Saturday

November 22, 2014

November 22, 2014

Total # Posts: 19,402

**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*

**science**

Density is mass/unit volume Inertia is resistance to change in motion mass is a scalar measure of how many neutrons and protons you have degrees is either a measure of temperature or angle or something you get when you graduate
*November 21, 2014*

**Math**

a (2)^r = 1 so a = 1/2^r a (32)^r = 4 but 32 = 2^5 a (2)^5r = 4 2^5r / 2^r = 4 2^4r = 4 so 4 r = 2 r = 1/2 check a = 1/sqrt 2 a sqrt(32) = sqrt 32/sqrt 2 = 4 sqrt 2/sqrt 2 = 4 sure enough
*November 21, 2014*

**Math - makes no sense**

You either have a typo or your text was written in some other universe. r ? what r? from your first constraint a = 1/4 that does not work for your second constraint
*November 21, 2014*

**Algebra Help please!**

No, do P2 now P2 = 6,000 (1.03)^16 then find P2 -P1
*November 21, 2014*

**s.s**

cold and hungry committed to General Washington and the cause of independence
*November 21, 2014*

**Physics**

20 radians = (1/2)alpha t^2 20 = (a/2) (8.7)^2 a = 40/8.7^2 = .528 v = a t = .528 * 8.7 = 4.60 rad/s yes Ac = v^2/r = omega^2 r = 8.7^2 (.25)
*November 21, 2014*

**algebra 2**

6 x^2 - x - 1 = 0 x = {1 +/- sqrt (1 +24) } /12 (1 +/-5) /12 1/2 or -1/3
*November 21, 2014*

**science**

water is about 1000 kg/m^3 we have 140 m^3 of water so 140,000 kg of water the force of gravity on that is 9.81 * 140,000 = 1,373,400 Newton's third law says the bottom of the pool has to push up with that same force 1,373,400 Newtons pressure = force/area = 1,373,400/(10*...
*November 21, 2014*

**Math**

4/3 = 8/6 7/2 = 21/6
*November 21, 2014*

**Physics**

It goes up, then down for 1.05 s do the vertical problem Hi = 2 final h = 0 h = Hi + Vi t - 4.9 t^2 0 = 2 + 1.05 Vi - 4.9 (1.05)^2 -2 + 5.4 = 1.05 Vi Vi = 3.24 m/s initial speed up Now the horizontal problem max speed * sin 10 = 3.24 so speed = 18.7 m/s so u = 18.7 cos 10 = 18...
*November 21, 2014*

**Math**

interest = 5 * 10,000 * .07 = 3500 interest = 10,000 * 1.06^5 - 10,000 = 3382.26 subtract
*November 21, 2014*

**Physics**

well, then you have your answer F = (1/2) 217 (.625)^2 / .195
*November 21, 2014*

**Physics**

I = (1/2)m r^2 F (.195) = I alpha since you did not say what the angular acceleration alpha is, I can not do anything more for you
*November 21, 2014*

**physics**

impulse = change in momentum = 9*11 + 9*8 kg m/s
*November 21, 2014*

**Chemistry**

H2O = 18 g/mol, 16 of which is O so we have in the water (16/18)(10) = 8.89 kg of O that is 8890 grams or 556 mols of O or 278 mols of O2 in the water how many mols of O2 did we end up with in the air T = 273+25 = 298 do P V = n r T, solve for n or know that 1 mol is 22.4 ...
*November 21, 2014*

**physics**

.001 * .065 Nm
*November 21, 2014*

**mixture problems**

fat = f .45 f + .03 (500) = .05 (500+f) or .40 f = .02(500)
*November 21, 2014*

**Algebra**

25 x = y - 500 so x = (1/25)y - 20 y is already solved for
*November 21, 2014*

**Math Help!!!**

x = xi + delta x -2+1 = -1 y = yi + delta y -5+3 = -2 (-1,-2)
*November 21, 2014*

**Math Help!!!**

5 - no idea 8 - no idea 7 - NO - y is the same, x changes sign so (-8,-10) the first on the list
*November 21, 2014*

**physics**

by conservation of momentum 2.8 * speed of rifle back = .00984*726 solve for speed of rifle back, Vr Ke = (1/2)(2.8)(Vr)^2 + (1/2)(.00984)(726)^2
*November 21, 2014*

