Saturday

December 3, 2016
Total # Posts: 28,237

**physics**

http://www.jiskha.com/display.cgi?id=1461575534

*April 25, 2016*

**Physcis**

How many Joules are needed? power = Vi = 110*7 = 770 watts energy = power*time = 770*600seconds 462,000 JOULES needed = m g h = m (9.81)(10) so m = 4709 Kilograms of water there are 1000 kg of water/meter^2 so 4.709 cubic meters of water

*April 25, 2016*

**Algebra I DONT KNOW HOW TO DO 3 VARIABLES**

x = 2 - y - 5z 4(2 - y - 5z) -3y + 5z = 3 3(2 - y - 5z) -2y + 5z = 1 8 - 4y - 20z - 3y + 5z = 3 6 - 3y - 15z - 2y + 5z = 1 -7y - 15z = -5 -5y - 20z = -5 or y = 1 - 4z -7(1-4z) - 15z = -5 7 + 28z -15 z = -5 13 z = 2 SO I get: z = 2/13 y = 13/13 - 8/13 = 5/13 x = 26/13 - 5/13 -...

*April 25, 2016*

**Physics help**

Is this the same set of waves? Do you have a box where you store leftover waves? If waves go by you in deep water with high speed and long wavelength for example, they will slow down and become shorter as they approach a shallow beach. However the same number hit the beach per...

*April 24, 2016*

**Math**

m = k n/p^2 3 = k (2/1) k = 3/2 m = (3/2) n/p^2

*April 24, 2016*

**Math, algebra 2**

arithmetic sequence first term is one so a = 1 d = -1 sum =120 see http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

*April 24, 2016*

**math**

5/4 inch * 4 miles/inch = 5 miles (ignoring the change in altitude :)

*April 24, 2016*

**math**

4 + 5 + 4 = 13 unless you mean (x+20) / (x+4) which is 24/8 = 3 watch your mathematical grammar.

*April 24, 2016*

**life orientation ?**

Is it a violation of my human rights to be asked the same question time after time, day after day, week after week until I am ready to scream?

*April 24, 2016*

**maths**

a, ar ar^2 ar^3 ar^4 a r^2 + a r^3 = -4/3 a r^3 + a r^4 = -4/9 a r^2 (1 + r) = -4/3 a r^3 (1 + r) = -4/9 -4/(3 a r^2) = -4/(9 a r^3) so r = 1/3 a(1/9)(4/3) = -4/3 a = -9 so: -9 -3 -1 -1/3 -1/9 and -1/27

*April 24, 2016*

**maths**

to get -1 + 0 i z^5 = 1 cos 180 + i sin 180 That should get you started

*April 24, 2016*

**math**

9+3 8+4 7+5 6+6 and reverse

*April 24, 2016*

**precalc**

θ = 180 + cos^-1 (1/3) = 180 + 70.5 = 250.5 ϕ = 180 - sin^-1 (1/4) = 165.5 so we want tan (416) = 1.48

*April 24, 2016*

**Calculus**

I get d^2s/dt^2 = 4 sin 3 t ds/dt = v = -(4/3)cos 3 t + c when t = 0 , v = 1 1 = -4/3 + c c = 7/3 v = -(4/3)cos 3 t + 7/3 s = -(4/9) sin 3 t + 7 t/3 + k 6 = k s = (1/9)(21 t - 4 sin 3 t +54)

*April 24, 2016*

**algebra**

1/R = 1/R1 + 1/R2 or R = R1 R2 /(R1+R2) = 8*12/(20) = 4.8 Ohms

*April 24, 2016*

**math**

L = k m^(1/3) 15 = k (125)^(1/3) = k (5) k = 3

*April 23, 2016*

**converting parabolic equations**

huh? multiply x + 15= 8(y^2 - 2y + 1) 8 y^2 - 16 y + 8 = x +15 x = 8 y^2 - 16 y -7

*April 23, 2016*

**Mathematics**

maybe something like let z = ln x dz /dx = 1/x dx = x dz ∫ 1/[x(1+lnx)^2] dx ∫ dz/[ 1+z]^2

*April 23, 2016*

**World History**

Even without an invasion or nuclear bombs Japan was all done. Between the American submarine fleet and surface/air fleets, they were being strangled. Japan does not have oil or many other vital supplies. Without merchant ships to and from Southeast Asia and elsewhere, they ...

