Wednesday

December 7, 2016
Total # Posts: 28,399

**Physics**

a. 40 m/s down potential energy = m g h same h so same potential energy so same kinetic energy (1/2)m v^2 b. how long up 0 = 40 - g t t = 40/9.81 2 t = time up + time down = 80/9.81 a parabola, sheds water y = 40 t - 4.9 t^2

*October 2, 2016*

**physics**

m v^2/r v less --> force less

*October 2, 2016*

**Physics 12**

710 cos 32 horizontal 62*9.81 - 710 sin 32 vertical I doubt it though, tension seems too low

*October 2, 2016*

**Math (Limits)**

Yes, if g(x) = x then if x is pi so is g(x)

*October 2, 2016*

**Math (Limits)**

I do not know what g(x) is perhaps it is g(x) = 15 x + 27 x^15 for all I know in that case g(pi) = 15*pi + 27 * pi^15

*October 2, 2016*

**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*