Wednesday

January 18, 2017
Total # Posts: 28,793

**physics**

NOTE - acceleration is in m/s^2 NOT m/s Its horizontal velocity component does not change since there is no horizontal force u = 4 m/s Vertical Vi = 0 v = Vi + a t v = 0 + 4 * 2 = 8 m/s v = 8 - 12 (1) = -4 m/s so in the end u = 4 and v = -4 speed = 4 sqrt 2 direction = 45 ...

*October 2, 2016*

**Physics**

d = Vi t + (1/2) a t^2 = 20.5 mi/hr * 7.67 s + .5(7.96 mi/hr-s)(7.67^2 s^2) = [20.5(7.96) +.5(7.96)(7.67^2)]mi s/hr * (1 hr/3600s) = [20.5(7.96)+.5(7.96)7.67^2)]/3600 miles

*October 2, 2016*

**Physics**

HUH? What do you mean? if y = x^2 y does not equal m x + b I suppose you could plot log y = 2 log x that is easiest to do on log/log graph paper.

*October 2, 2016*

**Physics**

Now Google Newton's third law !!!

*October 2, 2016*

**Physics**

There is one equation, Newton's second law. Force = rate of change of momentum or if the mass is constant F = m A which is mass times acceleration F = .5kg * 4 m/s^2 = 2 Newtons 2 Newtons = 20 A A = 2/20 = 0.1 m/s^2 If you are taking physics, you better read the chapter!

*October 2, 2016*

**chemistry**

look up heat of vaporization of water.

*October 2, 2016*

**Math (Domain and range)**

also -oo to +oo

*October 2, 2016*

**physical science**

if you go 50 km in half an hour, how far do you go in an hour?

*October 2, 2016*

**Math**

10 boys 20 girls 30 total students 10/30 = 1/3 are boys

*October 2, 2016*

**Science**

If this is a wire or rod or something R = resistivity * length/area so four times the length is four times the resistance

*October 2, 2016*

**maths(Quantitative Method)**

sorry, put 1 on the diagonal, zeros off, to get inverse.

*October 2, 2016*

**maths(Quantitative Method)**

Yes, Steve's method gives you the inverse matrix as well as the solution

*October 2, 2016*

**maths(Quantitative Method)**

+2 -3 +1 +1 -1 +1 -4 +3 +3 -1 +0 +2 I assume this is from |+2 -3 +1| |a| +1 |-1 +1 -4| |b|=+3 |+3 -1 +0| |c| +2 solve for a b and c google gauss jordan

*October 2, 2016*

**AP physics**

direct straight line through origin with slope b AP Physics?

*October 2, 2016*

**Physics**

just do thee same old hanging problems with g = 9.81 + 1.7 or g = 9.81 + A obviously tension higher in top string

*October 2, 2016*

**Physics**

tension = T newtons bottom block: 6.7 g - T = 6.7 a top block on table: T = 4.1 a so 6.7(9.81) - 4.1 a = 6.7 a etc

*October 2, 2016*

**Physics**

weight ccomponent down slope F = m g sin 13.2 so m g sin 13.2 = m a so a = 9.81 sin 13.2 ( what else is new?) d = (1/2) a t^2 1.7 = (1/2) a t^2 solve for t then v = a t

*October 2, 2016*

**Physics**

force = change in momentum / time average speed = s = 10^5(6+2.6)/2 so time = t = .044/s F = 9.11*10^-31 (6-2.6)10^5 / t compare to m g

*October 2, 2016*

**Math**

x = e^(2y+4) - 4 ln(x-4) = 2y+4 y = [ ln(x-4) - 4 ] / 2 x better be bigger than 4

*October 2, 2016*

**Physics**

north: 3 -1 +2 +2

*October 2, 2016*

**Physics**

it is not accelerating therefore: Sum of forces in the x direction = 0 Sum of forces in the y direction = 0 Sum of moments around any point = 0 by the way 7 kg down is 7*9.81 Newtons down and tension in the line

*October 2, 2016*

**Physics**

1. Like the gravitational field of the earth if the object is the moon or the friction of tires on road if a car in a turn :)

*October 2, 2016*

**mathematics**

If I understand you first person gets x second gets .5 x third gets .25 x 1.75 x = 3500

