Tuesday

February 21, 2017
Total # Posts: 29,370

**Science Physics**

There is one thing you can really count on, Newton's First Law. If there is no external force on a system, the momentum remains CONSTANT Momentum before = Momentum after. If I could underline that PERIOD I would do so. You can not count on mechanical energy being the same ...

*December 5, 2016*

**Math**

w + L = 108 L = w + 30 so w + w + 30 = 108

*December 4, 2016*

**physics**

F = m a F = 3kg* 5m/s^2 = 15 Newtons a = F/m a = 15N/12.2kg a = 1.23 m/s^2

*December 4, 2016*

**statistics**

http://davidmlane.com/hyperstat/z_table.html

*December 4, 2016*

**math double check please**

yes, two 2s and a 3 yes, 420 * 3

*December 4, 2016*

**pre calculus**

http://www.jiskha.com/display.cgi?id=1480860809

*December 4, 2016*

**Calculus**

see the rope and the boat problem below.

*December 4, 2016*

**Calculus**

h height above bow (constant=7) y hor distance to bow (25 at moment) x = our rope length x^2 = h^2 + y^2 2 x dx = 0 + 2ydy dy/dx = x/y dy/dt = dy/dx dx/dt = 2 (x/y) x = sqrt (7^2 + 25^2) = 26 so dy/dt = 2 (26/25) = 2.08 m/s

*December 4, 2016*

**Calculus**

hint dA = 2 pi r dr so dA/dr = 2 pi r and dA/dt = dA/dr * dr/dt

*December 4, 2016*

**PHYSICS (REALLY DIFFICULT PLEASE HELP)**

18+273 = 291 K 0 + 273 = 273 K P V = n R T 103 * 23 = n R *291 n R = 103*23/291 same n R later 101 V = n R 273 V = n R (273/101cm^3) V = (103*23/291)(273/101) cm^3 22 cm^3 = .0022 Liters = 22*10^-6m^3 ================================== P V = n R T 101325 (22.4 liters)(1m^3/...

*December 4, 2016*

**Sequence and serice**

54/100 or 27/50 a rational number is any one that can be expressed as a ratio of whole numbers.

*December 4, 2016*

**maths**

2n + 24/6 = 25/6 n = 1/12

*December 4, 2016*

**pre calculus**

2 1 2 4 2 2 0 5 2-1 6 2 1 0 2 3/2 0 1-2 1 0 0 0 0 (3/2, 1, 0)

*December 4, 2016*

**pre calculus**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

*December 4, 2016*

**Maths**

The diagonal sqrt(24^2 + 18^2)

*December 4, 2016*

**Where are you stuck?**

So what did you do?

*December 3, 2016*

**Math**

(1/2)(40 + 3/8) = 20 + 3/16 20 3/16

*December 3, 2016*

**Math**

2/12 = 1/6 24 * 1/6 = 4 or 12/24 = 2/x 12 x = 48 x = 4 or the original width was twice the length twice 2 is 4

*December 3, 2016*

**Math**

Then count the number of one inch by one inch square boxes. You will get 50 of them, 5 times 10 :)

*December 3, 2016*

**Math**

Because to find the area of a rectangle you multiply the length by the width. To figure out why, draw a picture 10 inches by 5 inches and divide it up into columns one inch wide and rows inch high.

*December 3, 2016*

**Math**

yes, multiply

*December 3, 2016*

**CSC**

(2s-44)+(s+22)+ s = 5858 4 s -22 = 5858 4 s = 5880 s = 1470 etc

*December 3, 2016*

**Physics**

vertical problem Vi = 25.8 sin 20 = 8.824 m/s v = Vi - 9.81 t at top v = 0 t = 8.824/9.81 = .900 seconds at top (therefore 1.8 seconds in air by the way) h = Vi t - (9.81/2) t^2 = 8.824(.9) - 4.9(.81) = 7.94 - 3.97 = 3.97 meters high horizontal problem u = 25.8 cos 20 = 24.2 ...

