Thursday

April 24, 2014

April 24, 2014

Total # Posts: 16,220

**Physics**

m g h + (1/2) m v^2

**Pre-Calculus**

Go back and check your volleyball question. I just saw it and you missed the angle of launch in your equations.

**Pre-Calculus**

Hey Alexis, between the two of us we have been doing an awful lot of problems for you. Many of them are the same old, same old. It is time for you to try and post what you did.

**Pre-Calculus**

I got ( +36 , 24 , 39 )

**Science -Check Answers-**

You are welcome :)

**Science -Check Answers-**

first is ok second no by conservation of momentum the velocity will remain the same until an outside force ACCELERATES it F = m A

**math**

4 y = -x + 5 y = (-1/4) x + 5/4 so m, slope = -1/4 y = -(1/4) x + b 9 = -(1/4)(6) + b 36 = - 6 + 4 b 4 b = 42 b = 10.5 so y = (-1/4)x + 10.5

**math**

12/8 = 3/2 = 1.5 9 = 1.5 w = 3 w/2 w = 18/3 = 6 feet 6 ft (12 in/ft) = 72 inches

**Pre-Calculus**

t = x - 6 y = 2 (x-6) - 4 y = 2 x -16

**Pre-Calculus**

Oh, I see from your other questions you are not using vector notation x = 0 + t = t y = 4 + 6 t

**Pre-Calculus**

y = 6 x + 4 through point (0,4) slope = 6 well (0,4) + (1,6) t should work

**Pre-Calculus**

That is the resultant, but you need the opposite to that so move it around 180 to cancel it

**Math**

y(t) = -16 t^2 + 32 sin 35 t + 4.5 x = 32 cos 35

**Physics**

three masses m .18 m and m - .18 m = .82 m ----------------------- momentum = m Va forever so m Va = .82 m (0) + .18 m (v) v is relative to ground or Va = .18 v throw speed relative to moving cart = v - Va = .82 v v = Va/.18 = 5.56 Va new speed of baggage relative to ground = ...

**Math**

what you have is .7 , .75 , .4 , .5 , .67 so 2/5 , 1/2 , 2/3 , 7/10 , 3/4

**Alegbra**

.05 x + .08(5000-x) = 331

**math101**

I will assume you mean (1/4) x - 18 = (1/2) x - 6 then -18 + 6 = (2/4) x - (1/4)x -12 = x/4 x = - 48 If I misinterpreted, please repeat using parentheses to show what is numerator and what is denominator.

**math**

By the way, we know any angle greater than 45 degrees will cause a crash without doing any arithmetic. At 45 degrees the tree is 65 feet high.

**math**

yes, 65 tan 50 is 77.5 so crash

**Chemistry 2**

20 at t = 0 5 at t = 40 A = C e^kt 5 = 20 e^40 k .25 = e^40 k ln .25 = 40 k -1.39 = 40 k k = - .03466 so A = 20 e^-.03466 t when A = 10, we have not only the blank filled but the half life .5 = e^-.03466 t ln .5 = -.6931 = -.03466t t = 20 I think you can do it now

**Physics**

If it is at rest plane angle T from horizontal force down plane = m g sin T force up plane = mu m g cos T no acceleration so mu m g cos T = m g sin T or mu = tan T

**history (presidents)**

C is http://en.wikipedia.org/wiki/List_of_Presidents_of_the_United_States

**chemistry**

Pb(NO3)2 (aq) + MgCl2 (aq) ----> PbCl2 (s) + Mg(NO3)2 (aq) Pb++ + 2NO3- + Mg++ + 2Cl- ---> PbCl2 + Mg++ + 2 NO3- Mg and NO3 the same both sides, ions so net: Pb++ + 2 Cl- ---> PbCl2 solid

**Physics**

at rest so no net force force down plane = m g sin T force up plane = mu m g cos T so m g sin T = mu m g cos T so mu = tan T if friction just holds it

**physics**

On Jupiter 2900 * 2.53 or 2900 * 380.150 which is the same neptune 2900 * 1.18

**math**

cotangent * tangent = 1 ??????

