Thursday

July 28, 2016
Total # Posts: 26,563

**world history**

First of all, who says? Although the habit is to treat Chinese dynasties as succeeding, there is no reason they should not have overlapped. That said, they had, as the Chinese always had, nomadic tribes to the north and west and the bleak ocean to the east. Mostly mountains ...
*July 27, 2016*

**science(physics)**

momentum = 0.100 * 20 = 2 kg m/s distance into plank = .020 meter average speed in plank = 20/2 = 10 m/s time in plank = .020/10 = .002 s average force = change in momentum/time = 2/.002 = 1000 Newtons
*July 27, 2016*

**math**

(9/36)*900 = 900/4 = 225
*July 26, 2016*

**Math**

This is not a submarine but a research submersible. Submarines do not go much deeper than a couple of boat lengths. 8 * 60 + 37 = 517 seconds 517 seconds * 25 ft/s = 12,925 feet Although that is far deeper than a submarine dives, it is less than half as deep as the Mariana ...
*July 26, 2016*

**Chemistry**

How much H3PO4 is needed to neutralize 1 liter of a 0.75M solution of NaOH? (in moles)
*July 26, 2016*

**Math**

8 sin 30 + 8 sin 120 8 (1/2) + 8 (1/2) sqrt 3
*July 26, 2016*

**math**

must be combined age? p = 2 j p-17 + j-17 = 33 p + j = 67 2 j + j = 67 3 j = 67 j = 67/3 = 22 1/3 so p = 134/3 = 44 2/3
*July 26, 2016*

**physics**

h = Hi + Vi t - 4.9 t^2 v = Vi - 9.81 t when is v = 0 ? (the top) t = 30/9.81 = 3.06 seconds coasting up to a stop so h = 50 + 30 (3.06) - 4.9 (3.06)^2
*July 26, 2016*

**Physics**

You kidding? 200 - 3(45)
*July 26, 2016*

**physics**

v = Vi - 9.81 t h = Hi + Vi t - 4.9 t^2 42 = 0 + Vi(2) - 4.9(4) Vi = 30.8 meters/ second when it hits ground, v = -30.8 m/s v = Vi - 9.81 t -30.8 = 30.8 - 9.81 t t = 6.28 seconds
*July 25, 2016*

**Chemistry**

Thank you so much!
*July 25, 2016*

**Chemistry**

What volume of nitrogen dioxide (in L) is produced from the complete reaction of 16.87 of lead (ii) nitrate at STP
*July 25, 2016*

**college physics**

time for one wave = period = 1/f = 10/30 so f = 3 Hz
*July 25, 2016*

**physics**

u = 10 m/s forever v = -gt = -9.81 (3) = - 29.4 m/s check if it hit the ground d = (1/2) g t^2 = 4.9 * 9 = 44.1 so still in the air speed = sqrt (10^2 + 29.4^2)
*July 25, 2016*

**Maths**

a + 20 = 3 (180-a) a + 20 = 540 - 3 a 4 a = 520 a = 130 180-a = 50
*July 25, 2016*

**Maths**

(n + m)/2 = 15 so n + m = 30 m = (30-n) (n m )^.5= 9 n m = 81 n(30-n) = 81 -n^2 + 30 n = 81 n^2 -30 + 81 = 0 (n-3)(n-27) = 0 3 and 27
*July 25, 2016*

**General Mathematics**

http://www.jiskha.com/display.cgi?id=1469428320
*July 25, 2016*

**Maths**

7 +8 +3 = 18 so 2 are white 2/20 = 0.1
*July 25, 2016*

**huh? typos?**

maybe 2 meters deep and find volume not height? if so v = w L d = 20 *100 *2 = 4,000 m^3
*July 25, 2016*

**Math (Rational Inequality)**

x^2 h = 8 x = sqrt(8/h) if h = x x = h = 2 if x > h, not allowed if x < h then h > 2 so x < 2
*July 25, 2016*

**algebra**

Well, you know 48 = 16*3 You know that 3/3 = 1 so multiply 3/16 by 3/3 and get 9/48
*July 25, 2016*

**ststistics**

binomial distribution p = .24 1-p = .76 n = 10 P(2) = C(10,2).24^2 (.76^8) but C(10,2) = 45 so 45 * .0576 * .111 = .288 P(1) = 10 * .24 * .76^9 = .203 so answer to b is 1 - .288 - .203 c is same way but boring. you do it
*July 25, 2016*