**phisics**

vertical problem first Vi = 551 sin 12 v = Vi - 9.8 t v = 0 at top so t = Vi/9.8 at top total time in air = 2 t = Vi/4.9 now horizontal: u = 551 cos 12 distance = u (Vi/4.9)
*November 21, 2014*

**Math**

5 times Greg's age is 55, 5 G = 55 so Gregg's age is 55/5 or G = 55/5 which is 11 11 + 11 + 11 + 11 + 11 = 55
*November 21, 2014*

**math**

do it this way (distributive property of multipication): = -q(q^2-2) + 3(q^2-2) then combine like terms or use FOIL if you happen to know the system. It is really the same thing.
*November 21, 2014*

**math**

-1 (p+5)(p-5) in general a^2-b^2 = (a+b)(a-b) so this is -1(p^2-25) which is 25-p^2 or use distributive property as I did in your other problem
*November 21, 2014*

**Math**

You left t out ! max at 15 min min at 15+14 = 29 so 14 min from sin = +1 to sin = -1 that is half a period so T = 28 min 2pi t/T = 2 pi at t=T we disagree about all this so pi t/14 is 2 pi when t = T = 28 range from max to min = 2 A = 125-99 = 26 so A = 13 (check with you :) ...
*November 21, 2014*

**Physics**

I * omega = the same I gets smaller so omega gets bigger
*November 21, 2014*

**math**

v+c=23 v-c=11 ========add 2 v = 34 v = 17 mph
*November 21, 2014*

**physics**

a = -7 miles/s^2 I assume you mean but your units look screwy. Perhaps you mean -7 miles per hour/second and I will do that alternative at the end but please read what you wrote in the future before posting. Vi = 40/3600 miles/second v = Vi - 7 t 0 = 40/3600 - 7 t t = .0016 ...
*November 20, 2014*

**math 3**

z = (x-mean)/sigma so x = mean + z*sigma 1.25*7 = 8.75 cents 1.25 + .0875 = $1.34
*November 20, 2014*

**algebra**

I need 2 mol of H2SO4 so I need 2/10.01 dm^3 of concentrate = .1998 dm^3 of concentrate
*November 20, 2014*

**physics**

.045 kg / (25 *10^-6 m^3) = 1800 kg/m^3 1.8 times density of water ? Are you sure data is correct? 25 cm^3 of water has mass of 25 grams
*November 20, 2014*

**math**

210 = (h+3) (L +2) = h L + 3 L + 2 h + 6 or h L + 3 L + 2 h = 204 L(h+3) = 204-2h L = (204-2h)/(h+3) A = L h A = h(204-2h)/(h+3) for max dA/dh = 0 = h[(h+3)(-2) -204+2h]/(h+3)^2 +(204-2h)/(h+3) =h[-2h-6-204+2h]/(h+3)^2 +(204-2h)/(h+3) =-210 h/(h+3)^2 + (204-h)(h+3)/(h+3)^2 = ...
*November 20, 2014*

**physics - need radius**

need radius of wire, not just current R = V/i = .0320/1.35 = .0237 Ohms = resistivity * Length/area so resistivity = .0237 * pi r^2 /2.8 table of conductivity and resistivity here http://hyperphysics.phy-astr.gsu.edu/hbase/tables/rstiv.html
*November 20, 2014*

**math**

y = k sqrt x 6 = k (2) k = 3 y = 3 sqt x y = 3 (5) y = 15
*November 20, 2014*

**Math**

17,000 + 3 $/gal * (1/22) gal/mi * Mi = 23,000 + 3 * (1/50) * Mi
*November 20, 2014*

**Algebra2**

log2 [(x+8)/5] = 4 (x+8)/5 = 2^4 = 16 x+8 = 80 x = 72
*November 20, 2014*

**math please help**

no, see my reply below.
*November 20, 2014*

**thermodynamics**

(1/2)m v^2 = 625(1600) Joules divide by 1000 for kJ that is also the work to stop it in kJ
*November 20, 2014*

**math thanks for your help**

3 (-2)^3 +5(-2) - 6 every term is negative for x = -3 so no way
*November 20, 2014*

