Friday

August 1, 2014

August 1, 2014

Total # Posts: 17,591

**Physics waves- check answers please**

You are welcome.

**Physics waves- check answers please**

I agree on all but #3. If by loop they mean antinode they occur 6 times including the ends. The distance from a node to an antinode is 1/4 lambda. I see ten quarter wavelengths in the 24 feet so 10( lambda/4) = 24 lambda = 2.4 *4 = 9.6 meters

**physics**

Generally yes, when you cook something the temperature goes up, storing heat that can be released later when the fire goes out.

**Social Studies**

I should have said between Iraq, Turkey, Syria, and Iran.

**Social Studies**

When the Middle East was split up into "mandates" under European countries after the Ottoman Empire was demolished, little attention was given to the ethnic or historical backgrounds of the various groups of people. Lines were arbitrarily drawn and this was called &q...

**Social Studies**

Once again - C

**Dynamics**

at top of loop centripetal acceleration = g or it leaves the track g = v^2/a height at top of loop = 2 a potential energy at top of loop = m g h = 2 m g a total energy at top of loop = .5 m v^2 + 2 m g a = .5 m g a + 2 m g a = 2.5 m g a so h = 2.5 a

**math**

for combinations: n!/[r!(n-r)!] 6! /[ 3! (6-3)! ] 6*5*4/ (3*2*1)

**SPAM**

Some of these are virtually identical and some are terribly easy. Try them before posting.

**Chemistry**

OOps sorry, thinking atomic number :(

**Chemistry**

1.2 * 5 grams/ liter = 6 grams/liter Na = 11 g/mol Cl = 35.5 g/mol Na Cl = 46.5 g/mol 6/46.5 = .129 M

**statiatics**

.4686 http://davidmlane.com/hyperstat/z_table.html

**physics**

60,000 m/3600 s = 16.7 m/s 80,000 m/3600 s = 22.2 m/s (16.7 - 22.2)m/s / 5 s = -1.11 m/s^2

**Physics**

I am not sure I have ever seen a really watertight shipping container but anyway:) Volume of container = 6*2.2*2.3 = 30.36 m^3 Buoyancy of container = 30.36*1025 g N = 31,119 g N Buoyancy of lift bag = 1025 g (4/3) pi r^3 = 21,094 g N total up force = 52,213 g N total down for...

**Physics**

d bus = .5 a t^2 = .25 t^2 d student = d bus + 10 = 3 t so .25 t^2 = 3 t - 10 .25 t^2 -3 t + 10 = 0 t^2 - 12 t + 40 = 0 t = [ 12 +/- sqrt(144 -160) ] /2 oh my, complex t student only catches bus in imagination

**Physics**

22,000/3600 = 6.11 m/s 85 000/3600 = 23.61 m/s average speed during acceleration = 14.86 m/s t = distance/speed = 200/14.86 = 13.46 s a = speed change/time = 17.5/13.46 = 1.3 m/s^2

**Calculus Help**

b) the answer is in (a) twice 2178 feet I think you can figure the rest out

**Calculus Help**

90 mi/hr = 132 ft/s (a) first how long and how far to reach 132 ft/s v = 0 + 4 t 132 = 4 t t = 33 s to reach 132 d = .5 a t^2 = 2 (33)^2 = 2178 ft to reach cruising speed 15*60 = 900 seconds total 900 - 33 = 867 seconds left how far at cruising speed 132 ft/s * 867 s = 114,444...

**calculus help**

Nothing. I use SCI unless ordered otherwise :)

**calculus help**

4.14 m/s^2 = 13.6 ft/s^2 :)

**calculus help**

22 mph = 9.83 m/s 50 mph = 22.35 m/s a = change in velocity/time = (22.35 -9.81)/3 = 4.18 m/s^2 or about half g

**math**

a) y = 1 x - 3 slope = m = 1 slope of perpendicular = -1/m = -1/1 = -1 so y = -x + b 2 = -3 + b b = 5 so y = -x + 5 do the other the same way

**SkatingDJ**

It must be numbered 0 to 5. Never heard of that before. odd = 1 3 5 even = 0 2 4 prob of odd = 1/2 colors = 2 y + 1 b + 1 g so prob y = 2/4 = 1/2 the two events are independent so p = (1/2)(1/2) = 1/4

**math**

r^2 = k V k = r^2/V if you multiply r by 9, then V by 81 k = (9r)^2/81V = r^2/V so e

**Physics**

LOL - are you sure all the charges are the same Stephanie ?

