Thursday

January 19, 2017
Total # Posts: 28,803

**Social studies**

In North America it was the imported diseases from Europe that wiped out the natives. I suspect the same happened to the south.

*September 1, 2016*

**Social studies**

We are pretty proud of our public school history around here.

*September 1, 2016*

**History**

By the way, during most of WW2, I never really understood that the Japanese were enemy. I thought it was just Germans because I did not know any Germans. Japanese people were friends and neighbors in my life. It was impossible that they were bad guys.

*September 1, 2016*

**History**

They assumed that since they were Japanese in ancestry they might help the enemy Japan. It turned out to be nonsense. { My story: I was in Kindergarten in Honolulu when the Japanese bombed us. Many of my school mates and friends were Japanese Americans. In fact I think the ...

*September 1, 2016*

**History**

I bet you mean "code talkers". That usually refers to Navajo Indians who served the US Army in WW2 as communicators. Foreigners might be able to break most codes but had trouble with Navajo. See for example: http://en.wikipedia.org/wiki/Code_talker

*September 1, 2016*

**Statistics**

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

*September 1, 2016*

**chemistry**

Well, I suppose mass was conserved 10.2 + 66.9 = 77.1 ------------------------ You can stop there. ------------------------ Now let's check if they are in the right ratio 2 H2O ---> 2 H2 + O2 2 mols of H2 for every mol of O2 mol of H2 has mass 2 g mol O2 has mass 32 g ...

*September 1, 2016*

**science**

always multiply b something that is the same top and bottom except for the name of the unit for example 100 cm / 1 m is the same top and bottom so is 1 m/ 100 cm so if I have 105 m and I want cm I do 105 m (100 cm/m) = 10500 cm or 2000 mL (1 L / 1000 mL) = 2 L or 3400 g (1 kg/...

*September 1, 2016*

**Math**

slope = m = 4 y = 4 x + b -1 = 4(-5) + b b = 19 y = 4 x + 19

*September 1, 2016*

**Mathematics**

60 * 1/4 = 60/4 = 15 km 36 t = 15 t = 15/36 hour 15/36 * 60 = 25 minutes

*September 1, 2016*

**math**

boy does x jobs/day girl does y jobs/day (2 x + 5 y)4 = 1 job (4 x + 4 y)3 = 1 job 8 x + 20 y = 1 12 x + 12y = 1 2 x + 5 y = 1/4 2 x + 2 y = 1/6 ===============subtract 3 y = 3/12-2/12 = 1/12 y = 1/36 so a girl does (1/36) jobs /day find x and you know jobs/day a boy does If ...

*September 1, 2016*

**nor do I**

how much is a boy paid? boy does x jobs/day

*September 1, 2016*

**american history**

and was Maryland not a Roman Catholic colony at first?

*September 1, 2016*

**american history**

Oh , I missed no answer to 8 Most white colonists were farmers who prospered due to affordable land.

*September 1, 2016*

**american history**

1. I assume that you are talking about migrants from Asia across the North Pacific/ Bering Sea. These were nomadic tribes in general. 2 and 3 agree 4. I was not aware the the Dutch and French were fierce enemies particularly in North America. However they certainly did have ...

*September 1, 2016*

**Math**

(6/10 - 3/10)F = 60 3 F = 600 F = 200

*September 1, 2016*

**isoceles triangle?**

maybe? b + 2(b+7) = 95 3 b + 14 = 95 3 b = 81 b = 27

*September 1, 2016*

**physics**

mass of water = 44-18 mass of stuff = 39-18 density of stuff = 1 gram/cc * mass of stuff/mass ofwater

*September 1, 2016*

**Math**

24/10 - 13/10 = 11/10 = 1 1/10

*September 1, 2016*

**American government**

http://www.archives.gov/federal-register/constitution/

*September 1, 2016*

**math**

.31 + .20 = .51

*September 1, 2016*

**AP Biology**

http://www.chemspider.com/Chemical-Structure.84989.html 324.4 grams/mol so 100.7/275 = x/1000 x is grams in a liter divide x by 324.4 to get mols in a liter

*September 1, 2016*

**AP Biology**

22.4 liters/mol at stp so how many mols? 150/22.4 approximately (it does not say if we are at stp) grams of O2 = mols * 32

*August 31, 2016*

**Algebra 2**

L w = 51 2L + 2 w = 40 so L+w=20 51/w + w = 20 w^2 - 20 w + 51 = 0 w = [ 20 +/- sqrt (400 - 204)]/2 = [ 20 +/- 14]/2 so 3 by 17

*August 31, 2016*

**Forensics**

(1/2)^n = 1/16 n = 4 half lives 4 * 29 = 116 years if you did not see that 2^4 = 16 then you could do .5^n = .0625 n log .5 = log .0625 n = log .0625 / log .5

*August 31, 2016*

**Math**

50 + 100 = 150 m/h combined speed 150 t = 400 t = 40/15 = 8/3 = 2 2/3 hr = 2 hours and 40 minutes

*August 31, 2016*

**Technology**

Perhaps Livy is not using a keyboard and so can not look at those two keys closely.

