Saturday

February 6, 2016
Total # Posts: 25,133

**Calculus**

Steve gave you: let u = (x-r)^2 du = 2(x-r) dx dv = (1/r) e^(-x/r) dx v = e^(-x/r) CHECK SIGN ∫ u dv = uv - ∫ v du = (x-r)^2 e^(-x/r) - 2∫(x-r) e^(-x/r) dx now the second part of it. He said to do it again. u = x - r du = dx dv = e^-x/r v = -r e^-x/r -(x-r)e...
*November 28, 2015*

**Math**

17*10^6 * 6 = 102*10^6 = 1.02 * 10^8 meters earth to moon = 3.8 * 10^8 meters sorry :(
*November 28, 2015*

**Math**

base is 4 altitude is 8 x and y axes hit each other at the origin at 90 degrees (360/4) area is 16
*November 28, 2015*

**Math**

longest sides: 18/6 = 3 check 15/5 = 3 and 9/3 = 3 so 1/3
*November 28, 2015*

**math**

v = u + a t s = u t + (1/2) a t^2 10 = u(2)+ + (1/2) a (2)^2 or 10 = 2 u + 2 a 28 = u(4) + (1/2) a (16) or 28 = 4 u + 8 a 20 = 4 u + 4 a 28 = 4 u + 8 a --------------- 8 = 4 a etc
*November 28, 2015*

**Mathematics**

2 b + 2 (b+5) = 26
*November 28, 2015*

**maths**

5 w + w = 9 w = 9/6 = 3/2 = 1.5
*November 28, 2015*

**Math (prob)**

Assuming the tests are independent (different tests) the probability of passing each is .6. The probability of failing all three is .4^3 so the probability of passing at least one is 1 - .4^3
*November 28, 2015*

**chemistry**

how many mols of copper oxide (CuO) in 10 grams? Cu = 63.5 O = 16 CuO = 79.5 grams/mol so we have 10 grams / 79.5 g/mol = .126 mols of CuO same number of mols of Cu
*November 28, 2015*

**What does 60 degree NW mean ?**

North component = 90 cos (angle to y axis) West component = 200 + 90 cos (angle to -x axis) tan angle west of north =West component/North component magnitude = sqrt (North component^2 + West cvomponent^2)
*November 28, 2015*

**physical chemistry**

I assume you mean 1000 cm^3 which is in fact one liter. so we need .025 mol .025 * 58.5 g/mol = 1.46 grams
*November 28, 2015*

**thermodynamics**

Csilver * mass of silver * 75 = mass of ice * heat of fusion of water
*November 28, 2015*

**Phyics**

Box 1: m = 1.55 mg = 1.55*9.81 = 15.2 N friction force up slope = .226*15.2 cos 30 = 2.98 N up slope weight component down slope = 15.2 sin 30 = 7.6 N down slope T down slope (deal with after we find a Box2: m = 3.1 mg = 3.1*9.81 = 30.4 N friction force up slope = .113*30.4 ...
*November 26, 2015*

**Physics**

part (b) weight of block = normal force = m g = 3.5 * 9.81 = 34.3 Newtons maximum static friction force = .52*34.3 = 17.85 N That is the spring force you need 17.85 = k x 17.85 = 75 x x = .238 meters = 23.8 cm
*November 26, 2015*

**Trigonometry**

difference in height = 1450 tan 40 = 1450/x
*November 26, 2015*

**Chemistry**

P V = n R T Patm * 38.9 = n R T = constant = P *32.2 P = Patm (38.9/32.2)
*November 26, 2015*

**ENGLISH - Please verify my answers**

so capitalize it if it was italic like SCRAWNY
*November 26, 2015*

**ENGLISH - Please verify my answers**

scrawny has a negative connotation :)
*November 26, 2015*

**Maths**

Well, when is that slope equal to 1 ? 3 x^2 + 2 x - 1 = 0 (3x-1)(x+1) = 0 x = 1/3 or x = -1
*November 26, 2015*

**math**

[ (9.55/4) + 5 ] 1.25
*November 26, 2015*

**Pre Calculas**

no log x^2 = 2 log x I have no idea what in56 means could you mean 5 in or ln 56 or what? if you mean ln 56 / ln 7 that is not ln 8 ln 8 = ln (56/7) = ln 56 - ln 7
*November 26, 2015*

**physics**

h = distance up = 50 sin 10 m g h = 800 * 9.81 * 50 sin 10 Joules
*November 26, 2015*