**physics**

You are welcome :)

**physics**

half the area is twice the speed V1 = 1 m/s V2 = 2 m/s Bernoulli (1/2) rho V1^2+P1 = (1/2) rho V2^2+P2 rho water =1000 kg/m^3 2921 Pa is very low by the way, like 1 atm = 100,000 Pa for example. Perhaps they mean gage pressure. 500 (1)^2 + 2921 = 500 (2)^2 + P2 2921 - P2 = 150...

**Math**

Part A: How many oxygen atoms are there in 50 atoms? ======================= Huh ? perhaps you mean in 50 molecules? I will assume that 1/4 * 24 = 6 Oxygen atoms / molecule 6*50 = 300 in 50 of them If there are 6 in one then there are 300 in 50

**math**

6770 *60/6.4 = 63,470 feet/minute By the way those of us who work at sea figure about 5 seconds per nautical mile. Some lighthouses flash at the same time as they sound a horn. If you hear the horn five seconds after you see the flash, you are a mile away from the lighthouse.

**Physics**

F = m a CONSTANT acceleration requires constant force.

**Linear programming**

x = days at Loc 1 y = days at Loc 2 then limits and intecepts deluxe 10x+20y >/= 2000 (0,100)(200,0) better 20x+50y >/= 4200 (0,84)(210,0) standard 13x+6y >/= 1200 (0,200)(92.3,0) graph those and cost constraint c = 500 x + 800 y Now test upper corners try (0,200) all...

**mathematics**

see if this helps: http://davidmlane.com/hyperstat/z_table.html

**Calculus Help Please Urgent!!!**

square side = x triangle side = y perimeter = 4 x + 3 y = 14 area = x^2 + sqrt3 (y^2)/4 x = (14 - 3 y)/4 area = (196 - 84 y +9y^2)/16 + 4 (3^.5)y^2/16 = [1/16] (196 - 84 y + 15.93 y^2) dA/dy = 0 for max or min 0= -84 y + 31.86 y^2 so y = 0 or y = 2.63 so x = 14/4 or 1.528 so 4...

**Math**

I have no idea. It depends on the pressure in the ball and the temperature. P V = n R T so n = moles of He = P V/ (RT) = P (4/3)r^3 /(RT) a mol of He has mass of 4 grams

**Math**

tan^-1 (.25) = 14 deg

**Math**

You can not copy and paste so I do not see your choices but tan E = 20/d d = 20/tan E

**MATH FACTOR POLYNOMIALS**

I was looking for what with 3 would make 2 and it is one.

**MATH FACTOR POLYNOMIALS**

+3-1 = +2 so (x+3)(x-1)

**Applied mathematics**

14/8 apple 11/8 orange 9/8 cranberry = 34/8 = 4 1/4

**math**

Go ahead, try to make a tile floor out of regular pentagon tiles

**Social Studies**

I would say C The British should have split the Kurds off after WW 1 since they really do not belong with the Iraqis or the Turks.

**Physics**

2 cars pulling together on level surface? Mass of cars = 3800 kg weight of cars = 3800*9.81 = 37278 N so max friction force of tires = 37,278 N mass of full vault =38803 kg weight of full vault = 380,657 N max retarding friction = .57*380657 = 216,974 N In other words, based o...

**History HELP! ASAP**

Each of your questions requires an essay to help you and perhaps if you try to write them someone here can help with them. In this case I might concentrate on the interaction of England, France, US colonies and Iroquois and Algonquins. In the other question I would discuss rea...

**science**

m g h = Potential energy at top = 822 60 (9.81) h = 822 h = 1.4 meters

**calculus help**

https://www.wolframalpha.com/input/?i=derivative+of+x^2%28x%2B3%29%2F%28x%2B1%29^3 6x / (x+1)^4

**calculus help**

then do it again :)

**calculus help**

[(x+1)^2 (3 x^2)-x^3 (2)(x+1)] /(x+1)^4 [(x+1)(3x^2) - 2 x^3 ]/ (x+1)^3 [ 3 x^3 + 3 x^2 -2 x^3 ] / (x+1)^3 [ x^3 + 3 x^2] /(x+1)^3 x^2 (x+3) / (x+1)^3

**calculus help**

https://www.wolframalpha.com/input/?i=derivative+of+%28x^3%29%2F%28%28x%2B1%29^2%29+

**Math**

how many cups in a gallon? 16 so 2 cups concentrate + 16 cups water = 18 cups lemonade so concentrate / lemonade = 2/18 = 1/9 now how many ounces in a pint (a pint is a pound the world around :) 16 so 1/9 =x/16 x = 16/9 = 1.78 oz

**SS**

Build factories, farms, houses providing residents with jobs.

