Monday

March 2, 2015

March 2, 2015

Total # Posts: 20,651

**Calculus**

You have to say what is the lower limit and what is the upper limit of your integral to do a definite integral I guess your function is f(x) = x for x < 1 and f(x) = 1/x for x >/= 1 (-2)^3 = -8 so when x<1 integral = -8 [x^2/2 upper-x^2/2 lower] and for x >/= 1 ...
*December 1, 2014*

**Physics**

capacitance = charge/unit voltage C = coulombs / volts
*December 1, 2014*

**physics**

Force = change in momentum/change in time 100 = change in momentum / 5 change in momentum = 500 Newton meters or Joules
*December 1, 2014*

**Math**

55 would be called 60 54.9999999999 would be 50 but 55.00000000001 would be 60 so if it starts with 55 it is 60 It does not make a whole lot of sense, but one must decide consistently :) 5 is 10 but 4.99999999 is 0
*December 1, 2014*

**MATH**

-9 - 3m -3m - m^2 = - m^2 - 6 m - 9
*December 1, 2014*

**MATH**

8 m - 8 n + 64 distributive property
*December 1, 2014*

**Trig**

Vs + Vc = 19.3 cos 33.7 i + 19.3 sin 33.7 j Vs = 17.5 cos 26.3 i + 17.5 sin 26.3 j so Vc x = 19.3 cos 33.7 - 17.5 cos 26.3 and Vc y = 19.3 sin 33.7 - 17.5 sin 26.3 |Vc|^2 = (Vc x)^2 + (Vc y)^2 tan angle N of E = Vc y/ Vc x of course in the real world navigators measure angles ...
*December 1, 2014*

**Physics- formula help**

if it is falling m g down positive F air resistance up a down positive Weight - Fair resistance = m a m a = m g - Fair resistance if the F air resistance were equal to the weight, mg , then the acceleration would be zero m (g-a)
*December 1, 2014*

**CALC 1**

you already have h', the first just take one more x e^x + e^x = e^x (x+1) e^x always + so where x + 1 is + x> -1
*November 30, 2014*

**Calculus**

My arithmetic was wrong, go with Steve !
*November 30, 2014*

**Calculus**

y = (3 -x^3)-(1/3) dy/dx = -(1/3) (3-x^3)^-2/3 (-3x^2) = + x^2 /(3-x^3)^(2/3) E
*November 30, 2014*

**AP Calculus**

since it is a cubic, there will presumably be two f' = 0 = 3 x^2 + 6 x = 3x ( x+2) x = 0 and x = -2 you find f(x) there
*November 30, 2014*

**Calculus**

top = (x+9)^.5 - 3 d top/dx = .5 (x-9)^-.5 ---> oo bottom = x d bottom/dx = 1 --->1 so ----> oo/1
*November 30, 2014*

**Calculus,Reaction rates**

at 1 second d = sqrt(10^2 + 10^2 + 5^2) = sqrt 225 d^2 = 100 + 25 t^2 + 100 t^2 d^2 = 100 + 250 t^2 2 d dd/dt = 500 t v = dd/dt = 250 t/d at t = 1 v = 250/15 = 16.7 ft/s
*November 30, 2014*

**Calculus**

x^2 f' + 2 x f = x [ x f' + 2 f ]
*November 30, 2014*

**Calculus**

dy/dx = slope = m for this ellipse 2 x dx/dx + 6 y dy/dx = 0 at(1,1) 2(1)+6(1)dy/dx = 0 dy/dx = m = -1/3 so y = -(1/3) x + b at (1,1) 1 = -1/3) + b b = 4/3 so y = -(1/3) x + 4/3 or 3 y - -x + 4
*November 30, 2014*

**physics**

V = Vi + a t 40 = 20 + 2 t t = 10 x = 20 t + (1/2) a t^2 x = 200 + 100 x = 200
*November 30, 2014*

**physics**

F = kX 25 (20/10)
*November 30, 2014*

**Science**

a = change in v/change in time a = 60/8.2 = 7.32 horizontal so horizontal force = 94*7.32 = 688 N vertical force up = weight = m g = 94*9.8 = 921 N net force = sqrt(921^2 + 688^2)
*November 29, 2014*