*October 2, 2016*

**differential equation**

Oh, yes, the diff eq which everyone already knows the solution for da/dt = -ka da/a = - k dt ln a = -kt a = A e^-kt

*October 2, 2016*

**please type the whole problem**

How many after 2.5 ? x = Xi e^-kt x = 75 e^-2.5 k ln(x/75) = -2.5 k k = ln(x/75)/(-2.5) solve for k so ln .5 = -k t solve for t

*October 2, 2016*

**Physics**

m v^2/r

*October 1, 2016*

**Physics**

angle pushes car toward center, centripetal

*October 1, 2016*

**physics**

you do not say what the question is average rpm during stop = 1150 turns to stop = 1150 *2.9/60 original radians/s = 2300 revs/min*2 pi rad/rev *1min/60 s = 241 radians/s angular acceleration = -241/2.9 whatever

*October 1, 2016*

**Math**

10 x + 15 y = 2500 y = 195-x 10 x + 15(195-x) = 2500 10 x + 2925 - 15 x = 2500 5 x = 425 x = 85 y = 195-x = 110

*October 1, 2016*

**Math**

70*400 = 28,000

*October 1, 2016*

**Pre Cal help please!!**

given f(x) = { 2x^2 + 5 x < or equal to 2 3 - x^2 x > 2 What???? Perhaps you mean: given f(x) = 2 x^2 + 5 when x < or equal to 2 3 - x^2 when x > 2 if x is slightly bigger than 2 3 - 4 = -1 if x is slightly smaller than 2 OR if x is 2 then 2(4) + 5 = 8+5 = 13

*October 1, 2016*

**Physics**

24.5 x = 85.5(11.6-x)

*October 1, 2016*

**Physics**

I guess an intercontinental ballistic rocket is something "thrown over a large distance (on earth)" so 5. What a nutty question though :)

*October 1, 2016*

**maths**

(x^3+y^3)(x^3-y^3) (x^3+3x^2y+3xy^2+y^3)*(x^3-x^2y+3xy^2-y^3)

*October 1, 2016*

**Trigonometry**

in an hour he goes 1/24 of circumference (1/24)(2 pi *12,000/pi) = 24,000/24 = 1000

*October 1, 2016*

**Physics**

fast one takes t = 76/5.2 seconds slow one goes d = 2(76/5.2) so 76 - 2(76/5.2)

*October 1, 2016*

**simpson**

http://www.wolframalpha.com/input/?i=solve+dy+%3D+sin(x%5E2)+dx

*October 1, 2016*

**Physics**

Ac = v^2/r = 36/2 = 18 m/s^2 m F = M Ac = 51 *18 Newtons weight = 51 * 9.81 Newtons almost 2 g

*October 1, 2016*

**value**

change of momentum = .03*600 = 18 average speed = 300 time = .2/300 Force = change of momentum/change of time = 18 *300/.2 Newtons = 90*300 =27,000 agree

*October 1, 2016*

**maths sir-reiny help calculus**

Click on the step by step in Wolfram

*October 1, 2016*

**maths sir-reiny help calculus**

http://www.wolframalpha.com/input/?i=solve+x+y+dx+%3D+(x%5E2+-x+y+%2By%5E2)dy

*October 1, 2016*

**Algebra**

first scoop has 19 choices second has 18 choices cone has 3 choices 18*19*3

*October 1, 2016*

**Probability**

first ace 4/54 second ace 3/53 third ace 2/52 first king 4/51 second king 3/50 multiply them

*October 1, 2016*

**whoops**

30/54

*October 1, 2016*

**sorry**

30/54

*October 1, 2016*

**Math Help!**

7/54

*October 1, 2016*

**Science**

if near earth surface F = m g = 2.5 * 9.81 N and acceleration is g = 9.81 m/s^2 if at great distance r from earth center you need to do F = 2.5 G Mearth/r^2 so a = G Mearth/r^2

*October 1, 2016*

**math condense logs**

ln is log base e 3[ln x-2 ln(x^2+1)]+2 ln 5 ln a - ln b = ln (a/b) n ln x = ln x^n so 3 ln [ x/(x^2+1)^2] + ln 25 ln 25[ x/(x^2+1)^2]^3 so agree with Sam

*October 1, 2016*

**maths asap need help**

pi/6 = 30 degrees our lines go though a point 5 units along there from origin x = 5 cos 30 y = 5 sin 30 that 30 degree line has slope sin30/cos30 = .577 the perpendicular has slope -1/.577 = - 1.732 so line is of form y = -1.732 x + b now put in y = 5 sin 30 and x = 5 sin 30 ...

