Wednesday

October 1, 2014

October 1, 2014

Total # Posts: 18,728

**physics**

assume start from rest v = Vi + a t v = 0 + 3 * 10 which is 30 m/s
*July 31, 2014*

**physics**

distance = 820 + 600 time = 10.3 * 60 + 3.8 * 60 average speed = distance / time
*July 31, 2014*

**Mathh**

total cards = 110 + 75 + 315 gave away = 110 + 75 percent given = 100 (110+75)/(110+75+315)
*July 31, 2014*

**physics**

20 * 9.81 * .7 no work is done carrying. Force is not in direction of motion
*July 31, 2014*

**physics**

Vi - 8 t like DROSP said
*July 31, 2014*

**physics**

I might do it in m/s though .14 / 180 = 7.77 * 10^-4 m/s = .000777 m/s
*July 31, 2014*

**physics**

1 km/min = 60 km/hr
*July 31, 2014*

**physics**

water mills and wind mills ?
*July 31, 2014*

**physics**

5350 /(5350 + 600) multiply by 100 if you want percent
*July 31, 2014*

**math**

First one, roll 6 times p is a two = 1/2 p not a two = 1/2 p a two one out six rolls = (6,1) (6!)/[(1)!(5!)] (1/2)^1(1/2)^5 = 6 (1/2)^6 Second one p is a two = 2/3 p not a two = 1/3 p a two one out of 6 rolls = 6 (2/3)^1 (1/3)^5 = 6 (2)/3^6 P second one / p first one = 2/3^6 /...
*July 31, 2014*

**physics**

A (1/2) m v^2 B (1/2)(18m)v^2/9 B/A = twice
*July 31, 2014*

**physics**

Jill (1/2) m (100/15)^2 Jon (1/2) m (100/30)^2 Jill/Jon = 30^2/15^2 = 4 Jill's ke = 4 time Jon's
*July 31, 2014*

**physics**

10 cm * 1 meter/100 cm = 0.1 meters 120 * .1 = 12 Joules
*July 31, 2014*

**physics**

1*9.78 - 5 Does it really say g = 9.78 m/s and not g = 9.81 m/s^2 ???????
*July 31, 2014*

**physics**

Francis, read and punch calculator. He gave you the answer.
*July 31, 2014*

**math**

4 sqrt 6 ---------- sqrt (6*5) = 4/sqrt 5 * sqrt 5/sqrt 5 = (4/5) sqrt 5
*July 30, 2014*

**PreCalculus**

If the events are independent, you multiply the probabilities. For example that would not apply to falling and getting eaten by the shark BECAUSE you were hit by lightning or the ship sank but only as independent events.
*July 30, 2014*

**physics**

2.74 + 3.19 cos 61.2
*July 30, 2014*

**Math**

Mike (1/60) project/min Walter (w project/min) together (1 + 60 w)/60 project /min [(1+60 w)/60 ] 40 = 1 project 1 + 60 w = 6/4 60 w = .5 w = .0083333 1/w = min/project = 120 minutes
*July 30, 2014*

**ALGEBRA**

L = w + 3 (L+2)(w+2) = 70 + (L)(w) (w+5)(w+2) = 70 + (w+3)(w) w^2 + 7 w + 10 = 70 + w^2 + 3 w 4 w - 60 = 0 w = 15 L = w+3 = 18
*July 30, 2014*

**ALGEBRA**

approach speed = v + v+60 = 2 v+60 d = rate * time = (2v+60)(5) = 10 v + 300 unfortunately we were not given d, their distance apart so I am faced with a problem or a typo.
*July 30, 2014*

**maths**

Republican and Tea Party ?
*July 30, 2014*

**Math**

(100 pages / h hours) (1 hour/60 min) = (100/60 h) pages/min * m minutes = (100 m /60 h) Probably C but if so you have a typo
*July 30, 2014*

**calculus 2**

y = x^(1/3) ????? h = (6-1)/10 = . x____________ y 1____________ 1 1.5 _________ 1.145 2____________ 1.260 2.5__________ 1.357 3 etc etc etc 3.5 4 4.5 5 5.5 6 integral is about (.5/3)(y0+4y1+2y2+4y3 +2y4 ......+1y10)
*July 29, 2014*