*December 3, 2016*

**Math**

multiplying by 5/2 should not give the same answer as multiplying by 2/5(which is dividing by 5/2)

*December 3, 2016*

**Math**

21 7/8 * 2 1/2 one way is to use distributive property (21 + 7/8)(2 + 1/2) =(2 + 1/2)(21) +(2 + 1/2)(7/8) = 42 + 21/2 + 7/4 + 7/16 = 42 + 168/16 + 28/16 + 7/16 = 42 + 203/16 = 42 + 12 + 11/16 = 54 11/16

*December 3, 2016*

**Physics**

yes,your table is for a = dv/dt = 4 so dv = 4 * dt dv/dt = a = 4 v = a t = 4 t x = (1/2) a t^2 t a v x 0 4 0 0 1 4 4 2 2 4 8 8 3 4 12 18 4 4 16 32 5 4 20 50 It is that v column you want, how far it moves PER SECOND not how far it moved total.

*December 3, 2016*

**Physics**

so dx/dt = a t dx = a t dt at t = 0, dx = 0 at t = 1, dx = a at t = 2, dx = 2a at t = 3, dx = 3a at t = 4, dx = 4a etc in other words you are looking at v(t), the velocity, which is linear with time (the CHANGE in position, not the position) v = a t the POSITION itself will be...

*December 3, 2016*

**College Calc**

sqrt 576 = 24 24*4 = 96

*December 3, 2016*

**College Calc**

LOL,square min P, given A A = L w so L = A/w P =2L+2w P = 2A/w + 2 w 2 w^2 - w P = -2 A w^2 -(P/2)w = A w^2 -P/2 w + P^2/16 = -A + P^2/16 (w-P/4)^2 = -(1/16)(16A-P^2) vertex when w = P/4 (that is a square :) Area = P^2/16 = (P/4)^2 of course P given, max A A = L w P =2L+2w so ...

*December 3, 2016*

**Physics**

R is speed of rain r is angle of rain to vertical horizontal rain we see = Rsinr+bike speed vertical rain we see = R cos r case 1 hor = R sin r + 20 ver = R cos r tan 45 = (R sin r +20) /Rcos r case 2 tan 19deg48 min = (R sinr +12)/R cos r

*December 3, 2016*

**Algebra**

It is as if she got 89 on 5 of the 6 tests! (89*5 + x)/6

*December 3, 2016*

**Physics**

http://formulas.tutorvista.com/physics/doppler-shift-formula.html

*December 3, 2016*

**Physics**

As the ambulance approaches, the pedestrian will hear a higher frequency. As it recedes a lower frequency. Add the absolute values of the changes. For the formula, Google Doppler shift (classical not relativistic)

*December 3, 2016*

**chemistry**

4/2 = 2 mols of CO2 for every mol of C2H6 mol of C2H6 = 2*12+6 = 30 g mol of CO2 = 12+32 = 44 g 7500 * 2 * 44/30

*December 3, 2016*

**history knowledge**

I guess I would have to go along with that but wonder if it would have lasted if he had lived. The last few years of scooting around the Middle East and western Asia did not seem to be aimed at establishing any sort of permanent government but rather putting people in titular ...

*December 3, 2016*

**Physics**

Fup = m (9.81 + v^2/R) 2*265 = 30 (9.81+v^2/1.4) (b) 2*265 up assuming the seat has no mass :)

*December 3, 2016*

**Math**

55% is Cu and FE so 45% is zinc .45 *720 = 324 grams That is assuming this is a MATH, not a Chemistry problem. If it were Chemistry they might be looking at 1/4 of the molecules are Cu, not 1/4 of the mass.

*December 3, 2016*

**Math**

2^n

*December 2, 2016*

**Math**

5(.07)(8000)=2800

*December 2, 2016*

**Calculus**

Yes, of course -4-1 = -5 :)

*December 2, 2016*

**Calculus**

where do they hit? 4 x^2 = 45 - x^2 x^2 = 9 x = +/- 3 cylinder height = 45-x^2 - 4 x^2 = 45 - 5 x^2 cylinder thickness = dx cylinder circumference = 2 pi x so V=?[0,3]2 pi x(45-5x^2)dx

*December 2, 2016*

**So what?**

no question is asked.