*October 1, 2016*

**Math**

1/4 of them seem to be rotten so 25

*October 1, 2016*

**algebra**

d = 16 t^2 at t = 6, d = 16*36 = 576 at t = 7, d = 16*49 = 784 784 - 576 = 208

*October 1, 2016*

**Physics**

half a period 14 t changes by pi say from 14t = 0 to 14t = pi or t = pi/14

*October 1, 2016*

**Math (Finding points of intersection)**

You are welcome.

*October 1, 2016*

**typo**

do you mean -x+y = 1 ????? so y=x+1 if so circle with center at (0,0) and radius 1 line through (0,1) and (-1,0) x^2 + (x+1)^2 = 1 x^2 + x^2 + 2 x + 1 = 1 2 x^2 + 2 x = 0 x(x+1) = 0 x = 0 or x = -1 line hits the circle at the x and y axis intersections

*October 1, 2016*

**I am having trouble with this homework question ,**

first add those up to see if they add to one Yes, they do so everyone has one of those 4 types THEREFORE probability not O = 1 - probability of O 1 - .53 = 0.47

*October 1, 2016*

**MATH HELP ASAP**

Just like the other one there are 7 females with A out of 75 students probability that student is female with A = 7/75 so probability not female with A = 1-7/75 = 0.907

*October 1, 2016*

**MATH 125 help**

Hey look, I just did the not a female with A. Now you do this one.

*October 1, 2016*

**Cards Probability**

7/13

*October 1, 2016*

**beats me**

I wish the math people would stay away from navigation. They are hopeless at distinguishing between bearing and heading and here they evidently think a boat moves with the wind like an airplane forgetting that the hull is in the water sort of like a car on a road in a ...

*October 1, 2016*

**PROBABILITY : M&M'S**

Randomly picking what Amanda, two reds and a green in three picks?

*September 30, 2016*

**question incomplete**

finish the sentence please

*September 30, 2016*

**PROBABILITY MATH HELP!!!!! DICE**

There are 6 sides 1,2,3,4,5,6 three of those are even 3/6 = 1/2 = 0.5

*September 30, 2016*

**Math**

17 - 33 = -16 wicked cold around zero Fahrenheit

*September 30, 2016*

**Algebra**

9. j-3=-7 A. j=-10 B. j=21 C. j=-4 D. j=4 🔹🔹🔹 NO!!!! add 3 to both sides, result negative

*September 30, 2016*

**Algebra**

5. 2/3x=6 A. x=9 B. x=4 C. x=18 D. x=12 🔹🔹🔹 NO, what on earth are you doing?

*September 30, 2016*

**Algebra**

4. -2c=-18 A. c=-9 B. c=-36 C.=9🔹🔹🔹 YES THIS TIME

*September 30, 2016*

**Algebra**

4. -2c=-18 A. c=-9🔹🔹🔹? B. c=-36 C. c=9 D. c=36 NO!!!!!!

*September 30, 2016*

**Social studies**

I agree.

*September 30, 2016*

**Maths,fractions**

(6/15 + 5/15 + 4/15)x = x looks like 15 to me. There is no smaller common denominator

*September 30, 2016*

**english**

Players usually kick or "head" none :) to their teammates on the field.

*September 30, 2016*

**Is it possible if you guys can check my algebra HW**

Yes, it is possible, but what did you do?

*September 30, 2016*

**Is it possible if you guys can check my algebra HW**

take x from bag 2 take 3x from bag 1 amount now in bag 2 = 100 - x amount now in bag 1 = 100 - 3x 100 - 3 x = (1/2)(100 - x) 200 - 6 x = 100 - x 5 x = 100 x = 20 so bag 1 = 100 - 3(20) = 40 bag 2 = 100 - 20 = 80

*September 30, 2016*

**Pre alg**

y = 3 x-11 x+y = 153 Is that what you mean? If so x + 3x-11 = 153 4 x = 164 x = 41 y= 112

*September 30, 2016*

**math**

ROFL !!!!! yes

*September 30, 2016*

**Spanish**

I am assuming the first one is asking what someone else is like, not "you" :)

*September 30, 2016*

**Spanish**

Even I can do the first one. it is not what is your name it is not how am I it is not how are you What are your answers?