**Physics**

Normal force = m g cos 30 max friction force = mu m g cos 30 power in = power out P = (mu m g cos 30) v
*July 28, 2014*

**Physics -- check answers please**

yes yes
*July 28, 2014*

**Physics**

-4 F (opposite charges attract)
*July 28, 2014*

**pharmacy**

huh? .930/3 = 0.310 mg
*July 28, 2014*

**Calculus**

easy way: r = (4/16) h = (1/4) h surface area = pi r^2 = pi (1/16) h^2 dV = surface area * dh dV = pi (1/16) h^2 dh DV/dt = (1/16) pi h^2 dh/dt hard way: V = (pi/3) r^2 h given again r^2 = (1/16) h^2 V = (pi/3)(1/16) h^3 dV/dh = (pi/16) h^2 again dV/dt = (pi/16) h^2 dh/dt
*July 27, 2014*

**math**

speed = s current = c s + c = 17.2 s - c = 10.4 ------------ add 2 s = 27.6 etc.
*July 27, 2014*

**Math**

Those are both straight lines, graph them. x - 3 y= 10 goes through (0,-10/3) and (10,0) we are on that line and left of it 3 x - 2y = 5 goes through (0,-2.5 ) and (5/3 , 0) we are on that line and below it where do they hit? 3 x - 9 y = 30 3 x - 2 y = 5 ------------------ -7 ...
*July 27, 2014*

**Physics 2**

speed of light is about 3 * 10^8 meters/ second by the way
*July 27, 2014*

**physics**

diffraction grating again
*July 27, 2014*

**physics**

y = m lambda D/d d bigger means y smaller
*July 27, 2014*

**physics**

less distance ---> more friction, more retarding force
*July 27, 2014*

**physics**

momentum before = 2 *.28 momentm after = 2 v + .5 * 1.5 .56 = 2 v + .75 2 v = -.19 v = - .095 (The Answer :) Now by the way is this possible? initial kinetic energy = (1/2)2 (.28)^2 = .0784 Joules final Ke = (1/2)(2)(-.095)^2 + (1/2)(.5)(2.25) = .009025 + .5625 = .5715 Joules ...
*July 27, 2014*

**calculus 2**

odd function from -3 to + 3 ---> 0 I suspect
*July 26, 2014*

**Algebra**

60 = L + 2 w so L = 60 -2 w A = L w A = (60-2 w)w = 60 w - 2 w^2 If you know calculus, just take derivative and set to zero and you are done If not, complete the square to find vertex of parabola. w^2 - 30 w = -A/2 w^2 - 30 w + 225 = -A/2 + 225 (w-15)^2 = -(1/2)(A - 450) so w...
*July 26, 2014*

**Physics**

When a wave travels from fast to slow medium: Reflected wave is inverted. (crest -reflected as trough is 180 deg phase shift)
*July 26, 2014*

**Algebra**

Sketch those lines slopes of +/- 1 center axis halfway between 1 and 5 so at y = 3 the lines cross at (2,3), so that is center of hyperbola so (x-2)^2/a^2 - (y-3)^2/b^2 = 1 slopes of asymptotes = +/- b/a so b = a (x-2)^2/a^2 - (y-3)^2/a^2 = 1 put that point in now (4-2)^2/a^2...
*July 26, 2014*

**Physics -- check answers please**

1. ok 2. We used to use a "diffraction grating" in the spectroscopy lab to get the clearest pattern.
*July 26, 2014*

**Calc**

Oh, sorry, I thought you meant just the length of that splitting fence.
*July 25, 2014*

**Calc**

.000000000000001 feet or perhaps the length of the width of a cow. :) The problem does not make much sense as stated. You could make the field extremely longs and not at all wide and divide it with a little fence in the middle the length of your very short ends.
*July 25, 2014*

**algebra 1**

well, do part B and you will have the answer to part A 100 - 1.9 = 98.1 percent so every time we go a meter, we multiply by .981 after x meters f(x) = 1700 * .981^x (Part B answer) which is exponential, not linear. (part A answer) It does not lose a constant "amount"...
*July 25, 2014*