**two step equation-fraction**

if it is 4 + (m/3) = 5/6 then the answer is -19/2 which is -9 1/2 as Steve told you if it is (4 + m)/3 = 5/6 then the answer is -9/6 = -1 1/3 there is no perturbation I can make on what you typed to make it come out -3/2
*November 29, 2014*

**two step equation-fraction**

So maybe you typed the original question wrong maybe you meant: """"""""""""""""""" please help me step by step thanks (4+m)/3=5/6 """"""""&...
*November 29, 2014*

**two step equation-fraction**

6 m/3 = 2 m
*November 29, 2014*

**chemistry**

method is correct and I agree with the aritmetic
*November 29, 2014*

**phyics**

if board mass = m down force = m g so friction force must be m g mu F = m g F = m g/mu
*November 29, 2014*

**Math**

3 x dy/dx + 3 y -4 x +10 y dy/dx = 0 dy/dx (3 x+10y) = (4x-3y) dy/dx = (4x-3y)/(3x+10y)
*November 29, 2014*

**chemistry**

You just ignore the excess compounds. all that is important here is for every 2 mols of H2SO4 you get one mol of CaH4P2O8
*November 29, 2014*

**chemistry**

KOH = 39+16+1 = 56 grams/mol 14.3/56 = .255 mols .255/V = .55/1 V = .464 Liter
*November 29, 2014*

**m**

4(9) + 7(9) + 2 36 + 63 + 2
*November 29, 2014*

**ph**

work is force in direction of motion * distance moved so we need that angle between the motion and the force For the force: Tan theta = 5.8/3 theta = 62.65 degrees from x axis now the force is 100 deg from x axis so angle between force and motion = 100 - 62.65 = 37.35 so ...
*November 29, 2014*

**Physics**

I of bar around base of bar = (1/3) m L^2 = (1/3)(1.5)(.75)^2 = .281 kg m^2 initial angular momentum of bird around base of bar = m (2L/3)^2 [V/(2L/3)] = m (2L/3)V = .5 (.5)(2.25) = .5625 If the bird just stopped, then that is the angular momentum of the bar .5625 = I omega...
*November 29, 2014*

**physics**

time to fall: h = .5 g t^2 so t = sqrt (2 g h) time for sound to rise = h/c 5.3 = h/c + sqrt (2 g h) sqrt (2 g h) = 5.3 - h/c 2 g h = 5.3^3 - 10.6 (h/c) + h^2/c^2 look up c at 20 deg C and then solve the quadratic
*November 29, 2014*

**Calculus I**

for example see http://www.jiskha.com/display.cgi?id=1289778468
*November 28, 2014*

**Calculus I**

c = 10 x^2 + 4 x h but h = (100 - x^2)/4x c = 10 x^2 + 4x (100-x^2)/4x c = 10 x^2 + 100 - x^2 c = 9 x^2 + 100 cost is minimum as x goes to zero of course since the bottom material is so expensive. I have a hunch that the constraint should be on the volume, not the area.
*November 28, 2014*

**pre-algebra**

I could graph minutes on the x axis and pages read on the y axis so B is ok I could graph sandwiches on x and peanut butter on y I could graph toys on x and batteries on y HOWEVER oranges from a trip to the store is just a point.
*November 28, 2014*

**Chemistry**

p = 1.67*10^4 kilo Pascals V = 43.8 L T = 273 + 24 = 297 K R - 8.314 Liters kilopascals/deg K PV = n R T n = (1.67*10^4)(43.8)/ [ 8.314*297 ] n = 296 mols 296 * 40 grams/mol = 11840 grams or 11.84 kg
*November 28, 2014*

**Physics**

No, did you read what I wrote? You have to have an integral number of HALF wavelengths 2 m has one antinode in the middle 1 m has 2 antinodes at .25 and .75 .666666 m has 3 antinodes at 1/4, 1/2, and 3/4 (1.5 whole waves in there) .5 m has 2 whole waves in there, 4 antinodes ....
*November 28, 2014*

**Physics**

Try to draw a wavelength of .75 meters in your 1 meter string without a crest, not a node, at one end. D is allowed for sure, the lowest resonance. Draw it
*November 28, 2014*

