Monday

April 27, 2015

April 27, 2015

Total # Posts: 20,993

**Physics**

before North (y) momentum =2300(14) - 1600 (16) cos(270-225) = 32,200 - 18,101 = 14,098 kg m/s East(x) momentum = 0 =18,101 = -18,101 after same momentum, but mass is 2300+1600 = 3900 kg East (x) = 3900 * Vx = -18,101 North (y) = 3900*Vy = 14,098 so Vx = -4.64 m/s Vy = 3.61 m/s
*November 25, 2014*

**U.S. History**

I was not aware of a "league of friendship".
*November 24, 2014*

**physics (would mr. sue or mrs damen answer my ques**

Not unless you give us the heat of fusion of water and the specific heat of water and silver. mass silver * specific heat of silver * (107-T) = heat of fusion of water * mass of ice
*November 24, 2014*

**liberal arts**

whoops sorry, forgot that he works at night. 2 * 4 = 8 then out the next day, 5 days
*November 24, 2014*

**liberal arts**

two feet every 2 days until we get within five 2*4 = 8 in 8 days now the ninth day we go up to 8+5 = 13 so we are free after 9 days
*November 24, 2014*

**Physics**

you did not give me the frequency or anything.
*November 24, 2014*

**math problem (please help)**

2 w + 2 L = 70 so w+L = 5 and L = (35-w) 300 = w (35-w) w^2 -35 w + 300 = 0 (w-20)(w-15) = 0 w = 15 or 20 so w = 15 and L = 20
*November 24, 2014*

**physics**

10 log I1/I2 = 10 log (102/408) = 10 log .25 = -6.02 so 6 lower
*November 24, 2014*

**physics**

G M m/r^2 = m g = 50 G M /r^2 = g = 50/30
*November 24, 2014*

**physics**

a = F/m = (7-3) * 10^4 / (1.3*10^5)
*November 24, 2014*

**physics**

I2/I1 = R1^2/R2^2 = 5^2/(10^4)^2 = 25 * 10^-8 10 log (25*10^-8) = 10 [-8 + 1.4] = - 66 dB 103 - 66 = 37 dB still pretty loud
*November 24, 2014*

**Math I need help ASAP! I'm getting timed**

Which ratios form a proportion? 1. 4/12 , 6/8 2. 16/12 , 3/4* 3. 3/2 , 15/14 4. 10/16 , 5/8 10/16 = 5/8 Which ratio forms a proportion with 9/15? 1. 6/10 2. 16/21 3. 36/50 4. 45/70 9/15 = 3/5 which is 6/10 A textbook weighs 2.5 pounds. How many kilograms does the textbook ...
*November 24, 2014*

**physics**

1. zero is correct 2. yes, any force up from the floor has no moment arm 3. change in Pe = m g h = (1/2) m g L Ke = (1/2) m v^2 + (1/2) I w^2 I = (1/12) m L^2 v = (L/2)w so Ke = (1/2)m(L^2/4)w^2 + (1/2)(1/12)m L^2 w^2 = (m L^2 w^2) (1/8 + 1/24) = m L^2 w^2 (1/6) so (1/2) m g L...
*November 24, 2014*

**math calculus**

agree
*November 24, 2014*

**calculus**

s = (6t+3)^.5 ds/dt = .5 (6t+3)^-.5 (6) = 3 (6t+3)^-.5 d^2s/dt^2 = 3 [ -.5(6t+3)^-1.5 *6) = -9 /(6t+3)^1.5 if t = 1 -9 / 9^(3/2) -9/27 -1/3 yes D
*November 24, 2014*

**ratios and proportional relationships**

15/100 = 75/w so w = 7500/15
*November 24, 2014*

**trig**

1. cos x = 1/2 x = 60 or x = -60 which is 300 in degrees or x = pi/3 or x = 2pi-pi/3 = 5 pi/3 in radians
*November 24, 2014*

**physics**

period = T = 18.5/23 seconds speed = 168 centi meters/ 20.21 seconds distance = speed * time = (168/20.21)(18.5/23)
*November 24, 2014*

**Chemistry**

If it weighs any number of grams it has millions of atoms even if it is URANIUM!!!!! 6.02 * 10^23 molecules/mol Avagadro's constant 7 C = 84 g/mol 8 H = 8 g/mol so 92 g/mol (74.5/92) * 6*10^23 = 4.86 *10^23 MOLECULES 7 times that many C atoms 8 imes that many H atoms
*November 24, 2014*

**science**

CO2 has just as many O atoms as O2 so the same number of mols
*November 24, 2014*

**PLEASE HELP CHEMISTRY**

Ag = 108 g/mol N =14 g/mol O3 = 3*16 = 48 g/mol so AgNO3 = 170 g/mol of which 108 is silver (108/170)(85) = 54, close enough
*November 24, 2014*

