Saturday

April 19, 2014

April 19, 2014

Total # Posts: 16,161

**Physics**

CHECK MY ARITHMETIC !!! It came out awful coincidental though.

**Physics**

initial momentum = m V1 + 3m V2 final momentum = 4 m V3 same final momentum as initial so V3 = (V1+3 V2)/4 initial Ke = .5 m( V1^2 + 3 V2^2) final Ke = .5 (4m) (V3^2) = 2 m(V3^2) = 4 (.5m)V3^2 so change = .5m (V1^2+3V2^2 - 4 V3^2) but V3^2 = (V1^2 + 6V1V2 + 9V2^2)/16 4 V3^2 = ...

**math**

9 kilometers in 60 minutes = 9 kilometers/ hour

**Science asap**

1) B 2) condense = vapor to liquid evaporate = liquid to vapor both phase changes to precipitate is just to fall, not to change state.

**Science asap**

three states: ice , water , gas(water vapor) which has two of them ?

**Physics**

ok, that is may angle A so plug sin 59.2 and cos 59.2 in but check my algebra first

**Physics algebra error**

T = m(9.81)/cos A T sin A = m Ac = m v^2/R where R = 18 sin A so m (9.81) sin A/cosA = m v^2 /(18 sin A) v^2 = 9.81 * 18 * sin^2 A/cos A check my arithmetic !!!

**Physics**

I do not know where your angle is If from straight down then: T = tension m g = weight A = angle from vertical vertical equation T cos A = m g = m(9.81) so T = m(9.81)/cos A T sin A = m Ac = m v^2/R where R = 18 sin A so m (9.81) sin A = m v^2 /(18 sin A) v^2 = 9.81 * 18 * sin...

**Chemistry**

although what Steve said is fine.

**Chemistry**

Ferrous Nitrate (Iron+2) Fe(NO3)2 Ferric Nitrate (Iron +3) Fe(NO3)3

**English**

I suppose he could be any of us and what is he supposed to do about it anyway? It is those around him who reveal themselves ;) ( I am a physicist, not an English teacher, so you should ignore what I say )

**Physics**

71 kg = volume displaced * 1000 kg/m^3 so V = 71/1000 m^3 area * delta h = volume = 71/1000 2.34 * delta h = 71/1000 delta h = 30.34 /1000 in meters = 30.34/10 in cm = 3.03 cm

**help with math!!!!**

You should be able to do them yourself now.

**help with math!!!!**

Do not do it the way I did it. Use substitution, but you should get the same answer.

**help with math!!!!**

13. -x + y = -13 3x - y = 19 --------------- too easy to add them 2 x + 0 = 6 x = 3 y = -10

**help with math!!!!**

13. -x + y = -13 3x - 1 = 19 Is that a typo? No y in second equation? That sure makes it easy. 15. y = (7 x + 5) x - 3(7x+5) = 5 x - 21 x - 15 = 5 -20 x = 20 x = -1 y = -2 17. y = (-3x - 13) -2x + 5 (-3x-13) = -54 or 2x + 5 (3x+13) = 54 17 x + 65 = 54 17 x = - 11 x = -11/17 y ...

**Geometry**

by similar triangles divide hypotenuse into x and 29-x x/10 = 10/(29-x) 100 = 29 x - x^2 x^2 -29 x + 100 = 0 (x-25)(x-4) = 0 so the little triangle has short arm 4 and the big one has long arm 25 sqrt (100 + 16) = sqrt(116) = 2 sqrt(29) sqrt (100+625) = sqrt(725) = 5 sqrt(29) ...

**physics**

momentum = 3 (2) + 18 (0) = 6 before and after so 6 = 3 (u) + 18(v) or 2 = u + 6 v so u = (2 - 6 v) = 2 (1-3v) Ke same before and after: so 3(2^2) = 3u^2 + 18v^2 12 = 3(4)(1-3v)^2 + 18 v^2 2 = 2 (1 - 6v +9 v^2 ) + 3 v^2 0 = -12 v +18 v^2 + 3 v^2 21 v^2 = 12 v 21 v = 12 v = 12/...

**Science 6th grade Earth's day and night ANSWERS**

By the way, many would consider volcano eruptions destructive but for example they constructed the Hawaiian Islands and many other island and mountain chains.