*April 22, 2016*

**Math**

Oval? If it were circular, the fence would be 2 pi R long where R is radius (in feet, three times radius in yards) If it is an ellipse, then a = half length of long axis b = half length of short axis Perimeter = 4 a E(k) where k^2 = 1 - (b/a)^2 and E(k) is an elliptic integral...

*April 22, 2016*

**Complex number cartesian form**

Well, that was entertaining :)

*April 22, 2016*

**Complex number cartesian form**

yes r^2 = 4 + 4 = 8 so r = sqrt 8 = 2 sqrt 2 - 2 - 2 i is in quadrant 3, 45 degrees below -x axis Theta = pi + pi/4 = 5 pi/4 or 180 + 45 = 225 degress so x = 8^.5 e^(5 pi i/4) now raise to power five raise (8^.5)^5 = 8^2.5 multiply angle by 5 25 pi/4 = 24 pi/4 + pi/4 which is ...

*April 22, 2016*

**Math**

-4 = x^2 - 4 x = 0 then y = -4 A

*April 22, 2016*

**Physics**

1. U = (1/2) k x^2 =(1/2)(3.792*10^2) (1.42^2)(10^-2) = 3.82 Joules 2. same 3.82 Joules 3. 3.82 + m g h = 3.82 + .294(9.81)(0.960) = 6.59 Joules 4. How long does it take to fall .96 meters? .96 = (1/2)(9.81)(t^2)

*April 22, 2016*

**algebra!!!!**

do you mean y = x^2 - 2 x - 6 ???? if so then 4 x + 10 = x^2 - 2 x - 6 x^2 - 6 x - 16 = 0 (x-8)(x+2) = 0 x = +8 or x = -2 C is looking good but check it if x = -2 does y = +2 work? yes if x = +8 does 42 work? looks good so C

*April 22, 2016*

**Technology**

Hard to say. If you tried to copy and paste, that does not work here.

*April 22, 2016*

**Precal**

log x + log (x-3) = 1 log (x^2 -3x) = 1 10^log (x^2 -3x) = 10^1 = 10 x^2 -3 x -10 = 0 (x-5)(x+2) = 0 x = +5 or - 2

*April 22, 2016*

**Physics**

a) m g h = 110 * 9.81 * 200 Joules (you left the mass out) b) m g h = (1/2) m v^2 c) The work done by gravity is the same, force of gravity times distance down. The work done by friction makes the kinetic energy (speed) less at the bottom. It does not change the change in ...

*April 22, 2016*

**already know how**

I see a long string of what seem to be standard end of semester questions and I am being asked to do them despite having done so half a century ago. I see no attempt by the student or students to do the problems or any indication of what the difficulty is. All I see is an ...

*April 22, 2016*

**College Algebra**

v = Vi c^t .692 = c^3 c = .692^(1/3) c = .884 every year the car loses (1-.884) = .116 or 11.6% of its value value = initial value * .884^t

*April 21, 2016*

**Math**

9:45 do you not have a clock?

*April 21, 2016*

**math**

a lot of different things for example 6 (4+4) = 24 + 24 = 48 (2+2+2)(8) = 16 + 16 + 16 = 48 (1 + 5)(2 + 6) = 1(2+6) + 5(2+6) = 8 + 5*8 = 8 + 40 = 48 etc etc etc etc .......

*April 21, 2016*

**Geometry**

so divide your 85,403 by 9 9,489

*April 21, 2016*

**Math**

(1/2)(4/3)pi r^3 a little bigger than (2)(4^3) 2 * 64 128 a

*April 21, 2016*

**english**

Both are correct. The first means she has it now. The second means she had one in the past.

*April 21, 2016*

**english**

The police on the street and even the courts seem to employ different interpretations of the "innocent until found guilty" principle depending on the race of the suspect.

