Thursday

October 2, 2014

October 2, 2014

Total # Posts: 18,776

**Physics**

yes, 0 = 42 + 75 a a = - .56 d = Vi t + .5 a t^2 d = 42(75) - .28(75)^2 = 3150 - 1575 = 1575
*August 8, 2014*

**History**

I do not see a problem in using the same things as answers an earlier question. You have me pretty confused though about what you think are advantages and disadvantages of ethnic neighborhoods. What do you think are advantages and what do you think are drawbacks?
*August 7, 2014*

**History**

cultural diversity and learning new cultures would not particularly be an advantage of an ethnic neighborhood. A family that moved into a mixed neighborhood would probably learn the new language and traditions faster. I would say advantages include mutual support both in ...
*August 7, 2014*

**what is the question ?**

You want zeros of y or what? if zeros: 4 x^2 - 12 x + 9 = 0 (2 x-3)(2x-3) = 0 x = 1.5, 1.5 double root If vertex etc: 4 x^2 -12 x = y - 9 x^2 - 3 y = (1/4)(y-9) x^2 - 3 y + 9/4 = (1/4)y (x-1.5)^2 = y/4 vertex at (1.5 , 0) which we knew already
*August 7, 2014*

**physics**

Well, there is a hard way and an easy way. Easy way height = h angle = A with no friction KE gained in slide = m g h (1/2) m v^2 = m g h v = sqrt (2 g h) average speed = v/2 = .5 sqrt (2 g h) time = average speed * h/sin A t = .5 h sqrt (2 g h) /sin A now with work done ...
*August 7, 2014*

**math**

12.5= 3/k multiply both sides by k 12.5 k = 3 divide both sides by 12.5 k = 3 / 12.5
*August 7, 2014*

**physics whoops**

Whoops, sorry, Steve is right.
*August 7, 2014*

**physics**

since the total displacement vector is zero the average speed is zero. let i be unit vector from point A to point B velocity outbound = 40 i velocity back = -60 i (40 - 60)/2 = -10
*August 7, 2014*

**Math**

5*4
*August 7, 2014*

**Math**

I did one of these for you. They are fundamentally all the same. The circumference of a circle is 2 pi r The area of a circle is pi r^2 Hey, draw a picture.
*August 7, 2014*

**Math**

6 w = 18 w = 3 so r = 3 A = pi r^2 = 9 pi
*August 7, 2014*

**math**

16 * 8 * 8
*August 6, 2014*

**math corrections**

I do not understand number 2. Typo? 4) .75/2 -.625/2 = .0625 (radius not diameter is used) 14) I get 40 (long, will elaborate later) 24) (30/250)(30) = 3.6
*August 6, 2014*

**Algebra**

2.68*10^-5 watts/cm^2 to dB You want Watts/m^2 so multiply by 10^4 2.68 * 10^-1 Watts/m^2 definition of dB for sound: dB = 10 log (watts/m^2 intensity /10^-12) = 10 log (2.68*10^11) =10 [ log 2.68 + 11 ] = 10 [ 11.428 ] = 114 dB LOUD !!!!
*August 6, 2014*

**Physics**

displacement vector / time
*August 6, 2014*

**physics**

Force = change in momentum / change in time if force the same and time the same then change in momentum the same (answer to first question) f = m v /t f = 2 m V /t so V = v/2 Ke of little mass = (1/2) m v^2 Ke of big mass = (1/2) 2m v^2/4 =(1/2)m v^2/2 so Ke of big mass = 1/2 ...
*August 6, 2014*

**PHYSICS**

increase of potential energy of block = m g h = (2.515)(9.81)(.15) = 3.70 Joules so (1/2) m v^2 = 3.7 Joules at bottom (1/2)(2.515)v^2 = 3.7 v = 1.72 m/s at bottom after collision momentum after collision = 2.515 * 1.72 = 4.31 g m/s momentum before collision = .015 v so v = 4....
*August 6, 2014*

**physics**

change those to meters / second (1/2) m (V2^2-V1^2) note 6^2 - 5^2 = 36-25 = 11 but 3^2 - 1^2 = 9 - 1 = 8
*August 6, 2014*

**physics**

v = sqrt (2 g h) = sqrt (2 * 9.81*12) a ) Ke = (1/2)(45) v^2 b ) stops in .32 m work = Force * .32 = Ke from part a
*August 6, 2014*

**physics**

momentum down = 1.2 *25 momentum up = 1.2 * 10 change of momentum = 1.2 (25 + 10) impulse is change of momentum Force = change in momentum/change in time = answer to part a / .2
*August 6, 2014*

**statistics**

I get .8186 between 24 and 48 so about 819 out of 1000
*August 6, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*August 6, 2014*