**physics**

If something wants to move at a certain frequency, like a kid on a swing, then if you push it at that frequency it moves faster and faster and further and further.
*November 25, 2015*

**Algebra**

7 * 7 = 49 4 * 7 = 28
*November 25, 2015*

**science help PLS**

THINK ! as you squeeze it the particles get closer together and therefore the density increases.
*November 25, 2015*

**Physics**

Vboulder = a t x boulder = (1/2) a t^2 25 = (1/2) .85 t^2 so t = 7.67 seconds to do the first 25 m so at that t Vboulder = .85 * 7.67 = 6.52 m/s That is part (a) now it has to go 75 meters starting with v = 6.52 v = 6.52 + .85 t where t is time to do those 75 m to entrance 75...
*November 25, 2015*

**calculas**

dy/dx = slope = -1/x^2 at (1,2) y = 2 and slope = -1 where does that hit the x axis at x = 2 it is at y = 2-1 = 1 at x = 3 it is at y = 1-1 = 0 so it hits anything at (3,0)
*November 25, 2015*

**physics**

weight force down slope = m g sin 25 normal force = m g cos 25 so friction force down slope = .6 m g cos 25 therefore we need F = m g ( sin 25 + .6 cos 25)
*November 24, 2015*

**Algebra 2**

You are welcome.
*November 24, 2015*

**Algebra 2**

A, Not really. That first parabola has its vertex right on the x axis at x = -1 so it only hits the axis there B, = (x+3)(x+3), same deal, vertex on x axis at x = -3 so barely touches once C. b^2-4ac = 49-40 so yes, hits twice D. b^2-4ac = 36-32 yes again hits twice (x+4)(x+2...
*November 24, 2015*

**Algebra 2**

x^2 x^-1 = x^1 or x^2/x^1 = x^1 also y^5/y^3 = y^2
*November 24, 2015*

**Algebra 2**

I do not see a division 6 x^1 y^2
*November 24, 2015*

**physics**

You are welcome.
*November 24, 2015*

**physics**

I get 19.4 degrees to three significant figures
*November 24, 2015*

**physics**

all that matters is mu static normal force = m g cos T so Friction force = .353 m g cos T force down slope = m g sin T m g sin T = .353 m g cos T tan T = .353
*November 24, 2015*

**math**

(19+4)(13+4) = 23 * 17
*November 24, 2015*

**Chemistry**

mol of CO2 is 12+32 = 44 grams so we have 3.5/44 = .08 mol of CO2 at stp 22.4 liters/mol .08*22.4 = 1.78 liters
*November 24, 2015*

**math**

14 times 45
*November 24, 2015*

**Algebra 2**

2*3 = 6 2-1 = 1 -3+5 = 2 so 6 x y^2
*November 24, 2015*

**Algebra 2**

halfway between 3 and 11 (3+11)/2 = 7 so that is the x location of the vertex y = (7-3)(7-11) 4*-4 = -16 so I get (7, -16)
*November 24, 2015*

**Math**

4000 = 1600 + 300 ln a ln a = 8 a = e^8 = 2980 or 3000
*November 24, 2015*

**Math**

3.43502 * 100,000 - 3.43502 * 10^5
*November 24, 2015*

**math**

2 x - 5 = 15 add 5 to both sides 2 x = 20 multiply both sides by 1/2 x = 10 ============== check 2 (10) - 5 20 - 5 15 sure enough
*November 24, 2015*

**math**

You are welcome.
*November 24, 2015*

**math**

not unless he is a baby That is around 18 pounds in American units, too young to estimate his own mass.
*November 24, 2015*

**math**

close enough for mixing lemonade :)
*November 24, 2015*

**math**

well, I used units that are familiar to me. perhaps you know a quart is about a liter? a quart is 32 oz so 12 ox = 12/32 = 3/8 of a quart or liter = .325 quart which is not greatly different from .355 liter
*November 24, 2015*

**math**

well, a pint is a pound the world around :) In the Netherlands, 500 mL is called a pint so 355 mL is about .71 pint here 16 oz is called a pint 12/16 = .75 pint not bad :)
*November 24, 2015*

**Calculus III**

well, forget the 18 for a while 18 ∭ (x+y)dz dy dx integrate over z from y to x 18 integral (x+y)(x-y) dy dx 18 integral (x^2-y^2) dy from y = 0 to x dx 18 integral (x^3 -x^3/3) dx from x=0 to 1 18 [ (2/3) x ^3 dx ] from 0 to 1 12 (1^4/4) 3 check my arithmetic, did that ...
*November 24, 2015*