*August 31, 2016*

**Technology**

I am puzzled. They are the keys your index fingers (not middle fingers) should rest on.

*August 31, 2016*

**Physics**

2.38*10^6 2.38 million = 2,380,000

*August 31, 2016*

**whoops sorry**

yes r = 0.05/52 weekly not daily !

*August 31, 2016*

**math**

.05 / 365 = r 4*52 = 208 = n x (1+r)^n = 3000 x = 3,000/(1+r)^n

*August 31, 2016*

**Algebra**

sqrt (17) real not natural not whole not rational not integer irrational

*August 31, 2016*

**math**

look up sinking fund formula r = .04/12 rate per month n = 10*12 = 120 months 250 = P /[ (1+r)n -1]/r so P = 250 [ (1+r)n -1]/r

*August 31, 2016*

**Math**

50(t-1) + 45 t = 330 95 t - 50 = 330 95 t = 380 t = 380/95 about 3 hours

*August 31, 2016*

**math work**

Maybe a vector 94 i + 93 j for example | 2 3 | |94| | 1 2 | |93| would be matrix times vector V = 94 i + 93 j

*August 31, 2016*

**watch parentheses!**

(2-x)/(2+x) maybe? if x = 2, numerator is zero, expression is zero if x = -2 Explodes, undefined

*August 31, 2016*

**math work**

do you mean u dot (v X w) ???? if so vXw = +i +j +k -6 +1 -5 +2 +8 -9 = (-9 +40)i + (-10-54)j +(-48-2)k -49i -64j -50 k now dot with + 9i - 7j - 3 k ---> -441 + 448 + 150 157 CHECK MY ARITHMETIC

*August 31, 2016*

**math work**

I think you mean orthogonal not octagonal a. vector normal (perpendicular to) first plane 4 i + 5 j +1 k second plane 3 i + 5 j -37 z find the dot or cross product dot is easier A dot B = |A||B| cos angle between if cos is 0, they are othogonal because cos 90 degrees is 0 if ...

*August 31, 2016*

**math**

You are welcome.

*August 31, 2016*

**math**

x = -2 + steps right y = -5 + steps up so x = -2 + 1 = -1 y = -5 + 3 = -2 (-1 , -2)

*August 31, 2016*

**Math**

65 + x = -12 x = -65 - 12 = -77 so 4

*August 31, 2016*

**?**

dilated how much?

*August 31, 2016*

**Math**

n and n+1 1/n + 1/(n+1) = 17/12 12(n+1) + 12 n = 17 n(n+1) 12 n + 12 + 12 n = 17 n^2 + 17 n 17 n^2 - 7 n - 12 = 0 hummm, suspect typo

*August 31, 2016*

**ah, magic ?**

I do not see the figure.

*August 31, 2016*

**Algera check answers**

Which of the following is the most appropriate unit to describe the rate at which data is transferred using the internet? =========================== Time needed is a function of megabits of data. D yes ========================== 2 + (x + y) = (2 + x) + y is an example of ...

*August 31, 2016*

**math**

4 10/15 - 3 6/15 = 1 4/15

*August 31, 2016*

**Physics**

50 * 9.81 * 2.4 = about 1200 J If you say g = 10m/s^2 you get exactly 1200 J

*August 31, 2016*

**Physics**

a = change in velocity/change in time = -20/4 = -5 m/s^2 F = m a = -300*5 = -1,500 Newtons

*August 31, 2016*

**math**

x^-n = 1/x^n 5 * 10^-2 = 5/10^2 = 5/100 = 0.05

*August 30, 2016*

**math**

( distributive property :)

*August 30, 2016*

**math**

if I have 100 dollars and increase that by 5% I then have 100*1 + 100*0.05 which is 100 (1.05)

*August 30, 2016*

**Physics**

s is initial speed Vi = s sin 6 v = Vi - g t at top v = 0 t = s sin 6 / 9.81 u = s cos 6 11 = u t t = 11/(s cos 6) so 11/(s cos 6) = s sin 6/9.81 solve for s, the initial speed get t then h = .39 + Vi t - 4.9 t^2 for part b u = s cos 6 new u = .25 s cos 6 then t to fall from h...

*August 30, 2016*

**Physics**

Now I did the squash one. Based on that you should be able to do this one.

