Saturday

May 23, 2015

May 23, 2015

Total # Posts: 21,027

**advanced physics**

at the top of the loop, the force between the track and the wheels becomes zero when the centripetal acceleration is the same as g g = v^2/R = 9.81 m/s^2 so at the top v = sqrt(R g) now we need the speed at the bottom of the loop that will give us that speed at the top ...
*May 22, 2015*

**Algebra**

perimeter = twice width + twice length area = length * width = (3√7 + 3√5 )(2√7 - 2√5 ) = 6*7 + 0 - 6*5 = 12
*May 21, 2015*

**Math- simple polynomials**

Yes, what Ms. Sue said. When you divide n pennies up evenly between n cups, you have ONE per cup.
*May 21, 2015*

**Calc 1**

I suspect you mean ∫ dt/(1-7t)^7, u=1-7t so if u = 1-7t then du = -7 dt or dt = -du/7 so we have ∫( -du/7)/u^7 or -(1/7) ∫ u^-7 du -(1/7)(-1/6) u^-6 (1/42) u^-6 + C 1/[42(1-7t)^6] + C
*May 21, 2015*

**algebra**

60/1 = 60 miles/hour 300/5 = 60 miles/hour sure looks like 60 miles/hour
*May 21, 2015*

**physics**

g is about 9.81 m/s^2 down F = m a here F = -9.81 m so m a = -9.81 m a = -9.81 m/s^2 or g downward v = speed up v = Vi - a t = 10 - 9.81 t so v decreases proportional to time until it reaches 0 at the top of its flight. Then it starts down. that time is t = 10/9.81 h = height...
*May 21, 2015*

**physics**

same current, add voltages
*May 21, 2015*

**math**

Ava 100 Brittany 75 Ava 100 - (9/20)100 = 100 - 45 = 55 Brittany 75+55 = 130 Ava = 55 + (1/4)130 = 55+32.5 = 67.5 Britanny = 130 -32.5 = 97.5 97.5 - 67.5 = 30 more
*May 21, 2015*

**Maths**

walked for t hours times are t and 3.75-t 4 t + 12(3.75-t) = 25 -8 t = 25 - 45 = -20 t = 5/2 d = 4 (5/2) = 10 km
*May 21, 2015*

**maths**

so how many more pieces than cuts? 72 - 53 = 19 bu you have one more piece than cuts so 18
*May 21, 2015*

**Trig**

13^2 = 169 5^2 = 25 169-25 = 144 12^2 = 144 so: cos T = -5/13 sin T = +12/13 T/2 will be in first quadrant sin(T/2) = [(1-cos T)/2]^.5 = [ (1+5/13)/2]^.5 = [9/13]^.5 yes 3. =
*May 20, 2015*

**science**

8. If a farmer plants the same crop in a field year after year, the soil becomes less fertile. What causes this decrease in fertility? (1 point) A.erosion B.lack of water C.loss of topsoil*** D.loss of nutrients I THINK D --- LOSS OF NUTRIENTS. C ALSO CAN HAPPEN...
*May 20, 2015*

**statistic**

Well, that was fun :)
*May 20, 2015*

**statistic**

p boy = .5 p not boy = 1-p boy = .5 sure looks like a binomial experiment to me lets find the probability of four boys out of ten births for example P(10,4) = C(10,4) .5^4 * (1-.5)^6 = 10!/[4!(6!)] *(1/16)*(1/64) = 210 / 1024 = .205
*May 20, 2015*

**algebra**

t = k/s 12 = k/60 k = 12*60 t = (12*60) / 85 or t = 8.47 hours
*May 20, 2015*

**Math**

0.035 * 3026 * 1.5
*May 19, 2015*

**mathematics**

http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html might work better
*May 19, 2015*

**mathematics**

https://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
*May 19, 2015*

**Math Please help!!!**

sure. It says he burns 420 calories every hour so in 1 hour, 420 in 2 hours , 840 etc The rest is just babble intended to confuse the enemy (student)
*May 19, 2015*

**Math Please help!!!**

420 t
*May 19, 2015*

**physics**

Of course that is just across the clock circuit, not including the battery itself. If you do a complete loop around any circuit the total potential changes add up to zero. That is fundamental to the meaning of potential of any sort, voltage, gravitational, elevation etc. In ...
*May 19, 2015*

**physics**

Mine too :)
*May 19, 2015*

**liberal arts math**

1080/4500 = x/100 = 1080/45
*May 19, 2015*

**physics**

500 * 20 / 50 in Joules
*May 19, 2015*

**physics**

75 * 9.81 * 1.75 Joules
*May 19, 2015*

**Phyics**

It is photons emmitted as electron drop from one discrete orbit to a lower energy orbit.
*May 19, 2015*