**Hey wait a minute**

This is very, very similar to one I already helped you with. Please try them yourself. It does not do you any good to have us do all the problems for you. The idea is that we can help, but not do virtually the same problem over and over for you. http://www.jiskha.com/display....
*July 24, 2016*

**MATH**

let x = tan t then dx = sec^2 t dt sec^2 t dt/[ tan t (1+tan^2 t) ] NOTE: 1+tan^2 t = sec^2 t !!! wow that helps :) so we have dt/tan t = ctn t dt = ln (sin u)
*July 24, 2016*

**Math**

u = 1 - y^2 du = -2 y dy or dy = du/-2y ((y^3)/(u^2))[du/-2y] (-1/2)y^2 du/u^2 but y^2 = 1-u so -(1/2)(1-u) du/u^2 = (u/2)du/u^2 - (1/2)du/u^2 = (1/2) du/u - .5 u^-2 du finish and check my arithmetic :)
*July 24, 2016*

**Someone Please Help me- PreCalc**

x^2 + y^2 = 1 16/49 + y^2 = 49/49 y^2 = 33/49 y = +/- sqrt (33) /7 so since in Q IV where y is negative (4/7, -sqrt(33)/7 )
*July 24, 2016*

**physics**

10 * 100
*July 24, 2016*

**physics**

potential energy at top = kinetic energy at bottom m g h = (1/2) m v^2
*July 24, 2016*

**maths**

24 + 5 - 17
*July 24, 2016*

**Physics**

Oh, do cos wt = -1/2 as well
*July 24, 2016*

**Physics**

x = X sin w t v = X w cos w t so X w cos w t = (1/2) X w cos w t = 1/2 w t = 60 degrees, 300 degrees etc or in radians pi/3 etc so what is x/X when wt = pi/3 etc x/X = sin wt x/X = sin 60, 300 etc x/X = .866 , -.866 etc
*July 24, 2016*

**Math**

x + 24 = 36 ?? -24 = -24 ---------------add x + 0 = 12 so x = 12
*July 23, 2016*

**Math**

.3(10) = 3 .3(10+10) = 3+3 = 6 .3(10+10+10) = 3+3+3= 9
*July 23, 2016*

**physic**

kinetic energy = (1/2) m v^2 that goes into heating the brakes (use Joules not calories) energy =specific heat*mass*(Tend-Tbegin)
*July 23, 2016*

**Science**

(1/2) m v^2 = (1/2)(1/2)(9) = 9/4 Joules
*July 22, 2016*

**math**

first blue: 6/16 second blue 5/15 so 3/8 * 1/3 = 1/8 = 0.125
*July 22, 2016*

**math whoops 4/13**

sorry, 4/13
*July 22, 2016*

**math**

careful !
*July 22, 2016*

**math 11/36**

http://davidmlane.com/hyperstat/A136602.html
*July 22, 2016*

**math**

Yes,note unlike the other two questions because red and spade are mutually exclusive
*July 22, 2016*

**physicis**

metal A length x metal B length (15-x) x(4.3)(pi r^2) + (15-x)(6.3)(pi r^2) = 21757 4.3 x + 94.3 - 6.3 x = 21757/(81 pi) 2 x = 8.8 x = 4.4 cm
*July 22, 2016*

**Physics**

m = 670/g = 670/9.81 = 68.3 kg F = G m Ms/(r^2) F=6.67*10^-11*68.3*1.99*10^30/7500^2
*July 22, 2016*

**stats**

http://davidmlane.com/hyperstat/z_table.html
*July 22, 2016*

**PHYSICS**

well, I am just going to estimate iron density about 8 times water 8000 kg/m^3 or 8 g/cm^3 8 L pi r^2 = 8(85)(3)(2.5)^2 about 8 * 85 *3 * 6.3 or 12852 grams 12.8 kg no problem :) less than 30 pounds
*July 22, 2016*

**maths**

n cupcskes n/6 to neighbor , 5n/6 remain (7/10)(5n/6) to sister or 7n/12 to sister (3/10)(5n/6) remain or n/4 remain so n/4 =12 n =48
*July 22, 2016*

**Physics**

How high does it go? v = Vi -9.81 t at top v = 0 0 = 14 -9.81 t so t = 14/9.81 then h = 100 + 14 t - 4.9 t^2 now fall from h v^2 = 2 g h
*July 22, 2016*