**physics**

Hey, all these questions are really the same. I think you can do them now.

**physics**

m g where g is 6.5 m/s^2

**physics**

m g' at this altitude = 850 so g' = 850/470 = 1.81 m/s^2 we are way out there! 1.81/9.81 = Rearth^2/r^2 Re^2 = 6370000^2 = (6.37*10^6)^2 =40.6*10^12 so r^2 = 9.81 * 40.6*10^12 /1.81 r^2 = 220 * 10^12 r = 14.8 * 10^6 meters = 14,800 km r - Re = altitude = 8,430 km

**physics**

16 times 60 Hey, this is getting old

**physics**

if they were 1/5 as far apart? 25 times 45 same old 1/r^2

**math**

9.81/1.44 scroll down

**physics**

The rest is just to confuse the student by the way.

**physics**

F = G Mm /R^2 F' = G M m /(1.2R)^2 = G M m /R^2 * 1/1.44 9.81 * 1/1.44 = 6.81 m/s^2

**Chemistry 2**

BaCl2 + Na2SO4 ---> BaSO4 + 2NaCl Ba++ + 2Cl- +2Na+ + SO4-- --> BaSO4 + 2 Na+ + 2Cl- Na+ and Cl- same both sides so net: Ba++ + SO4-- ---> BaSO4

**Physics**

If you find out please tell me. I like meters, kilograms, seconds

**Physics**

m g h = 20 2 * 9.81 * h = 20 h = 1.02 meter rounding to 1 meter

**chem**

There are 2 O atoms in CO2 and 2 O atoms in O2 so the same 0.160 mol

**Science**

You need a course in hydrodynamics to explain how erosion and deposition cause meander and eventually cut off forming a horse shoe shaped lake.

**Science**

1. How does groundwater cause erosion and deposition? a. When acidic water soaks into the ground, water dissolves limestone, resulting in the formation of caves. *** ____________________ I agree if the question is about formation of caves. That is not what the question says bu...

**Science**

1. How does groundwater cause erosion and deposition? a. When acidic water soaks into the ground, water dissolves limestone, resulting in the formation of caves. *** b. When a river overflows, it moves downhill, resulting in the formation of caves. c. When it rains, water flow...

**world history 2**

That is why NY caught up to those earlier big cities, the cheap shipping to and from the west through the canal.

**world history 2**

The Erie Canal connected New York City up the Hudson River and through the canal to the Great Lakes. It is much, much cheaper to ship grain and stuff by boat than by road. So that opened up the mid west and made NY a big city.

**world history 2**

http://geography.about.com/od/urbaneconomicgeography/a/eriecanal.htm

**world history 2**

LOL, now how did New York City ever catch up to Philadelphia and Boston ?

**Science**

F = m a F up from scale - m g = m a but a = -g (free fall) so F up from scale - m g = - mg so F up from scale = 0

**Science**

Well, I agree because it says changes and the cat changed direction twice, once to turn around and once to go from horizontal speed to vertical speed, thereby changing velocity without much change in speed.

**science**

To continue moving in a circle requires an inward directed force from tension in a string or banking of a curve because the object is continually accelerating toward the center. If you let it go, it would go in a straight line. The constant acceleration toward the center is ca...

**world history**

http://www.fordham.edu/halsall/islam/1876suezcanal.asp

**world history**

French built it, British used it :) Trade between the Mediterranean Sea and Indian Ocean (India to Straits of Malacca to Spice Islands, to China) dates from long before the British or French existed. However it had to include a land link from the Nile to the Red Sea or from th...

**Physical Sciences**

constant velocity means NO ACCELERATION therefore just the weight 80 * 9.81 = 785 Newtons

**science**

Inertia is the word you are looking for I think.

**college algebra**

1.07 s = 44,490 s = 44,490/1.07

**6th grade math**

each combination of small tile and large tile covers 6 inches or 1/2 foot. So it will take 12 combinations to go 6 feet That is twelve four inch tiles and twelve two inch tiles just to stretch along the wall. NOW he needs two more 2 inch tiles for each of the original ones to ...