**Calculus**

You are welcome.
*November 28, 2014*

**Calculus**

dy/dx = slope = 3 x^2 - 6 x + 5 where is that max or min ? where its derivative is 0 d^2y/dx^2 = 0 = 6 x - 6 so x = 1 is that a max or a min? take the ext derivative, if + it will be headed up and a min. d^3y/dx^3 = 6 that is positive so the min slope is at x = 1 that slope is...
*November 28, 2014*

**Math typo**

.... she walks 1 1/4 of an hour. Huh?
*November 28, 2014*

**Physics**

It only weighs about 270 N if 27 kg He is pulling with 454 N That is not right unless it is hooked to an anchor. It should probably be 270 kg for about 2700 N weight
*November 28, 2014*

**Physics**

Normal force on floor = m g - 454 sin 37 friction force = mu * normal force but friction force = 363 N you said so 363 = mu (27*9.8 - 454 sin 37)
*November 28, 2014*

**Physics**

ah, as happy as he ever got that is.
*November 28, 2014*

**Physics**

By the way I went to some pain to elaborate on this because a scientist named Edward Teller (Google him) asked me that very question in a slightly different manner when I was interviewing for a fellowship many years ago. I gave him the answer I just gave you and he was happy :)
*November 28, 2014*

**Physics**

It is very hard for a wave to change frequency. You have to store some of the waves somewhere if you do that because in the end the same number must enter one end of the box as come out the other. Think ocean waves coming into a beach, They slow down in the shallow water so ...
*November 28, 2014*

**physics**

Cut line, 2/3 and 1/3 Secure end of shorter line to tree. Reeve through block at car and secure to the hook on your second block which will be a traveling block Now secure the end of your longer line to the tree Run that line through the sheeve on the traveling block now look ...
*November 28, 2014*

**Physics**

(specific gravity of this oil*7 + 8)62.4 in pounds/ft^2 divide by 144 to get psi, pounds per square inch I do not know the ratio of this oil density to that of water
*November 28, 2014*

**Calculus**

How do we know h = 15 ? If we do not know h, then the solution is something that looks like a space needle :) L * w * h = 2160 if h = 15 L * w = 144 L = 144/w cost = c = 5(L*w) + 2 L*h + 2 w*h c = 5 L w + 2 w h + 2 L h if we know h = 15, then c = 5 L w + 30 w + 30 L c = 5*144...
*November 28, 2014*

**Math**

sin 63 = h/25
*November 28, 2014*

**Alg !**

http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html
*November 28, 2014*

**whoops**

1 = 1/24 r^3 r^3 = 24 r = 2 sqrt 3 again can not be both
*November 28, 2014*

**math**

a r^2 = 9 a so r = 3 ar = (1/24) a r^4 r = (1/24) r^3 24 = r^2 but r = 3, can not be 3 and sqrt 24 a r^3 is fourth term 27 a = ? 48 ? a = 48/27 ? I think you have this messed up.
*November 28, 2014*

**math**

a ar^1 ar^2 ar^3 ----- ar^(n-1) ar^2 = 9a so a = 3 a r = (1/24) a r^4 r = (1/24) r^4 r^3 = 24 = 8*3 remember this so r = 2 *3^(1/3) fourth = a r^3 = 3 *24 = 72
*November 28, 2014*

**calculus**

a = -g = -9.8 m/s^2 The statement gives you the answer. v = integral a dt = -9.8 t + c at t = 0 v = Vi = 5 m/s so c = 5 v = -9.8 t + 5 h = integral v dt = 5 t -(9.8)/2 t^2 + cc when t = 0 h = Hi = 442 so cc = 442 h = 442 + 5 t - 4.9 t^2 (check your physics book :) at top, v = ...
*November 28, 2014*

**physics, how to find the height**

At max height all velocity is horizontal u = 26 but u = 65 cos Theta so Theta, the angle shot above horizontal = 66.4 deg so Vi = initial up speed = 65 sin Theta = 59.6 at top vertical speed = 0 so 0 = 59.6 - 9.8 t where t is rise time t = 6.08 seconds going up H = 0 + 59.6 t...
*November 27, 2014*

**physics**

Vi = 2.7 m/s h = 11 + 2.7 t = 4.9 t^2 0 = 11 + 2.7 t - 4.9 t^2 at ground 4.9 t^2 - 2.7 t - 11 = 0 t = [ 2.7 +/- sqt (2.7^2 +44*4.9) ]/9.8
*November 27, 2014*