**Algebra**

x and (60-x) 2 x -.5(60-x) = 10 2 x -30 +.5 x = 10 2.5 x = 40 25 x =400 x = 16 60-x = 44
*July 22, 2016*

**Algebra**

(y-a)^2 = y^2 - 7 y + p y^2 - 2 a + a^2 = y^2 - 7 y + p 2 a = 7 a = 7/2 so p = a^2 = 49/4
*July 22, 2016*

**Physics,Mthe**

mass/volume = density =100/10 = 10 but you have given no units so it could be anything at all.
*July 22, 2016*

**Physics**

I am not going to just give you the answers to these very basic questions. Try yourself and maybe someone will help if you get messed up.
*July 21, 2016*

**No way !**

No, I refuse to just answer. You say and tell us why. What do you think? What is the difference between mass and weight? Would it be different at different locations in the body?
*July 21, 2016*

**American History**

Budgets cuts in our Defense has led to inefficient weapons available to the soldiers to fight wars here in America or Overseas. ??????????????????? Please compare US defense budgets and resulting weaponry to those of other countries.
*July 21, 2016*

**Math**

For what value(s) of r is r^2+5r+6/r+2 equal to 0? A) -2 only B) -3 only C) 3 only D)-2 or -3 E) 2 or 3 I got A but it is incorrect and I'm still confused Thanks
*July 20, 2016*

**Chemistry**

How many grams of hydrogen peroxide (H2O2) must be added to 1,500 ml of water to produce a concentration of 1.33 m (molal solution)?
*July 20, 2016*

**Math**

checks at http://www.mortgagecalculator.org/
*July 20, 2016*

**Math**

payment = principal [ r/ (1 - {1+r}^-n) ] here principal = 200,000 r = .10/12 = .0083333333..... n = 25*12 = 300 = 200,000 [ .00833... / (1-{1.00833..}^-300) ] = 200,000 [ .009087 ] = 1817.40
*July 20, 2016*

**math**

7 * 9 = 63 315/63 = 5 so 7 * 9 * 5 = 315
*July 20, 2016*

**Geometry**

y = 2 x - 5 to y = 2 x moves up 5
*July 20, 2016*

**Math**

have played x have won .75 x will have won .75 x + 4 will have played x + 4 so .75 x + 4 = .80 (x +4) 4 - .8*4 = .05 x 4 - 3.2 = .05 x .8 = .05 x 800 = 5 x x = 160
*July 20, 2016*

**Algebra**

c^2 + 18 c - 175 = 0 (c + 25)(c - 7) = 0 c = 7 or c = -25
*July 20, 2016*

**statistics**

15951/13 = 1227 per yesr
*July 20, 2016*

**Math**

7 1/2 = 15/2 15/2 / 3/4 = 30/3 = 10 =============== or 10 * 3/4 = 30/4 = 7 1/2
*July 20, 2016*

**algebra**

Well, if the denominator is constant and x is alone up there (no x^2 or sin x or anything) then yes
*July 19, 2016*

**Northwest is not 30 deg n of e**

when you get the geometry figured out look at: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/forwir2.html
*July 19, 2016*

**Nobody knows**

we do not know what the dimensions were on the plans, or alternately the area. If you know the area on the plan, A in^2 then Areal = A (9 ft^2/6.25 in^2)
*July 19, 2016*

**physics**

Well, you could use Maxwell's equations, but it might be easier to make a common sense guess. If moving the magnet makes a voltage, then it is likely that moving it faster will make a bigger voltage.
*July 19, 2016*

**Physics**

ps: That is what potential is all about.
*July 19, 2016*

**Physics**

exactly as much as to slide down one mountain and up the one beside it to the same height, with no friction of course.
*July 19, 2016*

**Math**

71/163 = F/756 so F = 756 * 71 / 163
*July 17, 2016*

**Maths**

21 - 13 = 8 play only C 16 - 13 = 3 play only F 8+3+13 = 24
*July 17, 2016*

**University of jos,physics**

ROFL zero, went nowhere Now average speed is another matter.
*July 17, 2016*

**Math**

I think it is just folded three times so the short edges can be welded together. No top and bottom yet
*July 17, 2016*

**Math**

height = 20 side length = 36/4 = 9 volume = 9*9*20 cm^3 top = 81 cm^2 bottom = 81 cm^2 81 * 2 = 162 cm^2
*July 17, 2016*

