Wednesday

September 2, 2015
Total # Posts: 21,878

**physics**

radial A = v^2/r tangential A = 7.9 they are perpendicular |A| = sqrt ( v^4/r^2 + 7.9^2 )
*April 17, 2015*

**Maths**

2/3 * 600 = 400 so 200 left after T shirt then 1/5 * 200 = 40 so 200 - 40 = 160 left to go home with
*April 17, 2015*

**math**

Any other line that intersects that one will do. It can not be the same line and it can not be parallel. You have -3 x + 2 y = 4 so change the sign of the x coefficient for example which changes the slope. +3 x + 2 y = 4 Now you have -3 x + 2 y = 4 +3 x + 2 y = 4...
*April 15, 2015*

**Pre - CALCULUS**

y = 5 x - 3 as x goes to 5 y ---> 22
*April 15, 2015*

**Physics**

Same answer as your other question.
*April 15, 2015*

**Physics**

eg: http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-007-electromagnetic-energy-from-motors-to-lasers-spring-2011/lecture-notes/MIT6_007S11_lec38.pdf
*April 15, 2015*

**Physics**

Google Heisenberg uncertainty principle certainty of product of position and momentum is limited so the more accurately you know position the less accurately you know momentum
*April 15, 2015*

**nope**

not without knowing the water temp at start
*April 12, 2015*

**physics**

power = voltage * current 20,000 * 50 = 500,000 i i = 50 (2/50) = 2 amps That is why you send big power at high voltage
*April 12, 2015*

**LINEAR EQUATIONS**

There is a limit to how many people I can help at once.
*April 12, 2015*

**LINEAR EQUATIONS**

c = a + b x or 100 = a + b(20) 122.5 = a + b(25) -------------------- 22.5 = 5 b b = 4.5 100 = a + 4.5*20 a = 10 so y = 4.5 x + 10 ----------------- now check if 25 wraps y = 4.5*25 + 10 = 122.5 sure enough
*April 12, 2015*

**Math**

However here the sum of any two must not be less than the third side or they will not reach b fails c fails d fails ONLY A passes :)
*April 12, 2015*

**math problem HELP ME**

Look at this scroll down to "algebraic proofs" http://en.wikipedia.org/wiki/Pythagorean_theorem
*April 12, 2015*

**math problem HELP ME**

(a-b)^2 + (4 a b/2) = a^2 - 2 a b + b^2 + 2 a b = a^2 + b^2 but as you know c^2 = a^2 + b^2 is the Pythagorean Theorem
*April 12, 2015*

**Math**

tan 40 = h/5 not much of a tree :)
*April 12, 2015*

**physics**

no your torque is not constant from 0 to 1 second it is Torque = 2 t for 0 to 1 second a = 2 t/2.5 v = (2/2.5)(t^2/2) = 1/2.5 rad/s at 1 second ------------------------ NOW that is your constant torque of 2 from 1 second to 2 seconds initial v = 1/2.5 rad/s a = dv/dt = 2/2.5 v...
*April 12, 2015*

**Vectors**

1) x = 1 + 2 s or s = (x-1)/2 y = 7 + 5 s y = 7 +(5/2)(x-1) 2y = 14 + 5 x - 5 5 x - 2 y = -9 now where does that hit 2) ? t = (x-3)/4 so y = (10/4)(x-3) + 12 4 y = 10 x - 30 + 48 10 x - 4 y = -18 so we have two equations 5 x - 2 y = -9 10 x - 4 y = -18 BUT THEY ARE the SAME ...
*April 12, 2015*

**physics**

Actually, I took the course in 1956 and do not need the practice. You do. Try and I am sure one of us will look your results over.
*April 12, 2015*

**math**

$1000 in and $400 out :) chance of winning = 1/500 value = 400/500 = 80 cents
*April 12, 2015*

**Algebra 1**

You are welcome.
*April 12, 2015*

**Algebra 1**

h = t (64-16 t) h is zero, ground, when t = 0 and when t = 4 t may not be - t may not be greater than 4 unless the arrow drops into a mine shaft so I would say 0</= t </= 4
*April 12, 2015*