**SCIENCE**

http://www.jiskha.com/display.cgi?id=1407333641
*August 6, 2014*

**SCIENCE**

aaarrrgghhh 1.5 (9.81) h = 29.4 still
*August 6, 2014*

**PHYSICS**

work = increase in kinetic energy = (1/2)(18,000) (40^2 -30^2) in Joules force * distance = work in Joules distance = average speed * time d = 35 * 5 so Force = work from part a / d power = work/time = work from part a / 5 seconds in Joules/sec which is Watts
*August 6, 2014*

**PHYSICS**

You are welcome.
*August 6, 2014*

**PHYSICS**

http://www.jiskha.com/display.cgi?id=1407324138
*August 6, 2014*

**PHYSICS**

Hey, I just did this
*August 6, 2014*

**PHYSICS**

Newton #2 is Force = rate of change of momentum 6 = 3 (v-0) /10 solve for v final momentum = m v
*August 6, 2014*

**PHYSICS**

I guess it is hanging down on earth where g = 9.81 m/s^2 approximately F = m g = k x 2.5 * 9.81 = k (.42) solve for k b) F = k (0.50) c) U = (1/2) k x^2 = (1/2)(k)(0.35)^2
*August 6, 2014*

**SCIENCE**

m g h = 29.4 1.5 * 9.81 * h = 29.4 solve for h
*August 6, 2014*

**math**

Looks like magic to me.
*August 6, 2014*

**Physics**

no kinetic energy lost in collision Not only is momentum conserved but also sum of (1/2) m v^2
*August 6, 2014*

**Physics**

1) sqrt (20^2 + 30^2) 2) no horizontal force so no change in horizontal speed 3) slows to zero at top then comes back to original speed but downward 4) Like we said in #2, it is the same until it hits the charging warthog. 5) it is at max height, no speed up any more and no ...
*August 6, 2014*

**Physics**

.005 (300) = - 3 v v = -.5 Ke = (1/2)(.005)(300)^2 + (1/2)(3)(-.5)^2
*August 6, 2014*

**math**

Hey, look, you are not paying attention. it has highest power of 3 so three factors and three zeros however one of those zeros is repeated, x = -1 so zeros are -1, -1 , -1/2 and the three factors are (x+1) (x+1) (2x+1) now check by multiplying those three factors and see if ...
*August 6, 2014*

**math**

I gave you the whole thing factored (x+1)(2x+1)(x+1) zeros are -1 , -1/2, -1
*August 6, 2014*

**math**

try x = -1 for a zero 2(-1) + 5(1) + 4 (-1) + 1 -2 + 5 - 4 + 1 0 so (x+1) is a factor, now divide (x+1)(2x^2 + 3x + 1) (x+1)(2x+1)(x+1)
*August 6, 2014*

**physics**

He has a Uranium mine.
*August 6, 2014*

**physics**

mass irrelevant 78.4 = (1/2) g t^2 t^2 = 2 * 78.4 / 9.81
*August 6, 2014*

**Copy and paste does not work here**

We can see neither your equation nor the "following statements".
*August 6, 2014*

**math**

(1/5)(V+W+X+Y+Z)
*August 6, 2014*

**Math**

2(81) - 3(9) - 8(3) + 4 = 115
*August 5, 2014*

**math**

3 - 4 - 2 - 8/15 -45/15 -8/15 -53/15
*August 5, 2014*

**physics**

The horizontal component of velocity DOES NOT CHANGE There is no horizontal force. Therefore there is no horizontal acceleration.
*August 5, 2014*

**Finance Help**

In the end, looking far ahead, the value of a share of a company is the present value of a future stream of dividends. Of course people do not think much about that for most stocks, particularly those that presently pay no dividends, because there are so many other factors ...
*August 5, 2014*

**Math**

Nope, C 1.5 inches
*August 5, 2014*

**Math**

L = 10 - 2x w = 8 - 2 x v = L * w * x v = (10-2x)(8-2x)x v = (80 - 36 x + 4 x^2)x v = 4 x^3 - 36 x^2 + 80 x do you do calculus? if so the min or max when dv/dx = 0 0 = 12 x^2 -72 x + 80 0 = 3 x^2 - 18 x + 20 x = 3 +/- (1/3)sqrt 21 = 3 +/- 1.52 the plus sign is too big a width ...
*August 5, 2014*

**History**

You are welcome ;)
*August 5, 2014*

**History**

How much does this machinery cost? Assuming money was borrowed from the bank to buy it all, how do the loan payments compare with the monthly payments to the bank for the farm land and the house and barn? Does the cost of this equipment force you to buy a much bigger farm than...
*August 5, 2014*