**Chemistry 2**

Al2(SO3)3 2 Al = 54 3 S = 96 9 O = 144 -----------add 294 grams/mol so 80 grams is 80/294 = 0.272 mol of aluminum sulfite in 50 mL a liter is 1000 mL 0.272 *1000/50 = 5.44 mols/liter

**college algebra**

800 - 300 = 500 profit I am wondering what is included in that cost though. If that is what she paid the wholesaler for the computer it is reasonable because cost of her building and help and taxes etc do not seem to be included.

**English**

Momentum is product of mass and velocity. At the same speed, the heavier object will have more momentum. I think this is Physics, not English, by the way.

**History check**

I agree although I usually think of them more positively as people who started the industrial revolution in the United States.

**mathematics**

x+2 = + or - 4 x+2 = 4 x = 2 or x+2 = -4 x = -6

**S.S**

French settled mainly the St Lawrence valley and there were not many of them because the king would not let the French Huguenots come to America.

**S.S**

Heavens, look at what I wrote about why Chinese and Japanese and others from Asia came to America !

**S.S**

note: "......... several huge copper mines opened, including Highland Valley Copper—the largest open-pit operation in all of North America. ..... "

**S.S**

http://www.empr.gov.bc.ca/Mining/Pages/History.aspx I think I already answered the second question. NOT Hawaiian !

**math**

population is 6,000 batches sample is batch examined

**S.S**

In particular in California many Chinese came to help build the transcontinental railroad. Does British Columbia have any railroads ? I think I have seen pictures of the Canadian Pacific route through the Rocky Mountains. Beautiful !

**S.S**

There are native Hawaiians of Polynesian ancestry. However there are many other groups there especially on Oahu including Japanese and Chinese and Philippine groups. These people immigrated from other parts of the Pacific to work in Hawaii. Similarly many Chinese people and Ja...

**S.S**

LOL - and many Hawaiians are from ______

**Physics**

on earth I assume weight = 850 * 9.81 in Newtons

**Physics**

72 km/hr *1000/3600 = 20 m/s average speed during acceleration = (20+0)/2 = 10 m/s 104 = 10 m/s * time to stop so time = t = 10.4 seconds

**mat 116**

So what is your known value of x ? multiply it by two then subtract 20

**Polynomial**

Yes

**Math**

tan^2 = sin^2/cos^2 = s^2/c^2 (s^2/c^2+1)(c^2-1) = s^2 -s^2/c^2 +c^2 -1 but s^2 + c^2 = 1 so we have -s^2/c^2 = -(1 - c^2)/c^2 = - 1/c^2 + 1 = 1 - sec^2

**Pre-Calc**

well I suppose x^2 = t^2 -6 t + 9 for x = t-3 and for x = 3-t but t = y-3 t^2 = y^2-6y+9 so x^2 = y^2-6y+9 -6(y-3) + 9 x^2 = y^2 + 36 y^2 = x^2-36 y = (x^2-36)^.5

**Algebra**

well, 7 d m = 7 d m b^0 You have it in DESCENDING not ascending powers of b -7dm + 25d b^5 - 6d b^6 + 3 b^10

**Pre-Calc**

b^logb(x) = x so 27^log(2x-1) = 27^(4/3) = 3^4 = 9*9 = 81 so 2x-1 = 81 2 x = 82 x = 41

**Math**

cos(pi/2+x) = - sin x (draw it on a graph , angle x to the left of y axis in quadrant 2) also sin - x = - sin x so we end up with (-sin x)(-sin x) = sin^2 x

**Science**

P V = n R T constant here so 550 mL/ 22 = 25 mL

**Algebra**

I meet all the ones that left during the 6 months before I left plus all the ones that left during my trip so about 12

**Trig**

sorry typo cos x cos y + sin x sin y 5 sqrt 7/52 + 9/13 = .9467

**Trig**

cos (x-y) = cos x cos y = sin x sin y cos x = -sqrt7 /4 cos y = -5/13 sin x = 3/4 sin y = 12/13 so cos(x-y)=5sqrt7/52 - 9/13

**Physics**

zero terminal velocity means constant speed down, no acceleration so approaching terminal velocity means approaching zero acceleration

**history**

I refuse to guess because I am from New England :)

**Math**

two heads tosses are independent .55 * .55 = .3025 probability of tails = 1-.55 = .45 two tails .45 * .45 = .2025 probability of 1 head + probability of 2 heads = probability of head, then tail + probability of tail then head + probability of two heads = 1 - probability of 2 t...