**typo ?**

do you mean -16 t^2 + 16 t + 32 ???? all t, no x that in the obsolete foot, pounds, slugs units is the height of a projectile under gravitational force only. In that case 32 is the initial height in feet when t = 0
*April 12, 2015*

**Science**

thrust = rate of change of momentum mass per second in = 40 momentum per second in = 8000 mass per second out = 42 momentum per second out =42*600 = 25200 change of momentum per second = 17200 kg m/s^2 which is 17200 Newtons By the way, that is Newton #2 which you know better ...
*April 12, 2015*

**Physics**

Q = flow rate = pi r^2 V loses rho g h = 1000 kg/m^3 * 9.81 m/s^2 * 5.2 m in N/m^2 or Pascals it will go faster through the smaller pipe so loses pressure by Bernoulli Q2 = Q = pi r^2 V2 so V2/1.8 = 6.5^2/5.5^2 calculate V2 then pressure loss due to v increase is (1/2)(1000) (...
*April 12, 2015*

**Algebra 2 A**

y^2 + 6 y = 3 x - 3 y^2 + 6 y + 9 = 3 x + 6 (y+3)^2 = 3 x + 6 (y+3)^2 = 3 (x+2) vertex at (-2,-3) open to right
*April 12, 2015*

**Physics**

what is the period when the resonance occurs? T = distance/speed = 5 / 6.1 m seconds so frequency f = 1/T = 6.1/5 Now do your sqrt K/m thing
*April 12, 2015*

**Math**

hey ANY 2 dimensional figure if its scale is multiplied by x its AREA is multiplied by x^2 2^2 = 4 or in this case 2L * 2 w = 4 L w
*April 11, 2015*

**Math**

(4/3) pi r^3 = (4/3)pi(8) = 33.51 m^3 (1/3)(pi)(4)^2 (10) = 167.6 m^3
*April 11, 2015*

**Math**

3*36 + 2*12 + 8 = 140 inches (Sheila) 24*12 + 8 = 296 inches (record) =296-140 = 156 inches longer 156/12 = 13 feet longer
*April 11, 2015*

**algebra**

0/5 = 0 5/0 is very, very very big try on your calculator 5/ 0.00000001
*April 11, 2015*

**pre - CALCULUS**

34/5 + 11/5 + z = 9 ? z = 9 - 9 = 0 2 * 34/5 - 3 * 11/5 + 4z = 7 7 + 4 z = 7 z = 0 ah ha, B -7 z/5 + 2 z/5 + z IS ZERO LOL Talk about fooling the student !
*April 11, 2015*

**ah ha**

34/5 11/5 undefined 0 can not solve for z, bottom row all zero put arbitrary z in and see what happens
*April 11, 2015*

**pre - CALCULUS**

whoops, 2 not three in row 2 beginning put in +1 +1 +1 +9 +2 -3 +4 +7 +1 -4 +3 -2
*April 11, 2015*

**pre - CALCULUS**

Those answer choices are wrong
*April 11, 2015*

**pre - CALCULUS**

put in +1 +1 +1 +9 +3 -3 +4 +7 +1 -4 +3 -2 3 rows, 4 columns
*April 11, 2015*

**pre - CALCULUS**

0 , 29/7 , 34/7 it says http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*April 11, 2015*

**pre - CALCULUS**

strange answer choices, arbitrary z hang on
*April 11, 2015*

**pre - CALCULUS**

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx
*April 11, 2015*

**pre - CALCULUS**

But there is a limit to what I am going to try to type
*April 11, 2015*

**pre - CALCULUS**

oh ho, now Gauss Jordan. We are cooking with gas here
*April 11, 2015*

**Pre - CALCULUS**

LOL, I have not finished You need to do the whole ting all you know is termm 11 and 21 so far whoops 12 not +12 so element 11 is 5/12 and element 21 is -1/6 looks like C
*April 11, 2015*