*August 30, 2016*

**Pre-Calculus**

sec = 1/cos note cos is 0 at pi/2 so sec is undefined there (infinite + or -) in quadrant I cos is + so sec is + but in quadrant II cos is - so sec is - note cos always </= |1| so |sec| always >/= |1| that should help with your graph

*August 30, 2016*

**math**

It is divisible by 2

*August 30, 2016*

**Pre-Calculus**

y = sin x what values can x have? any real number right? y = sin^-1 x what values can x have? Only between -1 and + 1 right?

*August 30, 2016*

**physics**

you drove how long at 95? 180 km / 95 km/hour = 36/19 hour (45/10 - 36/19)hours at 65 about (90/20 - 36/20)65 = 54*65/20 = 175.5 km approximately 175 + 180 = 355 km approximately I do not feel like turning my calculator on. You can do it accurately.

*August 30, 2016*

**Math**

1 gallon (12 miles/0.3 gal) = 120/3 = 40 miles

*August 30, 2016*

**Math**

You are welcome.

*August 30, 2016*

**Math**

k^10 v^13

*August 30, 2016*

**Math**

4,020,561,340 add 0*10^0 4*10^1 3*10^2 1*10^3 6*10^4 5*10^5 0*10^6 2*10^7 0*10^8 4*10^9 :)

*August 30, 2016*

**History**

I would vote for the riches :) He was quite sure the world was round as were most navigators but he far underestimated the diameter and therefore thought he was in the East Indies when in fact he was in the West Indies :)

*August 30, 2016*

**Science**

All correct.

*August 30, 2016*

**Math**

60 person days/job (1/60) job/person day (1/60)job/person day *(4) persons = 4/60 job/day = 1/15 job/day so 15 days

*August 30, 2016*

**math homework**

5^2 + 12^2 + 9^2 = 250 length = sqrt 250 = 5 sqrt 10 so (1 / 5sqrt10) (-5,-12,9)

*August 30, 2016*

**typo, please check what youi posted**

-9, 12, 21 You have a typo Please proofread before you post http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

*August 30, 2016*

**Physics**

time outbound = d/48 time back = d/340 so d/48 + d/340 = 1.2 (.0208333 + .00294)d = 1.2 d = 50.5 meters

*August 30, 2016*

**Math**

q q * - n * - d * n q * - n :( - d :( d q * - n :( - d :( so 5/9

*August 29, 2016*

**Math - Check please!**

I agree you.

*August 29, 2016*

**ALGEBRA**

put these two points on a number line one is four to the left of zero and the other is 21 to the right of zero so the total distance between them is 21 + 4 = 25 or write 21 - (-4) = 21 + 4 = 25

*August 29, 2016*

**physics**

Xa = -5.3 + 8.1 t Xb = 4.7 - 7.8 t so when they meet Xa=Xb -5.3 + 8.1 t = 4.7 - 7.8 t 15.9 t = 10 so t = 10/15.9 then Xa = x for example = -5.3 + 8.1(10/15.9)

*August 29, 2016*

**Math**

6*9 = 54 so -54 beads

*August 29, 2016*

**Math**

done that above, -54

*August 29, 2016*

**Chemistry**

Dissolved 0.7500 g calcium chloride dihydrate and impure, in distilled water and the volume was elevated to 200.00 mL in a volumetric flask. A rate of 10.00 mL of the same consumed the titration 18.9 mL 0.0125 M EDTA using CALCON as indicator. What is the purity of the salt...

*August 28, 2016*

**physics**

What if the highway runs north-south?

*August 28, 2016*

**typo**

They have to tell you the mass.

*August 28, 2016*

**PHYSICS**

He ends up going 200 meters west in 252 seconds. Therefore we an figure out his west velocity component: Vw = 200/252 m/s Meanwhile he is carried south at .5 m/s so he will have to have a north component of Vn = .5 m/s So we can figure the angle north of west he has to head. ...

*August 28, 2016*

**physics**

weight down = 8 * 9.81 T up so m = hanging mass m a = F 8 a = 8*9.81 - T and top mass T = 5 a so 8 a = 8*9.81 - 5 a 3a = 8*9.81 a = 8 * 9.81/3 T = 5 * 8 * 9.81

*August 28, 2016*

**physics**

a = -3 m/s^2 v = Vi + a t at stop 0 = 20 - 3 t t = 20/3 (they should have started at 21 m/s) d = Vi t + (1/2) a t^2 d = 20 (20/3) - 3/2 (20^2/3^2) = 20^2/3 - 20^2/6 = 20^2/6 = 400/6 = 200/3 or easy way for second half is average speed during stop = 10 10 (20/3) = 200/3

*August 28, 2016*

**Maths**

y = 2x+8 y = 50 - x so 2x+8 = 50-x 3x=42 x = 14 y=36

*August 27, 2016*

**Math**

huh? (y2-y1) = -5-3 = -8 (x2-x1) = -2 +10 = 8 so slope = -8/8 = -1 so y = -1 x + b use either point now 3 = -1(-10) + b b = -7 so I get y = -x -7 ================ check that with the other point -5 = 2 -7 sure enough

*August 27, 2016*

**physics**

a = change in velocity/change in time = 495/1.78 m/s^2 braking is opposite velocity a = -495/2.16 m/s^2 note the acceleration of gravity is about 10 m/s^2 so this is more than 25 g,scary.