**Science 6th grade Earth's day and night ANSWERS**

I agree with the answers as well.

**help i have no idea!!!!!!**

I assume you mean Amelia and not the rest of our family. She was a woman in a field dominated by men. It was even a struggle getting to learn to fly for a woman then. She was the ultimate "tomboy". Her parents got divorced, her father died of cancer.

**6th grade math**

The median gives you sort of a middle where half are above and half below. Use the median because Zimbabwe, Canada, and the US are not representative. As you can see, Zimbabwe pulls the average way down but is really what is often called an "outlier".

**Math ( trig )**

bottom of wheel up 5 so height above wheel bottom = 40 distance below center = 47 -40 cos A = 7/47 A = 81.4 degrees

**social studies(updated answers)**

I do not agree with your answers.

**S.S redo**

By the way, Google Vancouver Island and Fraser River gold rush.

**S.S redo**

Well, I agree with 10 and 12. 8 I am not Canadian, but did they not grow grain there? 9 is missing cod fish so I guess I would settle for water and wood. 11 read that again. You can not be serious.

**S.S redo**

1d 2c 3b 4a 5b 6b 7c I agree with those.

**computers**

If I replace 1/5 every year that is 100/5 = 20%

**Science**

No, if you decease the area then the force per unit area, called "the pressure", goes UP.

**Math ~ Check Answers ~**

I did not read it carefully.

**Whoa ! No**

23/92 = .25 .25^3 = .015625 .015625 * 240 = 3.75 ft^3

**Math ~ Check Answers ~**

yes, 60 was correct

**Math ~ Check Answers ~**

If it is similar, then ALL the dimensions, not just the height, are doubled. If you double lengths, you quadruple areas A = k L^2 90 * 4 = 360 in^2

**MATH**

x^2 - 4 x - 8 = 0 x = [ 4 +/- sqrt (16+32) ]/2 x = [ 4 +/- 4 sqrt 3 ] /2 x = 2 [1+/- sqrt 3 ]

**its my first day here in JISKHA QUESTION**

When I scroll down I see two questions of yours with replies.

**HELP JUST GIVE ME THE ANSWER A,B ,C, OR D**

Having made a living as a lobster fisherman at one point in my life, territory is everything.

**Physics**

force = change in momentum/time = m a if m constant Force * time = change in momentum F * 5 = 1400 * 25 F = 1400 * 5 = 7000 Newtons

**Physics**

1) true if stopped 2) yes max Ke at min height 3) Huh? It is true the normal force does not do work, but the friction force does so mechanical energy is LOST to heat. That is why it ends up lower and has to be towed back up to the start. 4) Well, this is true only if you defin...

**Physics**

- 3000 (719) Joules

**math/algebra**

This was actually just like the last one. It is your turn to do them now. I already passed the course.

**math/algebra**

x+z = 1 so z = (1-x) 2 x + 1 y = 1.5 so y = (1.5 - 2x) x + y + z = 0.5 so x + (1.5-2x) + (1-x) = 0.5 x + 1.5 - 2x +1 - x = 0.5 -2 x + 2.5 = 0.5 2 x = 2 x = 1 etc

**math/algebra**

z = (2-x) y = (3-x) x -(3-x) +(2-x) = 1 x - 3 + x + 2 - x = 1 x - 1 = 1 x = 2 z = 0 y = 1

**Math**

You are welcome :)

**Math**

20 k = 1980 k = 99 yes correct

**math**

2 x^2 -2 = 0 2 (x^2-1) = 0 (x-1)(x+1) = 0 x = 1 or x = -1

**liberal arts math**

(4x+1)^2 = 4x(4x+1) + 1(4x+1) =16 x^2 + 4x + 4 x + 1 = 16 x^2 + 8 x +1 or do FOIL if you know it. so: - x^2 + 3 = 16 x^2 + 8 x + 1 17 x^2 + 8 x - 2 = 0

**maths**

L w = 414 L = w+1 so w (w+1) = 414 w^2 + w = 414 w^2 + w - 414 = 0 w = [ -1 +/- sqrt(1+1656) ]/2 w = [ -1 +/- 40.706 ]/2 w = 19.9