**Pre - CALCULUS**

left determinant is D = -12 first solution is for +1 -6 +0 -5 or -5/12 = element 11 then +0 +1 -2 +0 over -12 or 2/-12 = -1/6 = A21 then do the second
*April 11, 2015*

**Pre - CALCULUS**

well, it may be time to ask what method you are supposed to use. for example you seem to have Cramer's rule so A * A*-1 = 1 0 over 0 1 so solve with 1 over 0 on the right then with 0 over 1 on the right so for first column of inverse solve +0 x - 6 y = 1 -2 x - 5 y = 0 ...
*April 11, 2015*

**Pre - CALCULUS**

I mean 9 :)
*April 11, 2015*

**Pre - CALCULUS**

+2 +4 -1 +1 -2 +2 ---> -4+40-1 -10-4-4 = 17 yuuk +5 +1 +1 now solve for Y not x because your solutions set has all different y values :) +2 32 -1 +1 -5 +2 ---> --10+320-20 -25-80-32 = 153 +5 20 +1 then 153/17 = ( whew, D
*April 11, 2015*

**pre - CALCULUS**

yes -4 * -1 = 1 and -4*3 = -12
*April 11, 2015*

**pre - CALCULUS**

note the determinant of 2 1 6 3 is 6 - 6 = 0 therefore the solutions using Cramer's Rule are undefined
*April 11, 2015*

**physics**

volume of iron = (4/3)pi (Rout^3-Rin^3) mass of iron = (1 g/cm^3)(4/3) pi Rout^3 so density of iron = Rout^3/(Rout^3-Rin^3)
*April 11, 2015*

**math**

18(4/3) = 24
*April 11, 2015*

**maths**

10^x * 10^y = 10^(x+y) (to multiply add exponents if the base is the same)
*April 11, 2015*

**NEED HELP PHYSICS!!!**

Ac = v^2/r = v^2/10.5 F = m Ac 3.22 = .0822 v^2 /10.5 solve for v
*April 11, 2015*

**PHYSICS HELP PLEASE !!**

F = m a tension = mg + m v^2/r F = 78.4 (9.81 + v^2/10)
*April 11, 2015*

**Calculus(urgent please help)**

vertical asymptotes is easy because x = 3 or -3 makes function undefined where is slope + and where - ? slope = ([x^2-9]2x - x^2[2x])/[x^2-9]^2 denominator is always + or 0 when is top + and -? top is -18x so slope = -18x/positive number so slope is + if x is + and - if x is...
*April 10, 2015*

**pre - CALCULUS**

You are welcome.
*April 10, 2015*

**pre - CALCULUS**

continuous A = P e^rt A = 11,000 e^(.065 *10) A = 11,000 * 1.9155 semiannual 20 periods at .0315 per period (6.3/2) 1.0315^20 = 1.859 A = 11,000 * 1.859 which is less :(
*April 10, 2015*

**Pre - CALCULUS**

well, I can not graph it very well but if exponential then y = Ae^kx x = year - 1985 12 = A e^0 = A(1) = A so y = 12 e^kx in 1994, x = 9 years y = 12 e^9k = 145 e^9k = 145/12 = 12 9 k = ln 12 = 2.48 k = .276 now in 2002 we would get x = 17 then we would get y = 12 e^(17*.276) ...
*April 10, 2015*

**Pre-calculus help**

tan is - in quadrants 2 and 4 cos is + in quadrants 1 and 4 so we are in quadrant 4, x = 6, y = -1 hypotenuse = sqrt (37) cute tan 2x = 2 tan x /(1-tan^2 x) = 2 (-1/6) /(1 - 1/36) =-(1/3) / (35/36) = -12/35 well that was easy now we better find out what quadrant 2x is in x is ...
*April 10, 2015*

**pre - CALCULUS**

so did I
*April 10, 2015*

**pre - CALCULUS**

Hey, I just did it.
*April 10, 2015*

**pre - CALCULUS**

to add two vectors you can add the components in orthogonal (perpendicular) directions and the sum will have components in those directions if u = a i + b j and v = c i + d j then u + v = (a+c) i + (b+d) j now here u+v = (-4+4) i + (1+1) j or 0 i + 2 j which is magnitude 2 in ...
*April 10, 2015*