*December 2, 2016*

**physics**

Vertical problem: at max height (half the trip) 600 = Vi t - .5*9.8 t^2 .5*9.8 t^2 - Vi t + 600 = 0 also v = 0 so 0 = Vi -gt t = Vi/g = Vi/9.8 so .5*9.8(Vi^2/9.8^2) - Vi^2/9.8 +600 = 0 600 = .5*VI^2/9.8 Vi = 108 m/s initial up speed t = rising time = 108/9.8 = 11.1 s total ...

*December 2, 2016*

**Finite Math**

A (1.0465)^6 = 15,000 A = 15,000/1.313516 = 11,419.73

*December 2, 2016*

**physics**

Ke = (1/2)(1260)(14.8^2) Joules go ahead and integrate m a dx if you want but energy is a lot easier.

*December 2, 2016*

**Physics**

total weight = (251+350)(9.81) + rhogas 9.81(4/3) pi (9.5)^3 where rhogas is the mass per unit volume of the gas in the balloon weight must = weight of air displaced = rhoout g (4/3)pi(9.5)^3 rho gas = kg/mol * n = .029 n where n is mols in PV =nRT T = 273 + T that we want rho...

*December 2, 2016*

**Pressure in Physics**

60 *9.81/10 N/m^2 or Pascals if you mean on the floor on earth and 10 is the floor area

*December 2, 2016*

**maths**

2 pi Ro = 44 solve for Ro then Ri = Ro - 2 so inner circumference = 2 pi Ri and Path area = pi(Ro^2-Ri^2)

*December 2, 2016*

**math**

16 = 4*4 12 =4*3 so 4*4*3 is LCM = 48 of each 3 packs HD 4 packs buns

*December 2, 2016*

**Physics**

google Bernoulli constant= v^2/2 + g z + p/rho in your units v in m/s p in Pascals(N/m^2) rho = 1000 kg/m^3 for water g about 9.8 v at bottom = 1.2 m/s v at top = 2 v at bottom =2.4 m/s z at top = z at bottom + .2 meters p/rho bottom =143000/1000 so 2.4^2/2 + 9.8(.2)+ 143 = 1....

*December 2, 2016*

**Math**

B yes C 128(0.5)^3 128*.125 = 16 yes D 128*.5^8 = 128* .00390525 = 0.5 YES !!!!!

*December 1, 2016*

**Math**

Gabby drove t-3 hours she drove 2 hours so t-3 = 2 and Ryan drove 5 hours D = Ryan speed * 5 D = Gabby speed * 2 so 5 R = 2 G but G = R+42 so 5 R = 2(R+42) 3 R = 84 R = 84/3 = 28 HUY - The DIFFERENCE is 42

*December 1, 2016*

**Calculus 1**

v = x^3 dv/dx = 3 x^2 dv/dt = dx/dt * dv/dx dv/dt = 4 * 3(121) cm^3/s

*December 1, 2016*

**math**

1000-850 = 150 interest 150 = 850 (.08) t

*December 1, 2016*

**Pre-Calculus**

satellite position is likely to be x, y , z of t :)

*November 30, 2016*

**science**

1. I disagree with you. People just assumed we were at the center. Partly religious 2. agree 3. agree 4. I agree with you. A and B are obvious. D is the sun and moon working together to produce spring tides when the moon is full and new and neap tides when the moon s half moon...

*November 30, 2016*

**Algebra**

v = dh/dt = 32 -32 t at top, v = 0 t = 1 h = 9+16 = 25 ====================== now with algebra 16 t^2 -32 t =9 - h complete square t^2 -2 t = (-1/16)(h - 9) t^2-2t+1 = (-1/16)(h - 9)+16/16 (t-1)^2 = -(1/16)( h-25) t = 1, h=25 same answer

*November 30, 2016*

**precalculus**

1 x +1 y = 2 1 x +1 y = 3 1 1 2 1 1 3 subtract top one from this 1 1 2 0 0 1 oh my! 0x+0y=1 ?

*November 30, 2016*

**College alegbra**

I assume this does not mean the perimeter but the total length of fencing. I assume x is the length and there are 3 y fences P = 2 x + 3 y x y = 1500 so y = 1500/x then P = 2 x + 4500/x x P = 2 x^2 + 4500 2 x^2 - xP = -4500 x^2 -xP/2 = -2250 x^2 -xP/2 + P^2/16 = -2250 + P^2/16...