**science**

P V = n R T same pressure ? V/T = n R/P = consatnt V1/T1 = V2/T2 6/(2T2) = V2/T2 V2 = 3 in^3
*November 18, 2014*

**geometric progression**

a , ar , ar^2 , ar^3 , ar^(n-1) ar^2 = 10 ar^5 = 80 ar^5 / ar^2 = 8 r^3 = 8 r = 2 ====================================== now you do the second one.
*November 18, 2014*

**physics**

d = (1/2)(9.8)t^2 10 = 4.9 t^2 t = 1.43 seconds falling v = a t v = 9.8 (1.43) = 14 m/s , yes right Your way is fine. I just cheated to get it faster.
*November 18, 2014*

**physics**

P = m V m (2) = 100 m = 50 kg
*November 18, 2014*

**Algebra**

power = V i = V( V/R) = V^2/R sure enough to triple the power at the same V, use 1/3 the resistance R This can be done easily and very understandably by running three of the original Rs in parallel, like turning three stove burners on instead of one.
*November 18, 2014*

**Algebra**

Yes, it makes sense, 7 times further is 1/49 th of brightness
*November 18, 2014*

**Algebra**

7*7 = 49 which is about 50
*November 18, 2014*

**Math**

12 - 18 = -6
*November 18, 2014*

**Math**

2 is D.
*November 18, 2014*

**algebra 1**

-64 = -4*-4*-4 = -4^3 (x^8)^1/3 = x^(8/3) (x^5)^(1/3) = x^(5/3 -4 x^(8/3) y^(5/3)
*November 18, 2014*

**Physics**

sin^-1 (1/1.49)
*November 18, 2014*

**Physics**

NET force = 2100 - 1800 !!!!!!!
*November 17, 2014*

**Physics**

1. a = F/m = (2100-1800)/1200 2. d = (1/2) a t^2 = 50 a 3. v = a t = 10 a
*November 17, 2014*

**Algebra - quick question**

if y = a e^kx then dy/dx = = k a e^kx = k y if it is discrete yn+1 = yn + k yn = (1+k) yn hen yn+1 - yn = k yn in other words the change = constant times present value
*November 17, 2014*

**math**

t = FINAL tuna e/(t-15) = 2/3 e/t = 1/3 so finally t = 3 e e/ (3e -15) = 2/3 3 e = 6 e - 30 e = 10 t = 3 t = 30
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

if interest rate is 2% per year compounded yearly then Yn+1 = Yn + .02 Yn = Yn (1.02) and in general Y = Yinitial * (1.02)^n
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

The important thing here is that the rate of change is proportional to your present value, so the change keeps changing. The most common example is compound interest
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

I believe 1 and 6 are the same question asked different ways.
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

Yes, it told you to keep doing it until you get to 11.04, that was after 5 days (I cheated and took the log of both sides so solve directly)
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

10.82 fifth day 10.82*1.02 = 11.04 done
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

I guess I did not explain very well in the first question for example it asks you to plug and chug from 0 to 11.04 I did not bother but first day 10*1.02 = 10.2 second day 10.2 * 1.02 = 10.4 third day 10.4 * 1.02 = 10.61 fourth day 10.61 * 1.02 = etc until you get to 11.04
*November 17, 2014*

**Algebra - Can you PLEASE check - I**

11.04 = 10 (1.02)^n I am not going to try lots of days, boring log 11.04 = log 10 + n log 1.02 4.996 days so five days 2. n>0 and <the life of the plant 3. when n = 0, height = 10 4. the height of the plant when we bought it 5. F(n+1) = F(n) * 1.02 6. calculate F(1) = 10...
*November 17, 2014*

**Science 8**

volume = mass/density the volume of this thing =28.0-15.6 = 12.4 mL so the density = 101.7 g/12.4 mL = 8.2 g/mL Is that the density of copper ?
*November 17, 2014*

**Algebra - can you PLEASE double check my work?**

sqrt 2 * sqrt 2 = 2 = 2/1 you can not write sqrt 2 as a ratio of integers but you certainly can write 2 as a ratio and 2 is sqrt 2 * sqrt 2 by definition However do not try to write 1.41 etc * 1.41 etc as a ratio
*November 17, 2014*