**Calculus**

y = f(x) dy/dx = f'(x) = y' first derivative d^2y/dx^2 = f''(x) = y'' second derivative
*November 24, 2014*

**Algebra**

cost = 30,000 + 42.25 x so 64.95 x = 30,000 + 42.25 x profit = (64.95-421.25)x - 30,000 = 100,000
*November 24, 2014*

**Chemistry**

Hey, Li has ONE valence electron I think you mean Li2SO4 6.02 * 10^23 molecules/mol so we have 6.78/6.02 = 1.13 mols of Li2SO4 which mean 2.26 mols of Li+ ions then we have 1.13 mols of SO4-- ions so 2.26 + 1.13 = 3.39 mols of ions in all
*November 24, 2014*

**chemistry physics**

You are welcome
*November 24, 2014*

**chemistry physics**

You get back 40 (((miles / hr) meters) / second) = 17.8816 m2 / s2
*November 24, 2014*

**chemistry physics**

Use Google for those conversions type 40 miles/hr meters/second and click
*November 24, 2014*

**chemistry physics**

looks resonable
*November 24, 2014*

**chemistry physics**

I just sent you a link for these Doppler problems.
*November 24, 2014*

**Math Help!**

That is the way I would do it :)
*November 24, 2014*

**Math Help!**

or rather 100 x = 6 * 179,000 x = 6 * 1790 = 10,740
*November 24, 2014*

**Math Help!**

yes 100 x = 6 * 179,000 = 6 * 1790 = 10,740
*November 24, 2014*

**Math Help!**

I would write 6/100 = x /179,000
*November 24, 2014*

**Math Help!**

In real life I would not have done this as a proportion. I would have said .06 * 179,000 = 10,740
*November 24, 2014*

**Math Help!**

I would not have written it your way, but your arithmetic is strange and I can not see how you got the right answer. 107400/100 = 1074 not 10740 but 10740 is correct
*November 24, 2014*

**Math Help!**

6/100 = x /179,000 yes answer is 10,740 but you method is suspect
*November 24, 2014*

**Chemistry Physics**

yes, just did this a minute ago http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html#c4
*November 24, 2014*

**math**

7 + x 2 + x 7+x = 2 (2+x) 7 + x = 4 + 2 x x = 3
*November 24, 2014*

**Math Help!**

.3 * 60 = 18
*November 24, 2014*

**math physics**

yes http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html#c4
*November 24, 2014*

**calculus**

You do not really need calculus. It is a parabola, find the vertex y=(x^2)-6x+10 x^2 - 6 x = y - 10 x^2 - 6 x - 9 = y-19 (x-3)^2 = (y-19) vertex at (3 , 19)
*November 24, 2014*

**calculus**

Oh y' = 2x-6 for 0, x = 3
*November 24, 2014*

**calculus**

Huh? There are values of y for each of those values of x at x = -3 y = 9 + 18 + 10 = 37 at x = 3 y = 9 -18 + 10 = 1 what is the question?
*November 24, 2014*

**Math Help!**

well, it better come out 35 :) either A or B will work. They are really the same. A is the one I would use
*November 24, 2014*

**Physics**

Yes, but multiply that by .25 to get the friction force 750 - 250 * 9.8 * .25 = 250 a 750 - 612 = 250 a
*November 24, 2014*

**Math Help!**

.8 * 20 = 16
*November 24, 2014*

**Math**

r = 6 base area = pi (36) height = sqrt (100 -36) = 8 vol = (1/3) pi (36)(8)
*November 24, 2014*

**algebra**

.14 s + .07 c = .13 (280) and s + c = 280
*November 24, 2014*

**physics**

By the way it will happen twice. The first time is when A catches up with B and is moving faster at 6 m/s the second time is as A is ahead of B but B is still accelerating and will catch up with A You want the first time I suspect. so use the - sign answer.
*November 24, 2014*

**physics**

distance A goes = 50 + distance B goes 6 t = 50 + B B = (1/2) a t^2 = .15 t^2 so 6 t = 50 + .15 t^2 .15 t^2 - 6 t + 50 = 0 does that have a positive real root? b^2-4ac = 36 - 30 = 6 sure enough so there is a time when they hit t = [ 6 +/- sqrt 6 ] /.3
*November 24, 2014*

**math**

Volume of anything with a pointy top and straight sides = (1/3) base area * height 9.00 meters square or 81 meters square, proofread !!! m is not m^2 if side is 3 then half side is 1.5 so it goes up h with base 1.5 and hypotenuse 1.76 h^2 + 1.5^2 = 1.76^2
*November 24, 2014*