*April 21, 2016*

**math- pre calc**

x is negative in Q 2 (n/13)^2 + (5/13)^2^2 = (13/13)^2 12=n so x = 12/13

*April 21, 2016*

**HELP PHYSICS PLS :)**

In an elastic collision energy is conserved. NOT if it is inelastic. What is conserved in both cases is momentum. The total kinetic energy at the bottom = (1/2) m v^2 where m = 2.1 + .015 = 2.12 kg so your PE at top = (1/2)(2.12)v^2 solver for that v at the bottom. Then use ...

*April 20, 2016*

**Physics**

constant speed means no acceleration F = m g = 608 N W = force * distance = 608*4*5 = 12,164 Joules same but force opposite to motion for gravity -12,164 signs reverse if going down

*April 20, 2016*

**math**

3 x^3 (x-2)

*April 20, 2016*

**math**

if a circle of radius r then pi r^2

*April 20, 2016*

**Physics**

total R = 28 so i = EMF/28 = 1.5 so EMF = 1.5*28 = 42 volts voltage drop internal = 1.5*3 = 4.5 volts so terminal V = 42 -4.5 = 37.5 volts power waste = i^2R = (1.5)^2 * (3) = 6.75 Watts

*April 20, 2016*

**Math**

a + (3a+12) = 90 4 a = 78 a = 19.5 degrees 90 - 19.5 = 70.5 check 3(19.5) + 12 = 70.5 ok

*April 20, 2016*

**math help pls pls pls**

at x = 4 h = -16 +32 + 2 = 18 ft at x = 1 h = -1 +8 + 2 = 9 ft so from x = 1 to x = 4, the water went up 9 feet the average speed = 9/3 = 3 feet/second so yes c

*April 20, 2016*

**ethics**

My cat pretty much decides what he is going to do next.

*April 20, 2016*

**Physics**

if speed o sound = V meters per second then 2 V

*April 20, 2016*

**science help PLS**

Yes, the first choice is most likely.

*April 20, 2016*

**Maths**

conditional: If a cow, then a mammal Draw a small circle with a cow in it completely inside a big circle with other mammals in it. Alligators and dinosaurs are way outside even the big circle converse: If a mammal, then a cow (maybe, false) In big circle, maybe not in little ...

*April 20, 2016*

**nah**

0.00

*April 20, 2016*

**Analytic Geometry**

http://www.youtube.com/watch?v=8A1BsHbXWBE latus rectum: http://www.emathzone.com/tutorials/geometry/length-of-latus-rectum-of-ellipse.html

*April 20, 2016*

**Physics**

A) (1/2) m v^2 B) m g h Potential

*April 20, 2016*

**Algebra**

for heavens sake it says to subtract, so subtract 9-5 = 4 2 - 0 = 2 -5 - -7 = 2 4-4 = 0 so 4 x^3 + 2 x^2 + 2 x 2x(2x^2 + x + 1)

*April 20, 2016*

**Math**

You are welcome.

*April 20, 2016*

**Math**

yes, 2 pi r is a bit more than 6*12

*April 20, 2016*

**Math**

You want me to find the mean then the difference of each from the mean then square that then add them all and divide by 3 or 4 depending on your class' definition then take the square root. No way - You do it.

*April 20, 2016*

**good grief !**

Where? Silk road? European river routes? Indian Ocean? Baltic - Volga - Caspian - Black Sea? South China Sea? Mediterranean Sea?

*April 20, 2016*

**Maths**

e^iT = cos T + i sin T = for z^5 = -1 z^5 = 1cos pi + i sin pi that pi angle gives you real pat of -1 and imaginary part of 0 |z|= r = 1^(1/5) = 1 T = pi pi + 2pi/5 pi + 4pi/5 pi + 6 pi/5 pi + 8 pi/5 subtract 2 pi if they are over to get angles the first one is at 180 deg the ...