**calculus help**

Play with this: https://www.wolframalpha.com/input/?i=derivative+of+1%2B%281%2Fx%29%2B%285%2Fx^2%29%2B%281%2Fx^3%29+

**Optics - sorry, not I **

sorry, optics is not my thing at all :(

**calculus help check and help**

a) calculate lim t->infinity (v. answer: mg/c ----->what is the meaning of this limit ============================== It is the "terminal velocity" (Google that) which is the speed where the drag force equals the weight. One uses a parachute so that one's te...

**physics**

a = change in velocity/time = (0 - 43)/.28 = - 154 m/s^2

**Geometry**

for similar figures areas scale with the square of lengths so sqrt(4/49) = 2/7

**math**

1.025^10 = 1.280084544 * 5000 = 6400.42

**calculus**

http://www.mathsisfun.com/data/function-grapher.php f' = 7 e^7x - e^-x when is that zero? 7 e^7x = e^-x 7 e^8x = 1 e^8x = 1/7 8 x = ln(1/7) x = -.243 at min

**calculus help**

try : https://www.google.com/search?q=graph+ln%28x%29+from+1+to+6&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a&channel=sb ln 6 = 1.79 ln 1 = 0 ln 6 - ln 1 = 1.79 1.79/5 = .36 approx ln x = .36 e^ln x = ? = e^.36 so x = 1.43 sure enough between 1 and 6 :)

**Algebra**

2 (a+1) / [(a+1)(a-1)] for starters :)

**Geometry- trig ratio**

sin 55 = 21,000/hypotenuse we want that hypotenuse

**science**

you want traction, not slipping, so increase friction.

**Math**

sin 10 = PR/16 PR = 16 sin 10

**Algebra**

You are welcome. You could have done this by long division but often you can see the factors more quickly.

**Algebra**

2 x^3 – x^2 – 24 x + 12) = (2 x^3 -24 x) - (x^2 - 12) = 2 x (x^2-12) - 1 (x^2-12) = (2x-1)(x^2-12) now divide that by (2x-1) :)

**Math**

sin 10 = PR/16 PR = 16 sin 10

**Math**

1.05^2 - 1 = 10.25 APY Wilder 1.0081666^12 - 1 = 10.2524 APY Cheapskate so go with cheapskate ten years 1.05^20 =2.6532 *85,000 = 225,530.30 1.0008166667^120 = 2.65387 *85,000 = 225,579.18 Cheapskate is 48.88 better

**english**

The magnificent king emerged victorious eliciting a groan from his opponent who had been deserted by his muses depriving him of the strength of his convictions :-)>

**Geometry - Area**

You are welcome :)

**Geometry - Area**

find the area of each of the 6 equilateral triangles making up the hexagon Each side of triangle = 12 yards { by the way, first check apothem length because it is our altitude ) tan 30 = (1/2)(12)/apothem apothem = 6/tan 30 = 10.4 - sure enough, whew } so area of triangle = (1...

**math**

5 * .011 * p = 82.5

**math**

10 * .025 * 5000 5000 + part A (ignoring inflation :)

**chemistry**

Use google for conversion 1500 mm Hg = 1.97368421 atm = 199 983.553 pascals

**Algebra II**

In other words you did one of 120 sequences that yield 7 successes out of 10 trials.

**Algebra II**

....but the probability of failure is not independent of the probability of success :)

**Algebra II**

binomial distribution p(sucess) = 12/15 = 4/5 = .8 1-p = 1/5 = .2 n = 10 k = 7 P(x=7) = C(10,7) * .8^7 * .2^3 C(10,7) = 10!/[ 7! (3!) ] = 10*9*8 / (3*2) = 80*9/6 = 120 so P = (120)(.8^7)(.2^3) = 0.201

**geometry**

100 = 4x^2 25 = x^2 x = 5 or -5 but if you really want to use formula x^2 + 0 x - 25 = 0 x = [ -0 +/- sqrt (0 + 100) ] / 2 x = +/- 10/2 x = +/- 5

**math (matrix)**

I assume you meant the determinant 24 x + 3 x^2 + 6 x + 10 - 9x = 25 3 x^2 + 21 x -15 = 0 x^2 + 7 x - 5 = 0 x =-7/2 +/- (1/2) sqrt(69) What a mess, assume you have a typo. To invert matrix use http://matrix.reshish.com/inverse.php

**math**

100 * (1/8)/ (8/12+3/12) = 100 * (1/8) / (11/12) = 100 * (3/24)(22/24) = 100 (3/22) = 13.6%

**Calc III**

not a valid transformation, zeros on diagonal check with http://www.wolframalpha.com/widgets/view.jsp?id=d6a52679e750c30e320a7094ec975598