**Math Physics**

yes 3 * 10^=6
*November 24, 2014*

**physics**

I just gave you a recipe below
*November 24, 2014*

**College Physics**

I am not going to do this for you. If you really do not know how to go about it here is a recipe: 1. convert 450 food calories which is 450,000 physics calories to joules. http://www.rapidtables.com/convert/energy/Calorie_to_Joule.htm Joules/second sleeping = 64.6 64.6 Joules/...
*November 24, 2014*

**algebra 2**

If you mean sqrt (a/b) / sqrt (a^2/b^2) = sqrt (a/b) / (a/b) = (b/a) sqrt (a/b) = sqrt (b/a)
*November 24, 2014*

**Problem Solving**

8 * 75 = 4 * 150 = 2 * 300 = 600
*November 24, 2014*

**Brief Calculus**

both odd functions through origin same area both sides of y axis 2 times integral 0 to 1 of xdx - x^3dx = 2(1^2/2 - 1^4/4) = 2(1/2-1/4) = 2(1/4) =1/2
*November 24, 2014*

**Uniform Motion**

downstream = 15/3 = 5 km/hr upstream = 15/5 = 3 km/hr so v+c = 5 v-c = 3 ---------- subtract 0 +2c = 2 c = 1 km/hr
*November 24, 2014*

**Chemistry Physics**

see below 10^8 /10^6 = 10^2 so 6
*November 24, 2014*

**Math Physics**

You are welcome.
*November 24, 2014*

**Math Physics**

distance = speed * time = speed/frequency so that part is fine but (3/50)(10^8/10^6) = (6/100)(10^2) = 6 meters
*November 24, 2014*

**Physics**

let x = a sin (w t + p) then dx/dt = v = a w cos (w t + p) d^2x/dt^2 = A = -a w^2 sin (wt+p)=-w^2 x then F = mA -kx = m (- w^2 x) w^2 = k/m w = sqrt (k/m) when w t = 2 pi, we have period T so w/(2 pi) = 1/T = f the frequency so f = (1/2pi) sqrt(k/m) so A. f = (1/2pi)sqrt (...
*November 24, 2014*

**Social Studies**

China is over 90% Han. As for the rest, think !
*November 24, 2014*

**Algebra Huh ?**

Please check for typos. If you have a line y = m x + b then the line perpendicular to that will have slope = -1/m so y = -(1/m) x + c and they cross at right angles
*November 24, 2014*

**physics**

I do not know what this means. Nothing is ever perfect, but after rounding off experimental results such as 1.51 and 1.52 to two significant figures they are both 1.5 so the difference would be zero (0.0) although it is not zero in real life.
*November 24, 2014*

**Physics**

Well, you need to ignore friction. If so then: Initial velocity up = Vi v at top = 0 so 0 = Vi - 9.8 t where t it time at top so t at top = Vi/9.8 so Vi = 9.8 t total time in air = 2 t = Vi/4.9 You measured 2 t evidently so divide your total time by 2 to get rise time t height...
*November 24, 2014*

**physics**

180 km/hr = (180/3.6) m/s so to run 1000 meters takes 1000 (3.6/180) = 20 seconds energy used = 560,000 Joules/s * 20 sec = 11,200,000 Joules 165 km/hr = (165/3.6) m/s 1000 (3.6/165) = 21.8 seconds energy used = (783) *21.8 = 17,083 Joules so 11,200,000 - 17,083 I do not ...
*November 24, 2014*

**math**

q = 2 d .25 q + .10 d = 3.6 .25(2 d) + .1 d = 3.6 .6 d = 3.6 6 d = 36 d = 6 so q = 12
*November 24, 2014*

**physics**

work = force * distance in direction of force so power = work/time = force * speed in direction of force 2.5 * 10^7 Watts This ignores and interaction between the flow around the plane in free stream and the propulsion system.
*November 24, 2014*

**Physics**

u = 40 forever so x = 40 t Vi = 0 v down = 0 + 9.8 t = 9.8 t z = height at top - 4.9 t^2
*November 24, 2014*

**science**

Vi = v sin 27.7 0 = Vi - 9.8 t t = v sin 27.7 /9.8 that is time to the top total time in air = 2 t = 2 v sin 27.7/9.8 u = v cos 27.7 d = (v cos 27.7)(2 v sin 27.7 /9.8) d = (2 v^2/9.8) cos 27.7 sin 27.7 but 2 cosA sinA = sin 2A d = (v^2/9.8) sin (55.4) either do d for v = 7.6 ...
*November 23, 2014*

**add error**

24 c = 360 c = 15 t = 20
*November 23, 2014*

**algebra**

t = c + 5 8 t + 16 c = 400 ================= 8 t - 8 c = 40 8 t + 16c = 400 ----------------- subtract -8 c = -360 c = 45 etc
*November 23, 2014*