**Algebra - can you PLEASE double check my work?**

1 and 2 look fine There is nothing you can multiply sqrt 2 by to get a rational number but sqrt 2 or a multiple thereof L * W yes 4*2 x = 8 x as we said above if you multiply sqrt 2 by sqrt 2 it comes out a perfectly rational 2 HOWEVER, you better do it symbolically with sqrt ...
*November 17, 2014*

**math (stats)**

Just go here http://davidmlane.com/hyperstat/z_table.html
*November 17, 2014*

**physics**

1.7 x = 26*9.81*.75
*November 17, 2014*

**math**

sorry h/33 = 6/4 = height/shadow
*November 17, 2014*

**math**

33/h = 6/4
*November 17, 2014*

**Algebra**

and (c) is 2800 but (b) you actually have to calculate first you do not mean what you typed you mean P(t) = 2800/ ( 1 + 6e^−0.05t ) now it t = 12 months p = 2800 / ( 1 + 6 /e^.6) = 2800 / 4.29 = 652 USE PARENTHESES for denominators with multiple terms
*November 17, 2014*

**Trig**

tan 65 = h/16 so h = 16 tan 65
*November 17, 2014*

**Physics**

I did this all out for you earlier. Scroll down.
*November 17, 2014*

**Physics**

d = 4 /(.00289 - .000667) = 4/.0022 = 1818 m
*November 17, 2014*

**Physics**

= 1818 m
*November 17, 2014*

**NO!!!**

d = 4 /(1/Va -1/Vw)
*November 17, 2014*

**Physics**

but all it asked for was d = 1380 meters
*November 17, 2014*

**math**

oh, if you graphed carefully, no need to do (31.11,31.11) because it is above others. however the (70,0) point where b hits the x axis should be checked even if you can see it is not going to be max.
*November 17, 2014*

**LINEAR PROGRAMMING**

orange crates = x grapefruit crates = y constraints a)4x+6y</= 300 b)60 x + 75 y</= 4200 c)y</= x maximize p = 2.5 x + 4 y graph those constraint lines and mark intersections a hits c at (30,30) b hits c at (31.11, 31.11) a hits b at (45,20) our region is between the ...
*November 17, 2014*

**algebra**

note for t = 400, there are about 2800 http://www.wolframalpha.com/input/?i=plot++2800%2F%281%2B6%28e^-%280.05t%29%29+%29++for+t+%3D+400
*November 17, 2014*

**bad link copy**

http://www.wolframalpha.com/input/?i=plot++2800%2F%281%2B6%28e^-%280.05t%29%29+%29
*November 17, 2014*

**algebra**

If so try: http://www.wolframalpha.com/input/?i=plot++2800%2F%281%2B6%28e^-0.05t%29+%29 when t = 0, e^0 = 1 so 2800/7 when t-->oo 2800/( 1 +6/big) = 2800
*November 17, 2014*

**typo?**

Do you mean: P(t) = 2800/(1+6e^-0.05t) ????
*November 17, 2014*

**math**

I already gave a link to communative property explanation down below
*November 17, 2014*

**Math**

9-5 = 4 along sides for entire length of floor so 4 *16 for sides ends are 16-12 = 4 by 5 = 20 4*16 + 20 = 84
*November 17, 2014*

**math**

ah, here we go: http://coolmath.com/prealgebra/06-properties/01-properties-commutative-addition-01.htm
*November 17, 2014*

**math**

if 7 cows + 9 cows fill a field then 9 cows + how many cows fill the field?
*November 17, 2014*

**math**

make a guess and I will come back and look
*November 17, 2014*

**Math**

You are welcome.
*November 17, 2014*

**Math**

tulips = t roses = 4 t t + 4 t = 40 5 t = 40 t = 8 4 t = 32
*November 17, 2014*

**calculus**

x y = 147 so x = 147/y x + 3 y = a 147/y + 3 y = a da/dy = 0 for max or min = 3 -147/y^2 y^2 = 147/3 = 49 y = 7 x = 147/7 = 21 so x = 21 and y = 7
*November 17, 2014*

**Physics**

d = 4 /(.00289 - .000667) = 4/.0022 = 1818 m
*November 17, 2014*

**NO!!!!@**

d = 4 /(1/Va -1/Vw)
*November 17, 2014*

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