*April 20, 2016*

**Math**

60 = 5 * 2 * 3 * 2 60 = 2^2 * 5^1 * 3^1 log3(60)=log3(3)+log3(5)+2log3(2) we know log3(3) = 1 so log3(60) = 1 + x + 2y

*April 20, 2016*

**missed - sign**

5 a *c + 5 a *2b - 5 a *5d = 5 a ( c + 2b - 5d )

*April 20, 2016*

**Mathematics grade 9**

8m-24mn m is common and 24 = 8 * 3 so 8 m * 1 - 8 m * 3n = 8m ( 1-3n) 30gh+15fg-5fh 5 again and I see nothing else common to all three terms 5 ( 6gh + 3fg - 1fh )

*April 20, 2016*

**Mathematics grade 9**

5 a *c + 5 a *2b + 5 a *5d = 5 a ( c + 2b + 5d ) by distributive property of multiplication

*April 20, 2016*

**Pre-Cal**

by the way surely they ask the range, x x = u * t in air = 131 * 3.07 = 402 ft That is a serious throw

*April 20, 2016*

**Pre-Cal**

typo you mean y=h+v(o)tsin(o)-16t^2 Vi = initial speed up = 139 sin 20 = 47.54 ft/s u = horizontal speed = 139 cos 20 = 131 ft/s x = 131 t y = 5 + 47.54 t - 16 t^2 when is y = 0? 16 t^2 - 47.54 t - 5 = 0 t = [ 47.54 +/- sqrt(2260+320)]/32 use positive time t = 3.07 seconds in ...

*April 20, 2016*

**Math**

2 D correct 3 B correct despite the name being radiator the warm air will rise on the hot wall and sink on the cold wall. 4. D correct

*April 20, 2016*

**Massive typo**

There is no such thing as convention of heat. Perhaps you mean convection. You have it in all your choices I give up.

*April 20, 2016*

**algebra**

c = 2000 + .02 x

*April 20, 2016*

**Physics**

work = m g h = 63.9 * 9.81 * 0.16 * 135 Joules power = work/time here time = 5*60+40 seconds Kjoules = Joules work/1000 food calories = KJoules *(1 Cal/4.1868 Kj)

*April 19, 2016*

**Physics**

Trig, not physics Note they gave you math class angle measured north of east (counterclockwise from x axis), not compass angle as used by navigator or physicist. east 110 cos 25.1 north 110 sin 25.1

*April 19, 2016*

**Calculus I**

dy/dx = 3 ax^2 when x = 4, dy/dx= 48 a = slope but y = 4 x + b has slope of 4 so 48 a = 4 a = 4/48 = 1/12 and y = (1/12) x^3 when x = 4 y = 16/3 -4(4) + 16/3 = b -16 + 16/3 = b b = -32/3 so

*April 19, 2016*

**U.S. History (Check)(REED)**

A: The Pearl Harbor attack was so devastating for America because most of the U.S. Navy was destroyed and 2,403 Americans were killed. ---------------------- Well, most of our battleship navy in the Pacific was destroyed. I agree with your answers, and believe it or not I was ...

*April 19, 2016*

**Chemistry**

What is solubility ****

*April 18, 2016*

**Chemistry**

The molar solubility of a generic substance, Mg(OH)2 ksp = (1.2x10^-11) in 0.10 M NH3 Kb = 1.8 x 10^-5 help me please =)

*April 18, 2016*

**Math**

16 t^2 -112 t +160 = 0 t^2 - 7 t + 10 = 0 (t-5)(t-2) = 0 so at 2 seconds on the way up and at 5 seconds on the way down 0 = 16t (7 - t) crash at t = 7

*April 18, 2016*

**typo**

None of your answers are remotely close to what you asked.

*April 18, 2016*

**Calculus**

f^-1(x) definition is usually the inverse function if y = 7x + 3cos(x) + 2sin(x) substitute x for y and y for x and solve for y x = 7 y + 3 cos y + 2 sin y if x = 2 we want x = 2 2 = 7 y + 3 cos y + 2 sin y y better be in radians y x 0, 3 pi/6 , 7.26 -pi/6 , -.067 - pi/12 , +....