**math**

22+3 = 25 If there are several values of x with the same y, then if you turn it sideways there are many values of y for the same x and we can not write y = f(x) and get a unique answer. An example is a sine function y = sin x that is a perfectly good function, one y for each x...
*May 18, 2015*

**Chemistry**

mols of H2O produced = 5.671 /18 = .315 mols of CO2 produced = 36.933 /44 =.8394 Cx Hy Oz + n O2 ----> .8394 CO2 + .315 H2O well, y = .630 right off and x = .8394 z + 2 n = 2(.8394) + .315 = 1.99 but mass of O2 on left = 5.671+36.933-17.422 = 25.182 grams which is 25.182/32...
*May 1, 2015*

**Chemistry**

You have 5 O2 molecules for every 2 acetylene molecules P V = n R T where n (mols)is proportional to the number of molecules so for O2 125 (6) = 5 k R T for O2 P(3) = 2 k R T for C2H2 k R T are the same for both so 125(6/5) = P(3/2)
*May 1, 2015*

**algebra--1 question**

sqrt(w^2 + 25 w^2) = w sqrt (26)
*May 1, 2015*

**Chemistry**

P V = n R T At STP 1 mol is 22.4 liters so 3 liters =.134 mol of H2 There are 2 mols of Al for every 3 mol of H2 so mol Al = (2/3)(.134) = .0893 mol Al which is .0893 * 27 grams
*May 1, 2015*

**Differential Calculus**

v = Vi - 9.81 t 0 = Vi - 9.81 t at top Vi = 9.81 t = 19.62 meters/second Maybe get H as well falls for five seconds now h = Hi + Vi T - (1/2) g T^2 0 = Hi + 5 Vi - 4.9(25) Hi = 122.5 - 96 = 26.5 meters
*April 28, 2015*

**math**

11 s^2 = 1331 s^2 = 121 s = 11 the thing is a cube surface area = s^2
*April 28, 2015*

**math**

8.5 * 11 - 16
*April 28, 2015*

**phyiscs**

LOL !!! Your refrigerator has coils on the back that heat the room. 1. Motor compresses gas. Its pressure goes up but it gets HOT. 2. That hot pressurized gas goes through coils outside and behind the machine discharging the heat to the room and warming it up. 3. THEN the gas ...
*April 25, 2015*

**Math 222**

You can NOT factor that polynomial. You must either complete the square or equivalently use the quadratic equation you used the quadratic equation which is x = [ -b+/-sqrt(discriminant) ]/2a the discriminant is b^2 - 4 ac which is 9 + 20 = 29
*April 24, 2015*

**Science help**

I know nothing about magma but would pick liquid for minimal noise Do not need intensity as far as I know, triangulate using arrival times of waves.
*April 24, 2015*

**Science help**

microwave is RADIATION spoon is soup is conduction pasta moving is convection light waves is radiation
*April 24, 2015*

**Calc 1**

a when x = 9, function is vertical y--->oo when x is large negative or positive then y = 1 TRY NUMBERS! b dy/dx = [2x(x-9)^2 - x^2(2)]/(x-9)^4 = [2x^3 -38x^2 + 162 x]/(x-9)^2 the bottom is always + so the top is the whole thing if + then slope up, if - then slope down turns...
*April 24, 2015*

**physics 111 ????**

I scrolled all the way to the bottom and did not see any work by you so do not know where you got stuck. Surely you do not want to see if I can do them. I have been doing these since 1955.
*April 24, 2015*

**AP Physics**

Boats do not have backs. They have sterns or transoms. They also have bows. Anyway: Find original center of mass from the pier (not a dock but that term is actually often used these days for a pier). I will assume that the center of mass of the boat is 1.5 meters from the pier...
*April 24, 2015*

**Math**

Z score
*April 24, 2015*

**nope**

Described where?
*April 24, 2015*

**Math**

You are welcome.
*April 24, 2015*

**Math**

A B http://www.mathsisfun.com/data/standard-deviation.html
*April 24, 2015*

**physics 133**

1 Which of the following is the correct unit of k in the equation of a damped harmonic oscillator given as , where b is the damping factor and all the symbols have their usual meaning? ============================== F = - k x Newtons = -k * meters k is therefore in Newtons/...
*April 24, 2015*

**Math 222**

8). The polynomial for which you wish to find zeros is a^2 - 6 a + 9 = 0 Then I factored (a-3)(a-3) = 0 a = 3 or a = 3, in other words the vertex is on the x axis ============================= You could have completed the square (but it is already completed): a^2 - 6 a = -9 a^...
*April 24, 2015*