**Phyical Science**

Who not to ask: power companies of any sort, coal, natural gas, oil, hydro, solar, nuclear energy professionals. They all just want to sell the mayor on their technologies and the truth is not in them. Possible sources of information: Universities, engineering firms ...
*November 24, 2015*

**Calculus**

You are welcome.
*November 24, 2015*

**Calculus**

f(x) grows by 5 when x grows by 1 f(5 = 14 5 * 14 = 70 = f(6) f(x) = c 5^x f(5) = 14 = c 5^5 = 3125 c c = 14/3125 f(x) = (14/3125) 5^x if x = 6 f(6) = (14/3125)5^6 = (14 /3125) 15625 = 70
*November 24, 2015*

**MUBANGA CHIPOYA DAY SCO SCHOOL,SCIENCE**

the weight is a FORCE, you might measure with a scale the mass is a fundamental unit (Force / acceleration)
*November 24, 2015*

**difference between mass and weight**

m, the mass. is the same on the moon m g, the weight, is about (1/6) weight on earth
*November 24, 2015*

**MUBANGA CHIPOYA DAY SCO SCHOOL,SCIENCE**

grams and kilograms are mass (m) Newtons and pounds are weight (m g)
*November 24, 2015*

**math**

3x+5 - x = 7x+4 -(3x+5) 2x+5 = 4 x -1 2 x = 6 x = 3 so 3 , 14 , 25 constant difference = 11 a1 + d(n-1) 3 + 11 * 8 = 91
*November 24, 2015*

**maths**

sin angle = 22/27
*November 24, 2015*

**math**

4. proportional means y = constant times x I think a) is really y = (1/2)x which works 5. y = x/2 is the one we chose so 0 = 0/2 works 1 = 2/2 works 2 = 1/2 no way 1 = (1/2)/2 no way
*November 24, 2015*

**no way, please check**

from the top of the tower you do not look UP to the house. Do you have the sign wrong or the word wrong or what?
*November 24, 2015*

**do not believe**

top of a tower the angle of elevation is 24° You mean angle of depression maybe , negative, house surely lower
*November 24, 2015*

**Analytic Geometry**

(x, y) 6-2 = 4 which is present x difference 4*4 = 16 2 - 16 = -14 new x then y 7 - 3 = 4 lol , same difference 4*4 = 16 3 - 16 = - 13 so (-14,-13)
*November 24, 2015*

**hard to tell**

This seems to be missing the problem statement.
*November 24, 2015*

**Math algebra**

presently is .6 * 3.6 = 2.16 af .4 * 3.6 = 1.44 h2o should be .5 * 3.6 = 1.8 af 1.8 h2o add x liters water take out .6 x af and .4 x water new af = 1.8 = 2.16 - .6 x so .6 x = .36 x = .6 ============== check new water = 1.44 - .4(.6) + .6 = 1.8 whew
*November 24, 2015*

**Math**

been there, done that
*November 24, 2015*

**Math**

r and (r + 4) ---> total of 2r+4 (2r+4)8 = 896
*November 24, 2015*

**Algebra 1- Please help whenever you get the chance**

You are welcome.
*November 24, 2015*

**Algebra 1- Please help whenever you get the chance**

Just do it. .16 ( 872 ) + 24.54 = 139.52 + 24.54 = 164.06
*November 24, 2015*

**Parentheses !!!**

what is the numerator and what is the denominator?
*November 23, 2015*

**Geometry**

G = 180 - 52 - 60 = 68 so H is smallest angle so the side opposite H is shortest
*November 23, 2015*

**physics**

Ac = m v^2/R so side force from friction = m v^2/R = .5 m g v^2/R = .5 g R = 2 v^2/g
*November 23, 2015*

**physics**

v = omega r so omega = v/r I =(1/2) m r^2 (1/2) m v^2 + (1/2) I omega^2 =(1/2) m v^2 + (1/2)m r^2 (v^2/r^2) = m v^2 half the energy is linear and half is rotational ;)
*November 23, 2015*

**Physics**

Well, I would have used energy loss of potential energy = gain in kinetic energy + work done by wind loss of potential energy = m g h = 79.5 (9.81) (62.8) Joules = 48,977 Joules work done by wind component of horizontal wind opposite direction of motion = 98 cos 28 Newton ...
*November 23, 2015*

**physics**

1 revolution = 2 pi r = 6 pi cm 20 revolutions in 5 seconds so 20 * 6 * pi centimeters
*November 23, 2015*

