Thursday

July 2, 2015

July 2, 2015

Total # Posts: 21,387

**calc**

x^2 + z^2 = r^2 is a circle with radius r read what mathmate wrote for you.
*December 2, 2014*

**MATH**

how many ways to combine five things three at a time? n!/[r!(n-r)!] 5!/[3!(2!)] 5*4/2 10 ========================== 4 along each long side with no ends 5 along each short side including end posts 9*2 = 18
*December 1, 2014*

**Please help Damon**

You are welcome.
*December 1, 2014*

**Please help Damon**

looks right to me
*December 1, 2014*

**physics**

Just follow my way using the diameter and multiply by 4 at the end. A = pi d^2/4
*December 1, 2014*

**physics**

r = .019/2 = .0095 you have a decimal point off in the diameter too
*December 1, 2014*

**physics**

.5/306 = .00163, not .0163
*December 1, 2014*

**physics**

whoops I used diameter use 4*1.45 = 5.8 m/s
*December 1, 2014*

**physics**

I get 1.45 m/s
*December 1, 2014*

**physics**

area of pipe * speed of water = Q = flow volume/second area = pi (.019)^2 volume = 0.5 m^3 time = 5.1*60 = 306 so pi (.019)^2 V = .5 m^3/306 s solve for V in m/s
*December 1, 2014*

**History Help?**

He is called the father of Texas because he brought the 300 anglo colonist families in to a land grant he obtained from the Spanish before Mexico split from Spain.
*December 1, 2014*

**Calculus**

2/12pi = 1/(6pi) agree
*December 1, 2014*

**Calculus**

dV/dt = 2 cm^3/s dV/dh = surface area = pi r^2 dV/dt = dV/dh * dh/dt so dh/dt = dV/dt / pi r^2 so you need r, the radius of the surface 2 cm up from the bottom of the 4 cm radius sphere I do not remember the length of a circle sector halfway from the center to the edge, look ...
*December 1, 2014*

**Physics**

the hint is the answer v = sqrt (2*9.8*.5) from m g h = (1/2)mv^2 is 2 g h = v^2 the potential energy of a chunk of water at the surface is its kinetic energy exiting at the bottom you can do it with Bernouli if you want to get sophisticated :) p + rho g h + (1/2) rho v^2 = ...
*December 1, 2014*

**AP Calc**

well on my calculator 84 -14*4) = 28
*December 1, 2014*

**AP Calc**

4x +y = 84 so y = (84-4x) Volume = x^2 y = x^2(84-4x) V = 84 x^2 - 4 x^3 dV/dx = 0 for max or min 0 = 168 x - 12 x^2 0 = x (168-12 x) x = 0 not very useful so x = 168/12 = 14 y = length = 28 interesting, length twice the side dimension
*December 1, 2014*

**Algebra 1**

Graph those points. There is no instance where you have more than one value of y for a value of x. Therefore it is a function.
*December 1, 2014*

**math error**

99*50 = 4950
*December 1, 2014*

**math**

try 1 to 5 1 + 2 + 3 + 4 + 5 = 15 that is five numbers the middle one is 3 which is (1+5)/2 so try 1 to 99 that is 99 numbers the middle one is (1+99)/2 = 50 so try 99*50 =100*50 - 99 = 4901 ================================ try 1+3+5 = 9 which is 3 (1+5)/2 = 3*3 try 1+3+5+7 = ...
*December 1, 2014*

**MATH**

app makes x journeyman makes 3 x master makes 4.5 x 8.5 x = 5950 x = 700 etc
*December 1, 2014*

**physics**

no L the same, g different
*December 1, 2014*

**physics**

L/g important, not m
*December 1, 2014*

**physics**

k and m the same
*December 1, 2014*

**Algebra 2**

we have a circle with radius 2 sqrt5 and center at the origin and a parabola that looks like: 6 y = x^2-28 y = (x^2-28)/6 opens up (holds water) zeros at x = +/- sqrt 28 so vertex at x = 0 then y of vertex at -28/6 NOW SKETCH A GRAPH now do algebra x^2 + y^2 = 20 x^2 - 6 y = ...
*December 1, 2014*

**Algebra 2**

Very similar to the one I just did for you, another parabola intersecting a circle
*December 1, 2014*

**sci**

nm it is b :) despite its name, the radiator works by warming the air around it which rises and circulates around the room (convection)
*December 1, 2014*

**algebra 2**

13+x = +/- 5 sqrt(10) x = -13 +/- 5 sqrt(10)
*December 1, 2014*

**sci**

Heat goes from hot to cold by itself to move it from cold to hot requires work, like an air conditioner I would have chosen D
*December 1, 2014*

**Math**

m mN mN^2 mN^3 .......mN^(n-1) number on day n = m N^(n-1)
*December 1, 2014*

**physics**

force = change in momentum/change in time or m A if m is constant change in momentum/3 = 200 change in momentum = 3*200 kg m/s
*December 1, 2014*

**math**

12 x = 96 so x = 96/12 then 2 x + 2 (12) = perimeter
*December 1, 2014*

**sci**

yes microwaves are electromagnetic radiation
*December 1, 2014*

**Science**

14.) Answer = Habitat Destruction Yes 15.) Answer = Carbon Dioxide - I Think yes, Methane is worse but fossil fuels produce CO2 16.) Answer = ___________ reverse 17.) Answer = Ozone Layer yes 18.) Answer = ___________ non-point source 19.) Answer = ___________ cost - benefit ...
*December 1, 2014*

**Rounding up and down**

Here is the rationale I gave for an earlier problem, for what it is worth :) ========================= Math - Damon, Monday, December 1, 2014 at 2:08pm to the nearest tens place 55 would be called 60 54.9999999999 would be 50 but 55.00000000001 would be 60 so if it starts with...
*December 1, 2014*

**Rounding up and down**

if <5, then 0 if 5 or more, then 10 .34 2. .351 ---> .4 .562 ---> .6 .545 ---> .5 whew .445 ---> .4 3. .351 --> .35 .562 --> .56 .545 --> .55 ***** .445 --> .45
*December 1, 2014*

**math....**

distributive property of multiplication -p(p) + -p(-q) + -p(8) = -p^2 + pq - 8p
*December 1, 2014*

**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*