*September 30, 2016*

**English**

trust or lack thereof is certainly a theme see http://study.com/academy/lesson/the-death-of-arthur-summary-themes-quiz.html

*September 30, 2016*

**Physics**

a = -.8 g v = 4 - .8(9.81) t at v = 0 t = 4/[.8*9.81)

*September 30, 2016*

**Advice and Consent**

In the United States the SENATE must approve treaties. The Supreme court can always find anything unconstitutional :) SEE: http://www.senate.gov/general/Features/Treaties_display.htm

*September 30, 2016*

**typo, Pascals**

Newtons/m^2 = Pascals

*September 30, 2016*

**Physics**

Vi = 30 sin 40 u = 30 cos 40 h = 0 + Vi t - 4.9 t^2 0 = 30 sin 40 t - 4.9 t^2 0 = t (30 sin 40 - 4.9 t) so t = 30 sin 40/4.9 for downrange time range = r = u t r = 30 cos 40 * 30 sin 40 /4.9 = 30^2 sin 80/9.8 so the first one :)

*September 29, 2016*

**History**

well B is just as unlikely as C :)

*September 29, 2016*

**typo**

5/9 * 4/8 = 20/72 = 5/18

*September 29, 2016*

**maths**

susan takes lemon then ann takes lemon: 5/9 * 4/8 = 20/72 = 5/13 susan takes orange then ann takes orange: 4/9 * 3/8 = 1/6 add them

*September 29, 2016*

**Math**

3 2/3 = 9/3 + 2/3 = 11/3 17/4 = 16/4 + 1/4 = 4 1/4

*September 29, 2016*

**math**

.02 * 30 = original amount of dry cucumber which does not change .11 x = .02 * 30

*September 29, 2016*

**Math hellppp!!**

You are welcome.

*September 29, 2016*

**Math hellppp!!**

I get your parentheses right (-12/3)*(-8+(-4)^2-6)+2 -4^2 = 16 -8+16-6 = 2 -12/3 = -4 -4* 2 = -8 -8 + 2 = -6

*September 29, 2016*

**Math**

so what is 5^3 ?

*September 29, 2016*

**Math**

96/2 = 48 48/2 = 24 24/2 = 12 12/2 = 6 6/2 = 3 so 3*2^5 what is 5*5*5 ?

*September 29, 2016*

**Math**

let y = f(t)/2.7 to make it easy y = 1.004^t ln y = t ln 1.004 = 0.00399 t e^ln y = y = e^.00399 t so f(t) = 2.7 y = 2.7 e^.00399 t

*September 29, 2016*

**Social Studies Religion**

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; ........ If it does not ring a bell, use Google :)

*September 29, 2016*

**History PLEASE CHECK MY WOrK**

I agree with you.

*September 29, 2016*

**History**

Portuguese owned Brazil. Brazil had manioc. Portuguese took it to Africa. A

*September 29, 2016*

**History**

still A Google manioc Portuguese Brazil

*September 29, 2016*

**CHECK MY ANSWERS American Government**

1. agree but this ignores alternate path through constitutional conventions. 2. I guess you are right but am tempted by the first choice. I agree with the others.

*September 29, 2016*

**Grammar**

....and then there is that subjunctive "would" .... :)

*September 29, 2016*

**History**

http://agron-www.agron.iastate.edu/Courses/agron212/Readings/Corn_history.htm by the way American tribes were so thinly spread out that even if every single person one died it would have been just a blip in global population

*September 29, 2016*

**History**

Yes A, like corn You are welcome.

*September 29, 2016*

**History**

Oh come on! Native Americans did not have gunpowder. The European invaders did. Both had bows and arrows and hatchets. The Spanish horses were their best weapon though. Of course blowguns were kind of unusual in 17 th century Europe but I am not sure that is what we are ...

*September 29, 2016*