**pre - CALCULUS**

I am not sure I understand your symbol. (absolute value?) anyway u + v = 2 j the magnitude of 2 j is 2
*April 10, 2015*

**Math 222**

Well, I told you number line eg so x is left of -3 or right of +2
*April 10, 2015*

**Math 222**

You are welcome.
*April 10, 2015*

**Math 222**

12 - x > 15 -x > 3 multiply both sides by -1 BUT change direction of arrow when changing signs x < - 3 (LOL - again) 7 x - 13 > 1 7 x > 14 x > 2 so x is left of -3 or right of +2
*April 10, 2015*

**Math 222**

divide it up into two problems 12 <12+ 4x 4 x >0 or x >0 and 12+4x <0 4 x < -12 x < - 3 so x is either left of -3 or right of 0 on a number line
*April 10, 2015*

**pre - CALCULUS**

The new graph has a point at (0,2), not at (0,0) The new graph has slopes of 2 and -2 instead of 1 and -1 in other words translate up[ 2 and double the slopes of the V shape
*April 10, 2015*

**pre - CALCULUS**

the point (2,2) (y must = x) becomes y = 2 |2| + 2 = 6 (y must equal 2 x+2) so (1,2) in the old graph becomes (1, 6) etc
*April 10, 2015*

**pre - CALCULUS**

no the point (1,1) becomes y = 2 |1| + 2 = 4 period, not 6 in other words (1,4)
*April 10, 2015*

**pre - CALCULUS**

f(x) = |x| is a V with point at origin and 45 degrees up in quadrants 1 and 2 move the whole thing up 2 and double the slopes try some points (0,0) ---> (0,2) (1,1) ---> (1,4) (-1,1) --> (-1,4) etc
*April 10, 2015*

**pre - CALCULUS**

theta +/- n (360) = theta so -404 + 360 = -44 which is indeed 44 degrees below the x axis in quadrant 4 ======================================== You could also call it + (360-44) = 316 counterclockwise from the x axis but if you are doing triangles for trig you would use that ...
*April 10, 2015*

**Calculus**

pi r^2 = 8 so r = 1.60 miles dA/dt = 2 pi r dr/dt yes, correct so 7.5 = 2 pi (1.6) dr/dt dr/dt = .748 miles/hr You used the area, 8 for the radius R
*April 10, 2015*

**Math**

Yes, you owe the principal of 2,000 plus the total interest which is 240
*April 10, 2015*

**math - plz help!!**

LOL, lots of ways but to reduce it to absurd: z = 3 5x - 4y = -z 2x + 7y = 5
*April 10, 2015*

**science ms sue plz help**

I agree with all your answers.
*April 10, 2015*

**physics**

Now Jhanvi, you are asking the same question over and over with slight changes. Figure out the time for each leg of your course. Figure out the total time by adding the times for each leg. Divide the total distance by the total time. That is your average speed.
*April 10, 2015*

**Maths**

a b c 55 times an integer 110 nope 165 nope 220 nope 275 SCORE!!!!!
*April 10, 2015*

**Physics**

by the way the relative density of steel is about 8
*April 10, 2015*

**Physics**

500 - 446 = 54 g = mass (not weight or force) of water displaced which is 54 cubic centimeters so density of block = 500 g/54 cm^3 = 9.26 g/cm^3 = 9260 kg/m^3 9260/1000 = 9.260 = relative density
*April 10, 2015*

**physics**

time at 80 t1 = 400/80 time at 100 t2 = 200/100 total time = t1 + t2 av speed = 600 / (t1+t2)
*April 10, 2015*

**physics**

look at my reply to your other problem, same way.
*April 10, 2015*

**math**

number of visitors can not be fractional therefore more than 31 and less than 33 31 < v < 33
*April 9, 2015*

**Calculus**

or more accurately i = 1000 e^kt 1200 = 1000 e^7k e^7k = 1.2 7 k = ln 1.2 k = .0260459367 as you said
*April 9, 2015*