**physic**

.5 = .9*n log .5 = n log .9 n = log .5 / log .9

**Physics**

Pe at top = m g h = 3.3 * 9.81 * 1.03 a) Pe at 1.03-.27 = 3.3 * 9.81 * 0.76 find difference that difference is Ke in Joules so difference = (1/2) m v^2

**Physics**

falls 3 meters (1/2) m v^2 = m g (3) v^2 = 2 mg(3) v = sqrt (2 m g(3) You should remember forever This: when something falls distance h from zero speed at top and no air drag v = sqrt (2 g h) mass does not matter for this

**Physics**

Ac = v^2/r = omega^2 r v = omega * r omega = 33.3 * 2 pi / 60 = 3.49 radians/second Ac = 3.49^2 (.15) = 1.82 m/s^2 2. F = m a = .0073 * 1.82 = .0133 Newtons

**algebra**

use 4 for x f(4) = 4 * 4 + 7 = 16 + 7

**Physics 141**

speed of rock = 15.5 , mass = .32 speed of wagon = v , mass = 92.7 initial momentum = 93 * .52 = 48.4 final momentum = initial momentum so 48.4 = .32*15.5 + 92.7*v solve for v if backward 48.4 = -.32*15.5 + 92.7*v

**Calculus Check my answer**

integral (x^2/2 + x + 5)dx x^3 /6 + x^2/2 + 5 x at 4 minus at -4 64/6 + 8 + 20 - ( -64/6 + 8 -20 ) 64/3 + 20 + 40 64/3 + 180/3 = 244/3 = 81 1/3

**Chemistry**

HCl + NaOH --- > H2O + NaCl balanced as is One mole of NaOH for every one mole of HCl because the equation balances with one of each .68 * .29 = .1972 moles of HCl so we need .1972 moles of NaOH

**algebra**

y = k x -252 = k (84) k = -252/84 = -3 y = -3 (74) y = - 222

**science(check answers)**

2. I think B

**Physics 141**

south momentum = 75 * 7.35 = 551 east momentum = 45 * 2.85 = 128 new mass = 45 + 75 = 120 new momentum = old momentum (Newton #1 law) south speed = 551/120 = 4.59 east speed = 128/120 = 1.07 theta = tan^-1 (4.59/1.07) = 76.9 degrees Vf = sqrt(4.59^2+1.07^2) = 4.71 m/s

**Math**

12/4 = 3

**Math**

u - 10 = -12 add 10 to both sides u = +10 -12 u = -2

**Math**

2009 20,480/.98^4 2010 2011 2012 20,480/.98 2013 20,480 20,480/.98^4 = 22,204 domain is 2009 to 2013 as far as we know and the range is 20,480 to 22,204

**math**

A = 3 B C = 2.2 B C/A= 2.2/3 = .733 C is not more potent than A. It is 73.3 percent as potent as A

**Physics!**

2*2.4 /1 watts = 4.8 watts

**math**

8/10 = .8 = likely

**Physics**

the same as the work done lifting it m g h = 600 * 1.6 Joules

**Physics**

600 * 9.81 * 1.6 Joules

**math**

4/56 is unlikely

**Finance**

.11*68 = 7.48 7.48 - 3.85 = 3.63 expected increase in price 3.63 = x (68) x = .0533 or 5.3%

**physics**

Fx = 35 cos 25 friction work = -35 cos 25 (20) gravity does none, not in the direction of motion same as friction work but positive sign Fx = friction work /20 and F = Fx/cos 25 total work is friction work since no vertical motion

**math**

A cube only has 6 sides but anyway on your octahedron 2,4,6,8 are even 1,3,5,7 are odd so probability of even is .5, probability of odd is .5 in other words, likely as not

**math**

C = 2 pi R

**Math**

Yes

**physics**

weight = 1550 * 9.81 so force up = 1550*9.81 + 125 work = force up * 40 meters

**Algebra 1 (Step-by-Step)**

first I have to take a -1 out so it is easier -1(4 x^2 + 8 x - 5) one way to get 8 is with 2 and 10 -1 (2 x + 5)(2 x - 1)

**Geometry**

Huh? in a rectangle the diagonals are equal. 18 x - 28 = x + 380 17 x = 352 x = 20.7 etc

**Calculus**

I think you did it correctly. Of course the domain is limited because the answer is imaginary if x <3

**English**

4. added Well, it is vocabulary :)

**math**

It is difficult to make a seven apple pie with six apples, but so be it, go ahead, make the pie with less apple.