**Calculus: Determine the constants from function**

dh/dx = 0 at critical points dh/dx = 3 x^2 + 2 b x = 0 x (3x+2b) = 0 so at (2,4), 3x+2b = 0 = 6 + 2b so b = -3 so h = x^3 -3 x^2 + d at x = 2, h = -4 -4 = 8 - 12 + d d = 0 so h = x^3 -3 x^2
*July 25, 2014*

**College Algebra**

^4t not to the t/4 1.01875^4t = 7200 4 t = log 7200/log 1.01875 t = 120 years
*July 25, 2014*

**Math 221**

That is: https://www.khanacademy.org/math/linear-algebra/vectors_and_spaces/vectors/v/linear-algebra--parametric-representations-of-lines
*July 25, 2014*

**Math 221**

Your talk of origins does not make a lot of sense to me since the origin is at (0,0) for all your problems. However perhaps your class is trying to work toward a vector version of this material where you specify a point and move out from there at a certain slope. In that case ...
*July 25, 2014*

**Math 221**

If y = x + 8 the x axis intercept for that is when y = 0 0 = x + 8 x = -8 so (-8,0) the y axis intercept for that is when x = 0 which is b in y = m x + b so 8 so at (0, 8) --------------------------------------- I thought I did that other one too. This time you did the problem...
*July 25, 2014*

**Math 221**

Go back, I just saw this below and replied. http://www.jiskha.com/display.cgi?id=1406309814
*July 25, 2014*

**MAth**

10 y^2 - 15 y + 2 y - 3 or 10 y^2 - 13 y - 3
*July 25, 2014*

**Physics**

I do not have your figure. HOWEVER (Note - I do not care what mass it is, call it m not 200 until part c) initial kinetic energy = (1/2)m(100) = 50 m Ke at any height h = 50 m + m g (100-h) so at any height h (Points A B and C) (1/2) m v^2 = 50 m + m g (100-h) note m cancels) ...
*July 25, 2014*

**math**

You are welcome.
*July 25, 2014*

**math**

n on shelf .5 n are #1 .25 * .5 n = .125 n are #3 .5 n + .125 n = .625 n are either #1 or #3 so 1 n-.625 n = .375 n = 5 n = 5/.375 = 13 1/3 hmmmm, I hope we have a fractional bookcase
*July 25, 2014*

**math**

so, like maybe they were 270 miles apart and collided at x pm :) they approach each other at 45 miles/hr 270 miles/45 miles/hr = 6 hours 6+5 = 11 pm
*July 25, 2014*

**science**

No, but note that they grow back after a few weeks ! http://birds.about.com/od/grooming/a/How-To-Clip-Your-Birds-Wings.htm
*July 25, 2014*

**Math 221**

typo yp should be y1
*July 25, 2014*

**Math 221**

Oh, I see what you are doing. given y = x + 4 we want parallel and through (-7,1) since y = 1 x + 4 has slope = m = 1 ANY parallel line ALSO has slope = 1 slope = 1 = (y-yp)/(x - x1) or 1 = ( y - 1 ) / (x - -7) 1 = (y-1) / (x+7) y-1 = x + 7 y = x + 8 I like my way better, but ...
*July 25, 2014*

**Math 221**

The origin is always at (0,0) However none of your lines go through the origin.
*July 25, 2014*

**Math 221**

yes I did not entirely follow all your steps though. The way I do it y = 1 x + 4 m = 1, so my new m must be 1 also if parallel ( I did not follow you here) point is (-7, 1) 1 = 1(-7) + b yes b = 8 y = x + 8
*July 25, 2014*

**do not understand**

I can not fathom your notation.
*July 25, 2014*

**Math 221**

assume you mean y = (-1/2) x + 1 slope m = -1/2 so slope of perpendicular = -1/m = 2 y = 2 x + b put in point 2 = 2(4) + b b = -6 so I agree y = 2 x - 6 You are getting these right but not the way I do them and I have not figured out what you are doing yet.
*July 25, 2014*

**Math 221**

I think I just did these above.
*July 25, 2014*

**math**

how many combinations of three from 5 n!/[ r!(n-r)! ] 5!/[2!(3!)] = 10 or do one by 1 the hard way A B - C, D, E --> 3 A C - D, E -->2 A D - E -->1 B C - D, E -->2 B D - E -->1 C D - A -->1 3+2+1+2+1+1 = 10
*July 25, 2014*