**Calculus**

di/dt = k i di/i = k dt ln i = kt + c i = e^(kt+c) = C e^kt here 200/7 = k (1000) k = .02875 i = 1000 e^(.02875 t)
*April 9, 2015*

**Algebra**

(12x^5y^2z^3)/(9x^3y^3z) (9)(x)(y)(z)(12x^5y^2z^3)/(81 x^4 y^4 z^2) (108 x^6 y^3 z^4)/(9 x^2 y^2 z)^2 take sqrt 6 x^3 y z^2 sqrt(3y)/(9 x^2 y^2 z)
*April 9, 2015*

**Algebra**

in other words ^-12 a b^3 c^(7/6) a b^3 c^6/6 c^1/6 a b^3 c c^(1/6)
*April 9, 2015*

**Calculus**

e^-2y dy = 2 x dx e-2y /-2 = x^2 + c e^-2y = -2 x^2 + c -2y = ln (-2 x^2+c) when x = 0, y = 1 -2 = ln(c) e^-2 = c -2 y = ln (-2x^2+e^-2) y = -(1/2) ln(-2x^2+1/e^2)
*April 9, 2015*

**Math**

2^2 - 3 = 1 4^2 - 3 = 13 7^2 - 3 = 46 etc :)
*April 9, 2015*

**Calculus**

d^2x/dt^2 = -22 dx/dt = 132 - 22 t x = Xo + 132 t - (1/2)(22) t^2 so x to stop from 132 ft/s 0 = 132 - 22 t t = 6 seconds to get dx/dt = 0 then x = 132 (6) - 11 (36) x = 792 - 396 = 396 ft to stop so 4 feet to spare Now I think you can handle Robin';s unfortunate experience.
*April 9, 2015*

**science**

I believe so. Think what is happening. gravity on big mass squeezing center of mass harder and harder
*April 9, 2015*

**science**

You are welcome.
*April 9, 2015*

**science**

Yes, A elliptical is old stars, little gas or dust to make new ones. C and D are exactly wrong :)
*April 9, 2015*

**Calculus**

r-b = 8 r+b = 20 solve for r and b find r/(r+b) r-b = 10 r+b = 30 solve for r and b find r/(r+b)
*April 9, 2015*

**Math**

y = 10 + x/3 y + x = 46 so y = 46 - x 46 - x = 10 + x/3 36 = 4 x/3 x = 27 y = 46-27 = 19 ======================== 25 q + 10 d = 1205 d = 59 - q so 25 q + 590 - 10 q = 1205 etc
*April 9, 2015*

**science**

yes, sometimes one moves behind the other, masking the pair look dimmer
*April 9, 2015*

**math**

You are welcome :)
*April 9, 2015*

**math**

I said (1/5) x + 2 = x - 4 multiply everything both sides by 5 x + 10 = 5 x - 20
*April 9, 2015*

**math**

I do not know. Do you mean y=(1/5)x+2 y=x-4 then x + 10 = 5 x - 20 x = 30/4 = 15/2 = 7.5 or do you mean y = 1/(5x) + 2 then 1 + 10 x = 5 x^2 - 20 x solve quadratic or do you mean 1/(5x+2) = x-4 1 = (5x+2)(x-4) 1 = 5 x^2 + 18 x - 8 etc
*April 9, 2015*

**science**

I believe so.
*April 9, 2015*

**calc(steps and explanation also)**

D^2 = x^2 + y^2 2 D dD/dt = 2 x dx/dt + 2 y dy/dt or dD/dt = (x dx/dt + y dy/dt)/D at t = 0 x = 0 y = 150 at t = 10 x = 580 y = 150+100 = 250 D = sqrt(580^2+250^2) = 631.6 dx/dt = 58 dy/dt = 10 so plug into dD/dt = (x dx/dt + y dy/dt)/D
*April 9, 2015*

**math**

12 x - 3 = 2 x + 4 10 x = 7 x = 7/10 y = 2(7/10) + 4 y = 14/10 + 4 y = 5.4
*April 9, 2015*