**in case you do not know about max range**

http://www.wired.com/2010/09/maximum-range-in-projectile-motion/
*November 23, 2015*

**physics**

do you know max range is 45 degrees above horizontal ? If so speed S u = horizontal speed = s cos 45 Vi = initial vertical speed = S sin 45 time in air = 25/u half time in air = time rising = 12.5/u = t v = Vi - 10 t v = 0 at top of rise phase so Vi = 10 t Vi = 10 (12.5/u) S ...
*November 23, 2015*

**physics**

integrate from x = 0 to x = 10 dm/dx = 6 kg/m F = x * 6 * 9.81 d work = F(x) dx d work = x (6)(9.81) dx = (x^2/2) * 6 * 9.81 from 0 to 10 =(100/2)*6*9.81
*November 23, 2015*

**Math**

Kilo means "thousand".
*November 23, 2015*

**Math**

yes !
*November 23, 2015*

**Math**

Chart? you have got to be kidding. You multiply kliograms by 1000 to get grams. That means three zeros to the right.
*November 23, 2015*

**Math**

Huh ? a kilogram is 1000 grams 2500 grams
*November 23, 2015*

**Calculus**

d^ [(-1/r) t] dt -re^[(-1/r) t] + c
*November 23, 2015*

**Physics**

rate = initial rate e^-kt 1/2 = e^-k(5600) ln .5 = -5600 k -.693147 = - 5600 k so k = 1.2378 *10^-4 now 1 = 16 e^-1.2378 *10^-4 t ln 1/16 = -1.2378 *10^-4 t t = 22,400 or do it in your head 1/16 = (1/2)^4 so 4 * 5600 = 22400 :) LOL
*November 23, 2015*

**huh?**

what does mA mean?
*November 23, 2015*

**gibberish**

Please type the question more carefully
*November 23, 2015*

**math**

Least Common Denominator = 20 4/5 = 16/20 1/2 = 10/20 1/4 = 5/20 now arrange them
*November 23, 2015*

**Dr vsec**

say we have a cubic piece of ice one centimeter on a side floating on water: Ice volume = 1.000 cm^3 Ice mass = .917 g so mass of water displaced = .917 g volume of water displaced = .917 g/1.03 g/cm^3 = .890 cm^3 which is the volume of ice below water surface volume of ice ...
*November 23, 2015*

**science**

s^3 = .4 m^3 so s = .737 meter mass = density * volume = 12 * .4 = 4.8 kg
*November 23, 2015*

**Stats**

32,000 mi ( 1 gal/12 mi) = 2667 gal for SUV 32,000 mi (1 gal/50 mi) = 640 gal for hybrid so use 2667-640 = 2027 gal less so 2027 * $2.50 = $5067.50 savings
*November 23, 2015*

**Math**

x = xi * 2^n 3 = 2^n log 3 = n log 2 n = 1.585 24 * 1.585 = 38 hours
*November 23, 2015*

**Physics**

Just use imagination From car: center (the axle) does not move bottom moves back at 80 with the road so top has to move forward at 80 from roadside: center moves forward at 80 top forward at 160 bottom still where it touches stationary ground the axle is not accelerating the ...
*November 23, 2015*

**Physics**

Vertical problem: How fast does it fall? (1/2) m v^2 = m g h so v = sqrt (2 g h) Horizontal problem: u = constant = 13.9 so tan 40 = sqrt(2 g h) /13.9
*November 23, 2015*

**math**

The third one looks most tightly clustered around 3
*November 22, 2015*

**scenice**

The point is that the two births are statistically independent.
*November 22, 2015*

**math**

What does your book say about parabolas and circles I wonder/
*November 22, 2015*

**math**

Well, I think you should mention real world examples. a parabolic path is followed by a thrown object if you can neglect air friction for example. A stick bent in several places by transverse forces forms cubics - I am not sure you are supposed to know that though. I bet you ...
*November 22, 2015*

**math**

also maybe circle (x-h)^2 + (y-k)^2 = r^2 center at (h,k) radius r
*November 22, 2015*

**math**

I see you working with Ms Sue below: Think about a parabola and a cubic y = a x^2 + b x + c and y = a x^3 + b x^2 + c x + d parabola changes direction once, either sheds water or holds it, two roots cubic changes direction twice, three roots - s shaped
*November 22, 2015*

**College Physics- buoyancy problem**

You are welcome :)
*November 22, 2015*

**College Physics- buoyancy problem**

But you left out the weight of the Helium At stp a mole of Helium is 22.4 liters and a mole of He is 4 grams / mol
*November 22, 2015*