*November 30, 2016*

**Calculus**

the function climbs uphill 15 from -3 to +12 in its jaunt of +5 from -1 to +4 that means that somewhere in between there the slope of the function is slope = 15/5 = 3 so at some x = c between x = -1 and x=+4slope = f'(c) = 3 so a)

*November 30, 2016*

**Physics**

(1/2) m v^2 = m g h or use Bernoulli (1/2) rho v^2 + rho g h + P = constant here P = 1 atm on top of the tank and at the outflow so the two ways are the same v = sqrt (2 g h ), just like the water fell amount that comes out per second = Q = Area*v = pi r^2 v = pi*10^-4 v so Q...

*November 30, 2016*

**Physics**

F/m = 2/60

*November 30, 2016*

**physics**

a = F/1 = i + 2 j -2 k v = Vi + a t x = Xi + Vi t + (1/2)a t^2 v at 5 = i+0j+2k + 5i +10j -10k = 6i + 10j - 8k x at 5, well assume start at (0,0,0) x = 0 +(i+0j+2k)5 +(1/2)(i + 2 j -2 k)25 = 5i+0j+10k+(1/2)(25i+50j-50k) =17.5 i +25 j -15 k check my arithmetic !

*November 30, 2016*

**Physics**

yes, both in watts or Joules/second

*November 30, 2016*

**Math**

same as when tan = -1 which is when theta = 90+45 =135 = 3 pi/4 or when theta = 360 - 45 = 315 = 7 pi/4

*November 30, 2016*

**Physics**

m v^2/r = 50 * 64 / 8 = 400 m/s^2

*November 30, 2016*

**Calculus AB**

-(x^4 - 5 x^2 + 6) / (x +3^.5) -(x^2-3)(x^2-2) /(x+3^.5) OH LOOK! -(x-3^.5)(x+3^.5)(x^2-2)/(x+3^.5) = -(x-3^.5)(x^2-2) when x is -3^.5 = -(-2*3^.5)(1) = 2 sqrt 3 Now there is a limit and I am at it without you doing some.

*November 30, 2016*

**Calculus**

is x^(1/5) defined and continuous in that interval? (-1)^(1/5) = -1 etc, seems ok how about arc cos x that looks fine x/(x-3) woukld blow up at x = 3, but we do not go there so it is ok but Oh my, sqrt(-1) is imaginary! and is called i for want of a real number to use. It is a...

*November 30, 2016*

**Integral Calculus**

Height = sin x radius = (3 pi/2 -x) = r so dr=-dx d volume = sin x (2 pi r (-dr)) = 2 pi sin x (3pi/2-x)dx =2 pi(3pi/2) sin x dx - 2pixsin x dx = -3 pi^2 cos x - 2 pi [sinx-xcosx] = [-3 pi^2+2pix]cos x -2 pi sin x at pi - at 0 sin is 0 at both so cos pi = -1 so - [-3 pi^2+2pi^...

*November 30, 2016*

**Algebra (Please Check My Answers)**

4. James attached a diagonal brace across a rectangular frame that measures 6 feet by 8 feet. What is the length of the diagonal brace? ~ 2 feet ~ 10 feet ~ 14 feet ~ 48 feet*** =================== 36+64 = 100 sqrt(100) = 10

*November 30, 2016*

**ss**

I am inclined to think you made the correct guess.

*November 30, 2016*

**Math**

Hmm be sure to put the numbers back in to check. a = 20 and c = 10 13 + 3 = 16

*November 30, 2016*

**Math**

a = 2 c a-7 + c-7 = 16 2 c + c - 14 = 16 3c = 30 c = 10

*November 30, 2016*

**Math**

x+35 + 5x-21 =180

*November 30, 2016*

**CHEM 1301**

H = 8/3 *12.2 = 32.5 12.2 + 32.5 = 44.7

*November 30, 2016*

**cal**

Good :)

*November 30, 2016*

**cal**

g = (x-1)/(2x+4) dg/dx = [(2x+4)-2(x-1)]/(2x+4)^2 at x = -1 dg/dx = m the slope = [(-2+4)-2(-2)]/(2)^2 = 6/4 = 3/2 and g = -2/2 = -1 so y = m x + b -1 = 3/2 (-1) + b b = 1/2 so y = (3/2) x + 1/2 or 2 y = 3 x + 1 check my arithmetic!