**University of jos,physics**

distance = sqrt (3^2 + 4^2) = 5 sin angle north of east = 3/5 = 0.6
*July 17, 2016*

**University of jos,physics**

h = (1/2) g t^2 if g = 9.81 h = 4.9 (25)
*July 17, 2016*

**Physics**

The link tells you right off. 2.25*10^8 instead of 3*10^8
*July 17, 2016*

**Physics**

http://www.google.com/search?q=velocity+of+light+in+water&ie=utf-8&oe=utf-8
*July 17, 2016*

**Physics**

What are you using for c? The velocity of light in water is lower than in a vacuum, which you know I am sure from your experience trying to shoot fish with a bow and arrow. If you are using about 3*10^8 m/s, that is wrong.
*July 17, 2016*

**typo ?**

"perimeter 10 meters " I guess maybe you mean ten times but it is still nonsense 1000 = 25 L so L = 40 m 1000 = 10 ( L+w) 100 = 40 + w so w = 60 area = L * w obviously there is something wrong. width bigger than length
*July 17, 2016*

**math**

5 maybe ?
*July 17, 2016*

**pre cal**

well g = x^2 + anything will work. Steve used zero
*July 17, 2016*

**pre cal**

where are the zeros of this parabola? x^2 + 6 x + 18 = 0 x = [-6 +/- sqrt (36-72)]/2 = -3 +/- 3 vertex is at x = -3 g has it at at x = 0 how high is it? roots are not real so above x axis y = (-3)^2 -18 +18 = 9 so to be even g(x) = x^2 + k when x = 0, y must be 9 so g(x) = x^2...
*July 17, 2016*

**math**

7!/[ 3! * 4! ] 7 * 6 * 5 / 3*2 35 all right
*July 17, 2016*

**Math**

total approach speed = 127 km/h 635 / 127 = 5 hours
*July 17, 2016*

**Chemistry**

choices A. H>0, S>0 , G<0 B. H<0, S>0 , G<0 C. H>0, S>0 , G>0 D. H<0, S<0 , G>0
*July 16, 2016*

**Chemistry**

Marcela dissolves 80.0 g of ammonium nitrate in 50.0 mL of water at room temperature and notes that the temperature of the solution decreases by 5.0°C. Which correctly designates the signs of changes of G, S and H for this reaction?
*July 16, 2016*

**Missing data for binomial distribution problem**

We need to know how many she planted. Given n, use binomial distribution with p = 0.95 and 1-p = 0.05
*July 16, 2016*

**math**

http://www.jiskha.com/display.cgi?id=1468692682
*July 16, 2016*

**math**

red each is 3/20 green each is 4/40 which is 1/10 so 10(3/20) + 50(1/10) = 1.50 + 5.00 = 6.50 ah well, not on the list. Typo?
*July 16, 2016*

**math**

let me see 5 7 11 13 I think mean = (5+7+11+13)/2 = 36/4 = 9 median = (7+11)/2 = 9 When there are an even number of items it is impossible to pick the same number above and below any particular one. Therefore you take the average of the two middle ones.
*July 16, 2016*

**physics**

original is r v = 5 r then later same v = 4 (r+2) so 5 r = 4 r + 8 r = 8 ohms
*July 16, 2016*

**no, physics :)**

9 because 3^2 = 9 or because 3 s has 1 3 p has 3 3 d has 5 and 1 + 3 + 5 = 9 Note, each of those orbits can have electrons with spins of + or - 1/2 so total of 18 electrons for n = 3
*July 16, 2016*

**statistic**

3 b 2 b, 1 g 1 b, 2 g 3 g so 4 possible outcomes, all equally likely p of each is .25
*July 15, 2016*

**Geometry**

6.75 in (1 ft/.25 in) = 27 ft 4.50 in (1 ft/.25 in) = ?????
*July 15, 2016*

**calc**

Angle to what? Not knowing do not know sin or cos F (cos 48 or sin 48)(0.45) = 175
*July 15, 2016*

**Physics**

Ah yes, just noticed you said 5, good
*July 15, 2016*

**Physics**

C =q/V so x = q/68 that q is all the charge we have now for both capacitors total C = 12*10^-6 + x q = 20 (12*10^-6 + x) 68 x = = 240*10^-6 + 20 x 48 x = 240 * 10^-6 x = 5 *10^-6 Farads or 5 µF
*July 15, 2016*