**Physics**

F = -kx = m a assume simple harmonic motion y = A sin (2 pi f t) then a = acceleration = - (2 pi f)^2 y ans -k y = - m (2 pi f)^2 y or 2 pi f = sqrt (k/m) period = 1/f = (1/2pi) sqrt(m/k) double m 2 pi f' = sqrt(k/2m) = old f/sqrt 2 3. well same deal but times sqrt 2 now

**Physics**

100 = k x 120 = k (x+.04) = k x + .04 k -----------------------------subtract -20 = kx - kx - .04 k 4 k = 2000 k = 500 N/m

**Algebra**

No (v^2 -9) = (v+3)(v-3) BUT (v+3)(v+3) = v^2 + 6 v + 9

**science**

loss of nutrients, must add fertilizer or rotate crops preferably with something like beans that fixes nitrogen from the air into the soil for decomposition if you have to pick one pick b

**science**

meanders are formed by the flow scouring one side of the stream and depositing on the other so I would say it is evidence of eroriding and depositing glacial till is junk deposited by glaciers 3 = a) but you knew that

**Physics**

because it has a battery which is charged by sunlight.

**Physics**

If the resistors are all in SERIES then the total resistance is the sum: 7 + 9 + 2 = 18 ohms i = V/R = 9/18 = 0.5 amperes

**physics**

almost 8 m/s (in my head)

**physics**

dropped 3 meters if no friction (1/2) m v^2 = m g h v = sqrt (2 g h)

**Physics**

weight = m g = 5.19 (9.81) normal force = 5.19(9.81) - 3.23 sin 20 pull force = 3.23 cos 20 work done per second = power = 3.23 cos 20 (3.38) Watts. Without time can not get energy. power wasted to heat = all of it above 3.23 cos 20 = mu (normal force above)

**Physics**

distance block moves down = ho + .198 loss of potential energy by block = .540 ( 9.81 ) (ho+.198) gain of potential energy by spring = (1/2)(320)(.198). This is energy gained by spring and lost by block. so .540(9.81)(ho+.198) = (1/2)(320)(.198) solve for ho then do it for 3 ho

**science**

v = Vi + a t v = 2 + 5*4 = 22 m/s

**Math**

2 L + 2 w = 54 so w = 27 - L also w = L/2 so L/2 = 27 - L 3 L/2 = 27 L = 18

**math**

x+2 = -2x + 20 3 x = 18 x = 6 so side = 8 14 - 8 = 8 so 14-x works and 2x + 4 is not 8

**Physics**

mgh = 10 * 9.81 * 1 + 20 * 9.81 * (1/2)

**Physics**

typo = Fx(R1y-R2y)k + Fy (R2x-R1x)k By the way the vector product F X (R2-R1) is a moment called a "couple".

**Physics**

I will do it in two dimensions, similar in 3 moment = F1 X R1 + (-F1) X R2 = (R1y Fx - R1x Fy)k -(R2y Fx -R2x Fy)k = Fx(R1y-R2y)k +Fy (R2x-R1y)k so in k direction and depending only on how far apart the two forces are, not the origin of R1 and R2

**Mathematics**

18/2

**Please Help with Physics Problems???????**

Spring potential energy = (1/2) k x^2 total energy = (1/2) m v^2 + (1/2)k x^2 = 8.6 Joules Power = F v = k x v

**Physics please help?????**

2.9*-3.2 +5.7*4.6 = 16.4 W yes -1.7 * v = -6 v = 3.53 m/s

**physics**

h = Hi + Vi t - 4.9 t^2 0 = 8 + 3 t - 4.9 t^2 t = [ -3 +/- sqrt (9+157) ]/-6 t = [ - 3 + / - 12.9 ] / -6 = -.5 +/- 2.15 = 1.65 seconds

**Maths**

12 + n = .5(42+n) 12 + n = 21 + .5 n .5 n = 9 n = 18

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