**Math**

I got 120
*July 24, 2014*

**Math**

Adults = .6 * 840 = 504 children = .4 * 840 = 336 504 = .7 (840 - boys)
*July 24, 2014*

**MATH**

profit = .2 S cost = 72 72 + .2 s = s 72 = .8 s s = 90 =============================== Javier had J = 28 28 + (4/5) D = 64 (4/5) D = 36 D = 45
*July 24, 2014*

**Math**

perimeter = 4 x so x = 15 area = 225 -------------------- A does task/r per day B does task/s per day [ 1/r + 1/s ] task/day together so 1/ [ 1/r + 1/s ] = r s / (r+s) or r s ------- r + s which is probably d) but you left the parentheses out
*July 24, 2014*

**statistic**

I can not see your problems. Copy and paste does not work here. However I am sure this link will do the trick anyway: http://davidmlane.com/hyperstat/z_table.html
*July 24, 2014*

**Math: Zeroes**

Oh, 50 factorial 50 * 49 * 48 ..... 1 3.0414093e+64 so 64 Just GOOGLE 50 factorial
*July 24, 2014*

**Math: Zeroes**

I would just write the list out if I could not guess :) You could shorten the task as so: 1 ----- 10 11 -----20 21 -----30 31 .....40 41 .....50 :-)> . .
*July 24, 2014*

**Chemistry**

you have two Mg for every one O2 so mols Mg/mols O2 = 2/1 3 mols Mg ( 1 mol O2 / 2 mols Mg) = 3/2 = 1.5 mols O2 ----- Yes 1 O2/2 MgO 3 O2 ( 2 MgO/1 O2 ) = 6 MgO
*July 24, 2014*

**typo**

By the way, if you happen to know Physics: v = Vi - 32 t at top v = 0 0 = 56 - 32 t t = 1.75 seconds 32 ft/sec^2 = acceleration of gravity in these obsolete units
*July 24, 2014*

**Math**

By the way, if you happen to know Physics: v = Vi - 32 t at top t = 0 0 = 56 - 32 t t = 1.75 seconds
*July 24, 2014*

**Math**

feet units drive me crazy but all right. 16 t^2 - 56 t - 1 = -h 16 t^2 - 56 t = - h + 1 t^2 - 3.5 t = - h/16 + 1/16 t^2 - 3.5 t + (3.5/2)^2 = -h/16 + 1/16 + 12.25/4 (t - 3.5/2)^2 = ...... vertex (top) when t = 3.5/2 = 1.75 seconds if they ask how high, keep going with ...
*July 24, 2014*

**Math**

2 x - 2 = x^2 - x - 6 x^2 - 3 x - 4 = 0 (x-4)(x+1) = 0 x = 4 or x = -1 y = 6 or y = -4 so (4,6) and (-1,-4)
*July 24, 2014*

**calculus**

well first of all it asked for the intercepts where does the first one hit the x axis? x (x^2 -6 x+ 9) = 0 x (x-3)(x-3) = 0 so x axis intercepts at x = 0 and x = 3 (twice which means that is a grazing or min or max of g Where does the first one hit the g axis? when x = 0, y = ...
*July 24, 2014*

**PhysicsI**

thickness = .005 meter Q =0.84 * Area * (delta T) /thickness = 0.84 * 1 * 15 /.005 Joules/second which is Watts by the way
*July 24, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*July 24, 2014*

**Geography**

A "dormant" volcano is one that has not erupted for a while and is not expected to do so in the near future. It is not "extinct" though and will probably erupt sometime in the future. See: https://www.google.com/search?q=dormant+volcano+definition&ie=utf-8&...
*July 24, 2014*

**Homework dumping**

There has been no sign of any effort by the student to do these problems.
*July 23, 2014*

**calculating statistical data**

Where is your attempt to solve these problems?
*July 23, 2014*

**Physics**

k Q1 Q2 / d^2 d2 = .5 d1 so d2^2 = .25 d1^2 1/.25 = 4 times like charges repel and for heavens sake READ THE BOOK !!!!
*July 23, 2014*

**I have no idea.**

Need volume of tank and volume of a carton
*July 23, 2014*

**science**

It is NOT MOVING (This is a trick question) total energy = (1/2) k x^2 = (1/2)(15.6)(.04)
*July 23, 2014*