**physics**

nope the frequency does not change. The speed of the wave changes so the length changes. There is no place to store leftover crests and troughs if you try to get five out one end per second while putting four in the other end
*November 23, 2014*

**physics**

Pe1 = 1.5 * g * h Pe2 = 4.5 * g * h so Pe2 = (4.5/1.5) (7)
*November 23, 2014*

**PLEASE HELP PHYSICS**

I think 1 is true. I can change the frequency of the sound waves from my lips by changing the frequency I generate them at. In fact the wave frequency is the generator frequency.
*November 23, 2014*

**PLEASE HELP PHYSICS**

1. sure, whistle different notes. 2. I agree false. 3. I agree true.
*November 23, 2014*

**Physics**

The paper runs out when the child has run 40 meters. The rest is irrelevant. 40 = (1/2) at^2 80 = .35 t^2 t = sqrt (80/.35)
*November 23, 2014*

**Trig- math**

You are welcome.
*November 23, 2014*

**Trig- math**

http://www.mathopenref.com/heronsformula.html
*November 23, 2014*

**physics**

work in = drag force * length of ramp (in other words the work done by the person dragging) gain in PE = m g h = 65 * 9.8 * 2 efficiency = 100(gain in PE/work in)
*November 23, 2014*

**trig**

need to know mu, friction coef if there is no friction, let mu = 0 F - mu (70) cos A = (70) sin A if mu is zero then F = 90 sin A so sin A = 36/90
*November 23, 2014*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html
*November 23, 2014*

**Physics**

so what is the question?
*November 23, 2014*

**science**

well, baking soda and vinegar make models go fast. Vinegar is acid, baking soda is what you want. Lye soap is pretty caustic. Bleach maybe Borax. Mostly stuff you use for cleaning.
*November 23, 2014*

**Math**

60 - (-29) = 60 + 29 = 89
*November 23, 2014*

**Physics**

well, not quite the last part after you find t, the time, is d = (1/2) a t^2
*November 23, 2014*

**Physics**

Now that is quite enough. You are asking really the same question over and over again.
*November 23, 2014*

**Physics**

same as your last question 0 = 215/3.6 + a (2.7) a will be negative because braking
*November 23, 2014*

**Physics**

90 km/hr = (90*1000/3,600) m/s v = 0 + a t 90/3.6 = a (10) a = 9/3.6 m/s^2
*November 23, 2014*

**math**

9 + (9+.5 b) + b but b = (9 + 9 + .5 b = 18+.5 b .5 b = 18 b = 36 so 18 + 18 + 36 so answer: 72 or six feet check head = 9 body = 36 tail = 36-9 = 27 9 + 36 + 27 = 72 sure enough
*November 23, 2014*

**physics**

normal force = 400 g cos 35 friction force up slope = .6 (400 g) cos 35 weight component down slope = 400 g sin 35 400 a = 400 g sin 35 - .6 (400 g cos 35) a = g (sin 35 - .6 cos 35) = .082 g
*November 23, 2014*

**Algebra**

first 10,000 for 3 years 10,000 (1.10)^3 then second year deposit 10,000 (1.10)^2 then 10,000 (1.10) or 10,000 (1.1^3 + 1.1^2 + 1.1)
*November 21, 2014*

**Physics**

You are welcome.
*November 21, 2014*

**Physics**

I w before = I w after by conservation of angular momentum 3.1 * 8 - 10.2 * I = -2.6 (3.1+I)
*November 21, 2014*

**ET1210- Dc/Ac Circuits**

p = V i but i = V/r so p = V^2/R and thus R = V^2/p
*November 21, 2014*

**ET1210-Dc/Ac Circuits**

the voltage drops equally through each resistor if in series (same current through each and V=iR) so V/number
*November 21, 2014*

**Math**

I do not know. Make sure you have no typos. I think it was meant to be easier.
*November 21, 2014*

**Math**

81 = 3^4 so 3^4x = 64 27 = 3^3 so we want 3^(3x+3) 3^4x = 2^6 4x log 3 = 6 log 2 x = 6 log2 /4 log 3 = 1.5 log2/log3 = whatever, calculator so y = 3^(3x+3) log y = (3x+3) log 3 find log y take 10^log y = y
*November 21, 2014*

**Physics**

it has not only (1/2) m v^2 but also (1/2) I w^2 where w = angular velocity if it does not slip then w = v/r I = (2/3) m r^2 for thin spherical shell so ke = (1/2) m v^2 + (1/2) m (2/3) r^2 v^2/r^2 mgh = (1/2) m ( v^2 + 2/3 v^2) h = (1/2g) (5/3) (3.83)^2
*November 21, 2014*