**Math**

been there, done that http://www.jiskha.com/display.cgi?id=1417133335
*November 27, 2014*

**physics**

24 = (1/2)g t^2 48 = 9.8 t^2 t 2.21 seconds
*November 27, 2014*

**algebra**

.3 a + .8 b = .4 * 10 a + b = 10 .3 a + .8 b = 4 .8 a + .8 b = 8 ---------------- subtract -.5 a = - 4 a = 8 so b = 2
*November 27, 2014*

**Pre-Calc.**

LOL, but if two angles are 60 then so is the third and it is an equilateral triangle :) base = 24 12^2 + h^2 = 24^2 h^2 = -(3*4)^2 + (6 *4)^2 h^2 = 4^2 ( -9+36) = 4^2 (27) = 4^2*3^3 h = 4*3 * sqrt 3 h = 12 sqrt 3
*November 27, 2014*

**physics**

The mechanical energy of the system is the sum of kinetic and potential energy. In this ideal world it does not change with time. Since you found the maximum speed use (1/2) m v^2
*November 27, 2014*

**math**

a b c c = 2 a a + b + c = 14 a b 2a 3 a + b = 14 ones digit is even 1 b 2 ---> 3+b=14, b = 11 no 2 b 4 ----> 6 + b =14, b = 8 ok so 2 8 4
*November 27, 2014*

**math**

1 2 4 8 16 1 2^1 2^2 2^3 2^(n-1) a a2^1 a 2^2 .... geometric sequence with a = 1 r = 2 n = number of days 2^59 = area 2^x = 2^59/2 x = n-1 = 58 so 59 days which we could have said right off because if you cover the whole lake in 60 days then the day before you must have half ...
*November 27, 2014*

**algebra 2**

16 x^2 - 56 x = 0 x (16 x^2 - 56 ) = 0 x = 0 or x = 56/16
*November 27, 2014*

**math**

a ar^1 ar^2 ar^3 .... ar^(n-1) so a r^2 = 9 a a r^1 = (1/24)ar^4 ----------------------- ----------------------- so r = 3 a(3) = (1/24)a (3)^4 This is not possible. You have a typo.
*November 27, 2014*

**Math**

You are welcome.
*November 27, 2014*

**Math**

3/2 = L/b = 1.5/b 3 b = 3 b = 1
*November 27, 2014*

**Physics**

F = m a weight = m a a = -mg/m = - g in other words acceleration is down at -10 m/s^2 dv/dt = a = -10 so v = -10 t + c but at t = 0, v = +10 so c = 10 and v = -10 t + 10 now at the top, v = 0 0 = -10 t + 10 so at the top when t = 1 if v = -10 t + 10 then h = Hi + 10 t - 5 t^2 ...
*November 27, 2014*

**math**

I do not have a politically correct answer to your preamble question.
*November 27, 2014*

**math**

2 x + 3 y = 92 4 x - 7 y = 2 4 x + 6 y = 184 4 x - 7 y = 2 --------------------- 13 y = 182 y = 14 etc
*November 27, 2014*

**physics**

a quantity that has both magnitude and direction. for example you can measure the speed or magnitude of velocity of a car with a speedometer. However to specify the velocity vector you also need a compass. 20 km/hour is a scalar magnitude, speed 20 km/hour EAST is a vector.
*November 27, 2014*

**physics, how to find the height**

a = -g with g unknown at h = 0, Pe = 0 and Ke = (1/2)m Vi^2 = total energy at h = Htop , v = o and Pe = m g Htop = (1/2) m Vi^2 so Htop = Vi^2/2g at h = Htop/4 Pe = m g (Htop/4) = m Vi^2/8 total energy still = m Vi^2/2 so Ke = (3/4) (1/2)m Vi^2 so it still has (3/4) of initial...
*November 26, 2014*

**U.S. History Help!!!!!!!**

1 c I think (there were a lot of tories) 2 a 3 d
*November 26, 2014*

**Math**

.70 p = 72.09 p = 72.09/.7 = 102.99
*November 26, 2014*

**Language Arts**

I would pick B.
*November 26, 2014*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html
*November 26, 2014*