**Maths.literacy**

Oh, I see, you asked question above assuming I had seen this one. volume of tank = pi r^2 L = pi (2.25)(3) meters cubed 1 kiloliter = 1 meter cubed However I do NOT know the volume of a carton of milk (perhaps one liter? Perhaps half a liter?)
*July 23, 2014*

**Physics**

L = I omega I = m r^2 = 90 * 40^2 omega = v/r = 5 /40 so L = 90 * 40^2 * 5 /40 = 90 * 200 = 18000
*July 23, 2014*

**mathematics**

first one fills 1 truck /12 min second fills 1 truck/6 min so together they fill (1/12 + 2/12) trucks per min which is 1/4 of a truck per minute or four minutes per truck. Get it?
*July 23, 2014*

**math**

bought x gallons dining room = (x/3) gallons kitchen = 1.5 gallons living rm = 3 gallons leftover = 1.5 gallons so (x/3) + 6 = x 6 = 2 x/3 x = 9 gallons
*July 23, 2014*

**something wrong here I think**

You have over defined this problem. Once you say 23.5 meters in 5 seconds you have set the horizontal speed u = 23.5/5 Now if you set the angle at 35 then u = initial speed * cos 35 so solve for the initial speed However now we have a dilemna. Vi = initial speed up = initial ...
*July 23, 2014*

**algebra**

Hey, I did one, your turn :)
*July 22, 2014*

**math**

3^5 + ***** 3^4 (bx) + ****** 3^3 (bx)^2 + ........ now get binomial coefficients for fifth power from Pascal's triangle or formula 1 5 10 10 5 1 so 3^5 + 5*3^4 b x + 10 * 3^3 b^2 x^2 243 + 405 b x + 270 b^2 x^2 ......
*July 22, 2014*

**calculus**

Nor do I
*July 22, 2014*

**calculus typo**

y = x^(2/3) at x = 1 which is b y = 1^(2/3) = 1 at x = 0 which is a y = 0^0 = 0 y(1) - y(0) = 1 - 0 = 1 b - a = 1 - 0 = 1 so 1/1 = 1 so according to the mean value theorem somewhere between x = 0 and x = 1 the derivative = 1 dy/dx = (2/3) x^-1/3 = (2/3)/x^(1/3) when is that ...
*July 22, 2014*

**calculus**

y = x^(2/3) at x = 1 which is b y = 1^(2/3) = 1 at x = 0 which is a y = 1^0 = 1 y(1) - y(0) = 1 - 0 = 1 b - a = 1 - 0 = 1 so 1/1 = 1 so according to the mean value theorem somewhere between x = 0 and x = 1 the derivative = 1 dy/dx = (2/3) x^-1/3 = (2/3)/x^(1/3) when is that ...
*July 22, 2014*

**Calculus**

y = 2 (x+5)^3 + 7 to make this really easy you can say z = x+5 then dz/dx = 1 y = 2 z^3 + 7 dy/dz = 6 z^2 d^2y/dz^2 = 12 z so dy/dx = dy/dz * dz/dx = 6(x^2+10x+25) when is that zero ? (x+5)(x+5) = 0 x = -5 twice what is d/dx (dy/dx)? 6 ( 2 x + 10) when x = -5 2(-5)+10 = 0 so ...
*July 22, 2014*

**physics typo**

physics - Damon, Tuesday, July 22, 2014 at 4:37am Newton #1 - If there is no NET force, momentum is constant. Here speed is steady (I assume in a straight course) and mass is constant so net force is zero. Newton #3 - Action is equal and opposite to reaction. So Propulsion ...
*July 22, 2014*

**physics**

Newton #1 - If there is no NET force, momentum is constant. Here speed is steady (I assume in a straight course) and mass is constant so net force is zero. Newton #2 - Action is equal and opposite to reaction. So Propulsion force forward must be equal and opposite to ...
*July 22, 2014*

**Math 221*revised***

You can enter that as 5' 2" in the web site I gave you: http://www.mayoclinic.org/bmi-calculator/itt-20084938
*July 22, 2014*

**Math 221**

http://www.mayoclinic.org/bmi-calculator/itt-20084938 You need male or female and birth date.
*July 21, 2014*

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