^2 I think you can do c and d
*July 10, 2014*

**US Government**

http://www.fec.gov/ans/answers_pac.shtml
*July 10, 2014*

**physics**

There is indeed a magnetic dipole which has field lines of the same shape as an electric charge dipole. We also use the dipole model in fluid physics combining a source and a sink close together which also has the same sort of streamlines. All are examples of moments, meaning ...
*July 10, 2014*

**math**

Here is a picture of a similar (no pun intended) problem http://mathforum.org/sanders/connectinggeometry/ch_09Similar.html
*July 10, 2014*

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