*November 30, 2016*

**cal typo ?**

g = x -.5 x + 4 did you mean x^2 maybe? or what?

*November 30, 2016*

**Algebra**

4 a + 5.5 c = 92 a + c = 20 4 a + 5.5 c = 92 4 a + 4 c = 80 ------------------subtract 0 + 1.5 c = 12 c = 8 etc

*November 30, 2016*

**math**

maximize .085 x + .068 y x+y <= 50,000 x>=6,000 x<=27,000 y<=34,650 x+y>=1 phony to fill fields I get $3859 at (27000, 23000) ==================== http://www.wolframalpha.com/widget/widgetPopup.jsp?p=v&id=1e692c6f72587b2cbd3e7be018fd8960&title=Linear%...

*November 30, 2016*

**cal**

You are welcome.

*November 30, 2016*

**cal**

3 x^2 dx + 3 y^2 dy = 3 x dy + 3 y dx (y^2 -x)dy = -(x^2-y)dx dy/dx = - (x^2-y)/(y^2-x)

*November 30, 2016*

**Math**

56 = 2 * 28 = 2*2*14 = 2*2*2*7 can not have more than one 2 2*7 = 14

*November 30, 2016*

**math**

2 by 3/2

*November 30, 2016*

**value**

4/5 = .8

*November 30, 2016*

**Math**

+ C :)

*November 30, 2016*

**Math**

x - 6?xdx/( x^2+1) let z = x^2+1 dz = 2 x dx so x dx = (1/2)dz then x - 6?(1/2)dz/z x - 3 ln z x - 3 ln(x^2+1)

*November 30, 2016*

**Math**

?(x^2-6x+1)/(x^2+1) dx =?(x^2+1)dx/( x^2+1)-6?xdx/( x^2+1) = ?dx - 6?xdx/( x^2+1)

*November 30, 2016*

**Portions and integers**

Zero just gives you an arbitrary point on the number line to measure the other two points from. The fact that it happens to be the melting point of ice is irrelevant to this problem. -89 is colder than -39 -89 is LEFT of -39 on our number line -89 < -39 how much colder is ...

*November 30, 2016*

**Not sure**

skin, hair, nails the only thing listed that is related is the hand.

*November 30, 2016*

**physics -- impossible**

if r is the radius above earth center the speed is totally impossible. I suspect a typo

*November 29, 2016*

**Huh initial height?**

If the velocity is only 3 m/s at the bottom, no way it will go up 10 meters. Typo? Did you leave out an initial height?

*November 29, 2016*

**math**

2 x/5 + 35000 = 3 x/4 35000 = 15x/20 - 8x/20 = 7 x/20 5000 = x/20 x = 100,000

*November 29, 2016*

**genetics - no idea**

not my thing - need biology teacher

*November 29, 2016*

**Physics**

LOL valve straight down is stable (pendulum) valve straight up is unstable (balancing pencil on nose) I = mr^2 = 1.005(.36) (about .36) for angle x in radians, restoring moment is about .005*9.81 x r = .003*9.81 x oh well call g = 10 instead of 9.81 = .03 x .03x = -I alpha = -...

*November 29, 2016*

**Algebra 2**

74-m = m/2 + 11 63 = 3 m/2 m = 63*2/3 = 42 74 - 42 = 32

*November 29, 2016*

**maths**

250 - 80 = 170 girls (170/250)100 = ?

*November 29, 2016*

**2**

You can not row cotton profitably everywhere. You need the right soil and water conditions and preferably a large area of flat land. Rice in particular uses very different soil conditions, like wet. Virginia climate was very good for tobacco as was Ky and Tenn.

*November 29, 2016*

**CHECK! LAST TIME MATH!**

100% - 20% = 80% or .8 100% - 10% = 90%

*November 29, 2016*