**Math**

LOL - if it came out 2/3, it is certainly not theoretical !
*April 24, 2015*

**physics**

charge = current in amps * time in seconds
*April 24, 2015*

**physics**

i = Q/t or amps = coulombs/second you do not need the electron charge for this - red herring intended to confuse you.
*April 24, 2015*

**DISCRETE MATH**

p fail = .2 p pass = .8 p five pass = .8^5 = .32768
*April 24, 2015*

**physics**

n * electron chsrge = 3.2*10^-6 Coulombs
*April 24, 2015*

**AP CALC**

d^2f/dx^2 <0 in other words curves down, sheds water
*April 24, 2015*

**Math**

6 sprinters 3 at a time but ORDER matters so we are talking permutations not combinations n!/(n-r)! = 6!/3! = 6*5*4 = 120
*April 23, 2015*

**Chemistry**

6.02*10^23 molecules/mol so 40.79kJ /6.02*10^23 molecules times I suspect you mean 8.51*10^10 molecules 40.79 (8.51/6.02)10^(10-23) 57.66 * 10^-13 or 5.766 * 10^-12 kJ
*April 23, 2015*

**no idea**

I have no idea what our experiment is.
*April 23, 2015*

**Algebra**

when y = 0 , x = 6 0 = 6m + b b = -6m so for the second one y = 3mx -6m when y = 0 6 m = 3 m x x = 2
*April 23, 2015*

**Math Help**

26 letters - 2 = 24 letters choice of 24 letters for first letter since letters can be repeated we have 24*24 = 576 letter combinations now we have ten numbers, 0 through 9 again they can be repeated (AA0000 is allowed) 10^4 = 10,000 so 576 * 10,000 = 5.76 * 1,000,000 = 5,760,000
*April 23, 2015*

**Math**

2^15 32768
*April 23, 2015*

**Math 222**

-x^2 + 3 x + 5 = 0 x^2 - 3 x - 5 = 0 x = [ +3 +/- sqrt(9 + 20) ] / 2 1.5 +/- 2.69
*April 23, 2015*

**Math 222**

a^2 - 6 a + 9 = 0 (a-3)(a-3) = 0 a = 3 or a = 3, in other words the vertex is on the x axis.
*April 23, 2015*

**Math 222**

a^(1/3) a^(3/2) a^(-1/2) a^ [ 1/3 + 3/2 -1/2 ] a^[1 1/3] or a^(4/3)
*April 23, 2015*

**Geometry**

V = k x^3 A = c x^2 for big one xb^3 = 1331/k for small one xs^3 = 216/k or xb/xs = (1331/216)^(1/3)= 1.83333333.... so xb^2/xs^2 = area ratio = 3.361111.... 484/3.361111... = 144
*April 23, 2015*

**World History**

alliances
*April 23, 2015*

**SOCIAL STDIES HELP!**

We checked all three.
*April 23, 2015*

**SOCIAL STDIES HELP!**

1. agree - roaring 20s until Oct 1929 2. NOT TV - happened when I was in elementary school LOL Electricity yes. stuff like washing machines was mostly after WW2. I remember rollers turned by hand to squeeze water out of laundry from tub. I suppose you could count that in which...
*April 23, 2015*

**Math 222**

eighth root of a^7
*April 23, 2015*

**Math 222**

sqrt 50 or sqrt(50 x^3) ?????? I will assume sqrt (50 x^3) 4 u sqrt(2*25) x sqrtx - x sqrt(2*16) sqrtx * u 20 u x sqrt(2x) - 4 u x sqrt(2x) 16 u x sqrt(2x)
*April 23, 2015*

**Physics**

first use conservation of momentum to get swing speed at bottom Vswing = Vbird (Mass bird/Mass swing) then m g h = (1/2) m Vswing^2 or h = Vswing^2/(2 *9.81)
*April 23, 2015*

**Math**

each term is half the previous one 1.6 *.5^(n-1) is a geometric sequence
*April 23, 2015*

**Precalculus**

in other words y = 4(n-1) = 4x - 4
*April 23, 2015*

**Precalculus**

(n+1,4n) from n = 0 to n --->oo seems to work
*April 23, 2015*

**chemistry**

NaNO3 = 23 + 14 + 3(16) = 85 g/mol 2.528/85 = .03 mol *1000 mL/.503mol = 59.1 mL
*April 22, 2015*

**chemistry**

.516 * 111.5/1000
*April 22, 2015*

**precalculus**

y^2 - 2 y = -x You were asked to eliminate the parameter t, not to solve for y. However I do not know the traditions of your particular group :)
*April 22, 2015*