**math**

pi D = 3.14159 * 13

**math**

1" = 50 miles IS 2" = 100 miles so if 2" is only 25 miles, we will need four times as long a sheet of paper. so 4

**whoops, arithmetic error**

t^2 - 2 t - 3 = -(1/5)(h) t^2 - 2 t = -h/5 + 3 t^2 - 2 t + 1 = -h/5 + 4 (t-1)^2 = -(1/5) (h - 20) so max height at one second of 20 meters

**Math 10**

that is a parabola (quadratic) 5 t^2 - 10 t - 15 = -h find the vertex by completing the square t^2 - 2 t - 7.5 = -(1/5)(h) t^2 - 2 t = -h/5 + 7.5 t^2 - 2 t + 1 = -h/5 + 8.5 (t-1)^2 = -(1/5) (h - 42.5) so max height at one second of 42.5 meters

**math**

r = 24 in /gift * 1 yd / 36 in * number of gifts r = (24/36) * number of gifts cost = 2 * r

**math**

10 apples/basket 2 baskets/bushel so 20 apples per bushel min 900/20 = 90/2 = 45

**math**

number of cuts = (n-1) amount wasted = 1/16 * (n-1) amount total = (3/32) n + (1/16) n - 1/16 so 25 16/32 = 5 n/32 -2/32 816/32 +2/32 = 5 n/32 818 = 5 n n = 163.6 so 163

**free-body diagram help**

You only need the horizontal forces in this case because the friction force(not the coefficient) is given. 45 - 13 = 20 a work done = change in kinetic energy = (45 - 13) (4) Newton meters or Joules

**Physics**

weight of ladder = m g = W force down on floor = W max friction force = .3 W so horizontal force on top of ladder from wall = . W Take moments about base of ladder .3 W (L sin T) = W(L/2)cos T .3 sin T = (1/2) cos T tan T = .5/.3 T = 59 degrees Notice that the ladder length do...

**maths**

1.875 km * 2 * 6 = 22.5 km

**Maths**

3 a = 4 2 a = -3 there is only one variable here, a there is no intersection of lines so no solution by elimination or substitution: a = 4/3 for the first equation a = -3/2 for the second equation

**Math**

Very interesting but as far as I know these are your apparel dimensions. I do not read minds and have no idea what you are looking at. Is it a triangle maybe?

**math PLEASE HELP!!!!!**

girth = 2(32+49) = 162 times length 41 = 6642 ft^2 base area = 32*41 = 1312 times height = 64288 ft^3 Why on earth do you need a formula? Draw a picture.

**Circle Geometry**

draw a picture line from center of circle to tack hits circumference at a right angle (because it is a radius) and therefore that is the closest point to the tack. also line from circle center to ground is 90 deg so right triangle d is hypotenuse center to tack r^2 + 58^2 = d^...

**Calculus Help Please!!!**

Q = Qi e^-k t when Q/Qi = 1/2 .5 = e^-k t ln .5 = - 4 k so k = (ln .5) / -4 Q = 800 e^ (ln .5)t / 4 k = .1733 so Q = 800 e^-.1733 t if t = 30 Q = 800 e^-5.2 Q = 4.4 mg 1/800 = e^-.1733 t ln(1/800) = -.1733 t 38.6 days enough already

**Physics multiple choice questions**

Ah, first you try and it is too late because I have to go to sailing practice. Maybe Steve will help.

**Calculus Help Please**

ln x y = lnx + ln y ln x + ln y -cos^-1(x-1) = x 1/x + (1/y) dy/dx+(1/[1-(x-1)^2])^.5 = 1 1/x +(1/y)dy/dx+(1/(-x^2+2x)^.5) = 1 (1/y) dy/dx = 1 - 1/x - [1/(x(2-x))^.5 dy/dx = y { 1 - 1/x - [1/(x(2-x))^.5 } when x = 1 ln x + ln y -cos^-1(x-1) = x 0 + ln y - pi/2 = 1 ln y = 1 + p...

**Physics**

east is + 1500 * 25 - 2000 * 0 = 3500 v

**Physics**

change in momentum of car A = 1250 (40) = 50,000 toward the west so change in momentum of car B is 50,000 toward the east 50,000 = 2000 (east velocity - -25) 25 = east velocity + 25 east velocity = 0 stopped it dead in the water :)

**physics**

change in temp = 90 - 15 = 75 deg C heat in = mass * specific heat * change in temp = 12 kg * specific heat * 75 deg C I do not know specific heat in Joules or calories or kilocalories or whatever you are using in your class / kilogram deg C

**college alg.**

Different initial up speed but use : http://www.jiskha.com/display.cgi?id=1396965991#1396965991.1396967805

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