**six sigma**

http://davidmlane.com/hyperstat/z_table.html
*November 26, 2014*

**physics**

vertical problem Vi = 2390 sin 49.6 v = Vi - 9.8 t at top v = 0 so t = Vi/9.8 at top that is half the trip hits ground at tg = Vi/4.9 Now the horizontal problem u = 2390 sin 49.6 range = u tg range = 2390 sin 49.6 * Vi/4.9 so range = 2390^2 sin 49.6 cos49.6 /4.9 = 575369 ...
*November 26, 2014*

**math**

9/30 = 3/10
*November 26, 2014*

**Bus. Math**

s - .55 s = 5.12 .45 s = 5.12 s = 11.38 check 5.12 + .55(11.38) = 11.38
*November 26, 2014*

**math**

18+3 = 20 + 1 = 21 27 + 4 = 30 + 1 = 31 practice by drawing the problem on a number line.
*November 26, 2014*

**gen chem**

1/L = 10^7 (1/49 - 1/81) 1/L = 10^7( .00806 ) = .806* 10^4 L = 1.24 * 10^-4 meters
*November 26, 2014*

**MATHEMATICS**

Go back and read: 5 .55 That is a but you asked for term 6 which is a r^5 5.55 * 1.44^5 about 34.4
*November 26, 2014*

**Math**

.25 x = 3 x = 300/25 = 12
*November 26, 2014*

**Math**

.2 x = 80 x = 80/.2 = 800/2 = 400
*November 26, 2014*

**Chem**

Temp = 37 + 273 = 310 K P V = n R T V = .1 R (310)/92,000 but R = 8.315 Pascals m^3/mol K V = .1 * 8.315 * 310 /92,000 meters^3
*November 26, 2014*

**math**

(1)hypotenuse = straight home sqrt(36+64) = 10 straight is 10 miles same way is 6+8 = 14 miles (2) hypotenuse of 3,4 5 right triangle is 5 5*6 = 30 plus enough for the knots :) (3)diagonal (hypotenuse) length is the longest sqrt (42^2 + 84^2) = 93.9, so no
*November 26, 2014*

**Chem please help**

You do not need the s on https http://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/
*November 26, 2014*

**Chem please help**

or better: https://www.boundless.com/biology/textbooks/boundless-biology-textbook/metabolism-6/potential-kinetic-free-and-activation-energy-69/free-energy-345-11482/
*November 26, 2014*

**Chem please help**

http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/helmholtz.html
*November 26, 2014*

**Math--1 question**

30 31 32 -- 33 -- 34 35 54 median clearly is 33 mean = sum /7 mode - no value occurs more than any other ranges from 30 to 54
*November 26, 2014*

**Coordinate Geometry (Algebra 1)**

First RS slope = (4 - -5) / (-8 - 4) = 9/-12 = -3/4 so it is y = -(3/4) x + b no need to find b, all we need is the slope -3/4 so slope of perpendicular = -1/m = +4/3 so 4/3 = (y-6) /( -3 - 0) 4/3 = (y-6)/-3 -4 = y-6 y = 2
*November 26, 2014*

**MATHEMATICS**

Been there, done that check below
*November 26, 2014*

**MATHAMATICS**

That is a but you asked for term 6 which is a r^5 5.55 * 1.44^5 about 34.4
*November 26, 2014*

**MATHAMATICS**

a ar ar^2 ar^3 etc a r^n-1 a r^4 = 24 a r^7 = 72 r^7/r^4 = 72/24 r^3 = 3 r = 3^(1/3) a 3^(4/3) = 24 a = 24 * 3^-(4/3) a = 5.55 r = 1.44 check a r^4 = 24.01 a r^7 = 72.04 ok
*November 26, 2014*

**physics**

initial momentum = 0 so final momentum = 0 0 = 80*1.5 + 120 * V V = - 120/120 = -1 meter/second
*November 26, 2014*

**math**

the first place on the right is either 0 or 1 times 2^0 which is one just as in base 10 the first place on the right is 0 1,2...9 or one of those numerals times 10^0 which is one the second place on the right is either 0 or 1 times 2^1 which is 2 just as in base 10 the second ...
*November 26, 2014*

**math**

1 * 2^0 = 1 0 * 2^1 = 0 1 * 2^2 = 4 1 * 2^3 = 8 so 13
*November 26, 2014*

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