**precalculus**

t^2 = 1-x t = y-1 so t^2 = y^2-2y+1 so y^2-2y+1 = 1 - x
*April 22, 2015*

**math**

http://www.jiskha.com/display.cgi?id=1429755553
*April 22, 2015*

**Math**

Draw it !!!!! call missing point P slope XY = (-2-6)/(5+1) = -8/6 =-4/3 so for XY y = -(4/3) x + something BUT WP has same slope y = -(4/3) x + b 3 = -(4/3) (-5) + b b = 3 - 20/3 = -11/3 3 y = -4x - 11 is WP Find YP the same way it is parallel to XW then find intersection of ...
*April 22, 2015*

**Math**

25*15 = 375 ft^2 1 yd = 9 ft^2 so 375/9 = 41 2/3 yd^2 41 2/3 * 20 = $833.33 no way , use cheaper carpet and install it yourself !
*April 22, 2015*

**math**

On a three day hike, Robert hiked twice as many miles on the first day as on the second day. On the third day he hiked 5 miles. Carlos hiked 5 miles on the first day and three times as many miles on the second day as on the third day. (a) Write and simplify an expression for ...
*April 22, 2015*

**pre-calculus**

t^2 = 1-x t = y-1 so t^2 = y^2-2y+1 so y^2-2y+1 = 1 - x
*April 22, 2015*

**pre-calculus**

hey, just pick some points note x^2+y^2 = r^2 = circle
*April 22, 2015*

**pre-calculus**

because I learned in a trig course the sin^2 x + cos^2 x = 1
*April 22, 2015*

**pre-calculus**

x = 1 + cos t y = 1 - sin t cos t = (x-1) sin t = (1-y) cos^2 t = (x-1)^2 sin^2 t = (1-y)^2 ----------------- add 1 = (x-1)^2 + (1-y)^2 your turn :)
*April 22, 2015*

**Math**

same slope (6-9) / (5+4) = (-1-y) / (-3-3)
*April 22, 2015*

**math typo I think**

I see Robert and Carlos but who is Matt?
*April 22, 2015*

**Math**

P is (0,T) slope of CD = 2/-3 = -2/3 slope of PC is then 3/2 so PC is y = (3/2)x + b at C, x = -3 and y = -6 -6 = 1.5 (-3) + b b = -6 + 4.5 = -1.5 so y = 1.5 x - 1.5 on the x axis when y = 0 x = 1 sp P at (1,0)
*April 22, 2015*

**Math**

2 = (0-12)/(a-4)
*April 22, 2015*

**history of math**

You are welcome.
*April 22, 2015*

**history of math**

s = 2 w w = 2 d so s = 4 d w = 2 d 4 d + 2 d + d = 100 7 d = 100 so d = 100/7 (not the wife) check if d = 100/7 w = 200/7 and s = 400/7
*April 22, 2015*

**Problem solving**

a + b = 7869 a - b = 1879 ------------ add 2 a = 9748 a = 4874 then b = 7869-4874 = 2995
*April 22, 2015*

**algebra 2**

s + a = 358 so s =358-a 1.5 s + 3.25 a =752.25 1.5(358-a) + 3.25 a = 752.25 find a then s
*April 22, 2015*

**7th grade math**

all correct 4. ratio of model to full scale is 1/25 1/25 = 3.8/h h = 25 * 3.8 = 95 yes
*April 22, 2015*

**calculus**

same as your fence really a + b = 40 so b = 40 - a P = a b = a(40-a) = 40 a - a^2 dP/da = 40 - 2 a a = 20 then b = 20 so 20 and 20
*April 22, 2015*

**PHYSICS**

well we agree on part a and part b is easy
*April 22, 2015*

**PHYSICS**

http://www.jiskha.com/display.cgi?id=1429748458
*April 22, 2015*

**calculus**

p + 2 q = 800 so p = 800 - 2 q A = p q = (800 - 2q)q A = -2 q^2 + 800 q now you could find the vertex of this parabola easily with Algebra 2 by completing the square but you said calculus so dA/dq = 0 at max = -4 q + 800 or q = 200 then p = 800 - 400 = 400 so A = 80,000 ft^2 ...
*April 22, 2015*

**PHYSICS PLEASE HELP**

http://www.jiskha.com/display.cgi?id=1429748458
*April 22, 2015*

**PLEASE HELP**

sorry, had to drop further to make up for friction m g h = -1902 -187 = -2089 Joules and h = 2089/(60.8*9.81)
*April 22, 2015*

**PLEASE HELP**

He must have been heading downhill ! change in kinetic energy = (1/2)(60.8)(8.12^2 - 1.84^2 ) = 1902 Joules energy in = -278 + 90.8 = -187.2 h = 0 initially m g h = - 1902 + 187 = - 1715 Joules h = -1715/(60.8*9.81) = - 2.88 meters so 2.88 is absolute value
*April 22, 2015*