*August 27, 2016*

**Chemistry**

Dissolved 0.7500 g calcium chloride dihydrate and impure, in distilled water and the volume was elevated to 200.00 mL in a volumetric flask. A rate of 10.00 mL of the same consumed the titration 18.9 mL 0.0125 M EDTA using CALCON as indicator. What is the purity of the salt...

*August 27, 2016*

**physics**

weight = normal force = m g = 50 * 9.81 Newtons static force = .4 * 50 * 9.81 moving force = .3 * 50 * 9.81 assume use entire static force or it will not accelerate .1*50*9.81 = m a = 50 a so a = .981 m/s^2 v = a t = .981 * 5

*August 27, 2016*

**physics**

g = 9.81 m/s^2 v = Vi - g t at top v = 0 t = 25/9.81 seconds to top double that for time in air m g h = (1/2) m Vi^2 h = 625/(2*9.81) v is 0 at top of course a is -9.81 m/s^2 forever until it hits the mud.

*August 27, 2016*

**Computer Applications**

maybe something like this: n = 101 sum = 101 1 if n = 199 quit n = n+2 sum = sum + n go back to 1 quit ---> print the sum and end

*August 27, 2016*

**physics**

In the Google search engine input: 40 mph = km/h You will find 64.3738 km/h which is 62373.8 meters/h which is 62373.8 meters/h (1 h/60 min) in meters/min times 3 for 3 minutes 64.3738 km/h * 1 h/3600 s) * t = 1 km so t = 3600/64.3738 seconds

*August 27, 2016*

**Physics. Pleaseee helpppp**

calculate the potential energy in the center 4 k 2 Qe^2/half diagonal^2 then calculate it at the center of a side 2 k 2 Qe^2/ half side^2 + 2 k 2 Qe^2/diagonal^2 the difference in potential energy is the work done

*August 27, 2016*

**Physics**

short answer: 40% above water 60% below water :) long answer: volume of wood = 60 kg (1 m^3/600kg) = 0.1 m^3 volume of wood under water (see Archimedes) = 60 kg (1 m^3/1000kg) = 0.06 m^3

*August 27, 2016*

**Science**

step by step do [sqrt(16+9)]^2 = 5 sqrt(25+144) = sqrt(169) =13 or simply sqrt (16+9+144)

*August 27, 2016*

**math**

half length of diagonal = 8 look at B to center of that diagonal now have 8, 6, 10 right triangle area of that triangle = (1/2)8 *6 there are 4 of those trianges on the rhombus 16 * 6 = 96 or half product of diagonals (1/2)(16*12) = 96

*August 27, 2016*

**math**

http://www.wikihow.com/Calculate-the-Area-of-a-Rhombus

*August 27, 2016*

**Chemistry**

Dissolved 0.7500 g calcium chloride dihydrate and impure, in distilled water and the volume was elevated to 200.00 mL in a volumetric flask. A rate of 10.00 mL of the same consumed the titration 18.9 mL 0.0125 M EDTA using CALCON as indicator. What is the purity of the salt...

*August 26, 2016*

**math**

make a list take differences ---- 71 ** 16 87 ** 16 98 ** 16 110 the differences are all 16 71-16 is the answer :) 55

*August 26, 2016*

**Algebra**

It is a straight line when y = 0, x = 8 so put a dot on the x axis at x = 8 when x = 0, y = -8/5 = - 1.6 so put a dot on the y axis at y =-1.6 Draw a straight line through those two dots. The end

*August 26, 2016*

**MATH HELP**

|-3| = 3 |+3| = 3 so two numbers on a number line have the same absolute value , |-3| and |+3|

*August 26, 2016*

**Physics**

d = (1/2) g t^2 = 4.9 t^2 at t = 0, d = 0 at t = 1, d = 4.9 at t = 2, d = 4.9*4 at t = 3, d = 4.9 * 9 so from t = 1 to t = 3 it falls 4.9 (9-1) = 4.9*5

*August 26, 2016*

**Math**

60 = 10*6 = 5*12 12-5 = 7 remarkable

*August 26, 2016*