*April 18, 2016*

**Math**

first of all get your notation straight. Use ^ for exponents. Second follow the rule that Collins gave you (sort of): a^b/a^c=a^(b-c) and a^b a^c = a^(b+c)

*April 18, 2016*

**life orientation**

Torturing the teachers with the same question over and over without trying to do the assignment, three times.

*April 18, 2016*

**physics**

If it is perfectly inelastic, no bounce at all, then they are stuck together after the collision and all the momentum is in one 6 kg mass 4*3 - 2*2 = 6 * v before ke = (1/2)(4)(9) + (1/2)(2)(4) after ke = (1/2)(6)v^2

*April 18, 2016*

**Math**

16,000 + .1 s = 20,000 + .03 s .07 s = 4,000 s = 400,000/7

*April 18, 2016*

**Calculus -- Typo?**

the area ABOVE? y = 12??? That is infinite as is the area below y = sin x. There is no "between " I can see here.

*April 18, 2016*

**Geometry**

tan 58 = (84-6) / x

*April 17, 2016*

**english**

Well it is correct English. Of course it is nonsense.

*April 17, 2016*

**Math**

.06 x + .11(35,000 + 4x) = 66350

*April 17, 2016*

**English**

prices rise a lot quickly 4 is all right. 2 and 3 do not sound right.

*April 17, 2016*

**math**

z = (x - mean)/ sigma z = (80 - 70)/15 = 10/15 = 2/3 = .666666666666667 :) If there is more, use http://davidmlane.com/hyperstat/z_table.html

*April 17, 2016*

**logic**

http://amarvk.blogspot.com/2014/06/he-sits-between-two-mats-and-his.html

*April 17, 2016*

**Life orientation**

You can think of three.

*April 17, 2016*

**World History**

Perhaps it will become unpopular? There seems to be no monotonic trend in that direction though.

*April 17, 2016*

**Math**

1. arithmetic sequence with a = 8 and d = -9 2. geometric series with first term -2 and ratio r = 6 3. geometric again r = (1/9) hey http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html http://www.mathsisfun.com/algebra/sequences-sums-geometric.html

*April 17, 2016*

**Math **

maybe you mean 2^2 * 2^8 which is 2^10 = 1024 so If I am guessing right about your incomprehensible notation your sister is correct.

*April 17, 2016*

**Physics**

25 = (10/2) t t = 5 seconds to stop a = 10/5 = 2 m/s^2 up F = m a T - m g = m * 2 g = 9.81 so T = 800 (11.81) Newtons

*April 17, 2016*

**no**

=Cx+0.08x14.50 is wrong, very wrong. Try C(x) = .08 x + 14.50 C(40) = .08 (40) + 14.50 = 3.20 + 14.50

*April 17, 2016*

**interest**

.05/12 = .004166667 100 ( 1.004166667)^120 = $164.70

*April 17, 2016*

**interest**

100 (1.05)^10 = $ 162.89

*April 17, 2016*

**Physics**

.25 v = .25 (v/2) + .25 (2) .125 v = .5 v = 4 m/s

*April 17, 2016*

**Math**

C drives for 3 hours to meet M M drives for 2.5 hours to meet C Distance C = 60 * 3 = 180 Distance M = s(2.5) = 2.5 s but we know 180 = .8 d so d = 225 (not 500) distance M = .2 (225) = 45 miles so s = 45/2.5 = 18 mph =================== check 60 * 3 = 180 18 * 2.5 = 45 total ...

*April 17, 2016*

**Math **

student does not know how to type exponents This means 2^2 * 2^8 which is 2^(2+8) or 2^10

*April 17, 2016*

**Algebra**

a = 3 b c = 5 b a + b + c = 72 3 b + b + 5 b = 72 9 b = 72 b = 8 so a = 24 and c = 40

*April 17, 2016*

**Math 4**

20 / 705

*April 17, 2016*

**Math 3**

w(w+2) = 5 w^2 + 2 w - 5 = 0 ( w = [ -2 +/- sqrt (4 + 20) ]/2 w = -1 +/- .5 sqrt 24 have to use the + sign w = 1.45 L = 3.45

*April 17, 2016*