**Pre-Calc**

t^2 = x+1 y = x + 1 +/- (x+1)^.5 you can manipulate that further

**Algebra**

I just used 13 because I wanted easy numbers trying x = 15 now .5 y = 12 y = 24 so 15/24 yes 15-3/24 = 1/2 yes 15/30 = 1/2 yes so 15/24 is just as good as 13/20

**Algebra**

(x-3)/y = .5 x/(y+6) = .5 ----------------- .5 y = x - 3 .5 y + 3 = x these two equations are the same, choose any old x (infinite number of solutions) if x = 13 .5 y = 10 so y = 20 x/y = 13/20 check that (13 -3)/20 = 1/2 sure enough (13)/(26) = 1/2 sure enough

**Physics**

Do you know 45 degrees gives max distance? u = 4.9 cos 45 = .707 (4.9) = 3.46 m/s 12 = 3.46 t t = 3.47 seconds in air t going up = 3.47/2 = 1.73 s upward v = Vi - g t Vi = 4.9 sin 45 = 3.46 v = 0 at top 0 = 3.46 - g (1.73) g = 2 m/s^2 max height is average speed up time time u...

**Science**

yes, you are welcome.

**Science**

mass is matter

**Physics**

u = 86 cos 32 = 72.9 m/s forever Vi = 86 sin 32 = 45.6 up at start x distance = u t 265 = (86 cos 32) t t = 3.63 seconds in the air h = Hi + Vi t - 4.9 t^2 h = 0 + 45.6(3.63) -4.9(3.63)^2 h = 101 meters high v = Vi - 9.81 t at t = 3.63 v = 10 m/s up u = 72.9 still speed = sqrt...

**English**

or mimic or imitate, too bad it is not multiple choice :)

**math**

You are welcome :)

**math**

4 x + 10 y = 14 is the first equation times 2 4 x + 10 y = 14 is the second equation there is a y for any real x, in other words an infinite number of solutions since both equations are for the same line

**Physics**

How long to drop 42 - 2.12 = 39.88 meters? h = Hi + Vi t + (1/2) a t^2 0 = 39.88 + 0 - 4.9 t^2 t^2 = 39.88/4.9 so t = 2.85 seconds how far does he walk in 2.85 seconds? d = 1.12 * 2.85 = 3.2 meters

**Physical Science**

c = (5/9)(F-32) c = (5/9)(86-32) = 30 deg C I do not know what you are using, perhaps: V = 331.4 + .6 C V = 331.4 + .6(30) = 349.4 m/s d = 349.4 * 2.3 = 804 meters period = 1/653 lambda = 349.4 * 1/653 = .535 meter

**Physics**

110 km/hr(1000/3600) = 30.6 m/s 119 km/hr = 33.1 m/s x position of truck = -211.7+ 30.6 t v car = 2.3 t until v = 33.1 at t = 14.4 s and x = (1/2)(2.3)(14.4^2) = 238 m after that xcar = 238 + 33.1 (t-14.4) so during car acceleration period: d = Xcar - Xtruck = .5(2.3)t^2 - 211...

**Physical Science**

2 d = 1400 * .16 d = 112 meters deep 2 d = v t 2 * 1000 * 3.5 = 1400 t t = 5 seconds

**Mata**

half width is 39 feet up 2/3 of 39 2 * 13 = 26 feet <----- answer by the way, roofers go by pitch = height / full width so they would call this a pitch of 26/78 = 1/3

**Science**

Google- plate tectonics mountain formation -maybe?

**MATH**

y = 55 - 11 x or the way I would say it is depth = 55 - 11 * minutes since start the y axis intercept is the value of y when x = 0 It is 55. Now what does that 55 represent?

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