**Algebra**

149.25 = x - 0.25 x 149.25 = 0.75 x x = 149.25 / 0.75
*August 5, 2014*

**math hw**

20/60 = 1/3 of an hour distance = speed * time 160 miles = speed * (1/3) hour speed = 3 * 160 miles/hour = 480 miles/hour
*August 5, 2014*

**Pre Cal**

100 at 50 degrees counterclockwise from x 50 at 160 counterclockwise from x x component = 100 cos 50 + 50 cos 160 = 64.28 - 46.98 = 17.30 y component =100 sin 50 + 50 sin 160 = 76.60 + 17.10 = 93.70 magnitude = sqrt (17.30^2 + 93.70^2) angle = tan^-1 (93.70/17.30)
*August 5, 2014*

**Math**

You are welcome. Good luck !
*August 5, 2014*

**Math**

Here: http://www.purplemath.com/modules/mtrxmult.htm
*August 5, 2014*

**Math**

|24 -12| |0 +3 | |-18 -9|
*August 5, 2014*

**Math**

Well, if you multiply a matrix by a scalar, you multiply every element by the scalar
*August 5, 2014*

**Math**

Perhaps nothing. I need to figure out what the question is :)
*August 5, 2014*

**Math**

Oh like this? | -8 +4 | -3| +0 +3 | | +6 +3 | now does it want the product or -3 times the determinant I wonder ?
*August 5, 2014*

**Math**

Anyway --- go here : http://matrixcalc.org/en/
*August 5, 2014*

**Math**

can you describe it in words? is it a single matrix like | -8 +4 | | +0 +3 | | +6 +3 | and you want something about it ?
*August 5, 2014*

**Math ?????**

I have no idea what you are doing. Are those vectors or matrices or what ?
*August 5, 2014*

**Alegbra**

T >/= -6
*August 5, 2014*

**Alegbra - Ms Sue**

Ms Sue, negative divide changes arrow direction.
*August 5, 2014*

**Alegbra**

5 > 4 - 2 y 1 > -2 y divide by -2, when you multiply or divide by a negative, change direction of arrow - 1/2 < y so y > -1/2 now check that by picking some y which is greater than (to the right of on number line) -1/2 like maybe -1/4 8 - 3 > 4 - 2(-1/4) ???? 5...
*August 5, 2014*

**physics**

call north y and east x phase one: vx1 = 40.6 cos 25 vy1 = 40.6 sin 25 x1 = 40.6 cos 25 * 3 y1 = 40.6 sin 25 * 3 Phase 2 vx2 = 0 vy2 = 23 x2 = x1 + 0 * 7.4 y2 = y1 + 23 * 7.4 d = sqrt (x2^2 + y2^2)
*August 5, 2014*

**Physics**

50 meters plus whatever, find whatever v = Vi - 0.981 t v = 0 at max height so t = 30 m/s / 9.81 m/s^2 t = 3.06 seconds upward h = 50 + Vi t - 4.9 t^2 h = 50 + 30 (3.06) - 4.9 (3.06)^2
*August 5, 2014*

**Calculus-Math**

A = 2 (t+1)(t^.5) dA/dt = 2 [ (t+1)(.5 t^-.5) + t^.5 (1) ] = 2 [ .5 t^.5 +.5 t^-.5 + t^.5 ] = 2 [ 1.5 t^.5 + .5 t^-.5 ] = 3 sqrt t + 1/sqrt t = (3 t + 1 )/sqrt t
*August 5, 2014*

**Math**

10/12 + 9/12 = 19/12
*August 5, 2014*

**Geometry**

I am not sure how to do a two column proof of this. If the word "image" or "model" implies similarity, then it is just a one line proof; if it is a valid image, then the model and the bicycle are similar. (angles are the same and lengths are proportional.)
*August 5, 2014*

**Geometry**

If corresponding angles are the same and if all corresponding lengths are in the same ratio then the images are similar.
*August 5, 2014*

**Geometry**

The image is similar (in the geometrical sense) to the original. Therefore if any length on one image is 9 times its length on the other image, then all lengths are in that ratio. Use any length, for example the diameter of the front wheel on each image :)
*August 5, 2014*

**Economics**

Nope
*August 5, 2014*

**economics**

1. costs money, employs bureaucrats 2. keeps people alive, employs bureaucrats
*August 5, 2014*

**Afrikaaans**

Ik ken een beetje Nederlands en ik versta je wel, maar wat heb je nodig? Wij kunnen een essay over je school niet schrijven. Ik weet niets over je school.
*August 5, 2014*

**geometry**

did you leave out the 3 120s that go with the three 50 s ?
*August 5, 2014*

**geometry**

the exterior angles have to sum to 360, all the way around with exterior of 50 we have exterior of 150 so far and 360 - 150 = 210 left for exterior angles exterior with 127 interior = 53 exterior with 135 = 45 so 210 - 53 - 45 = 112 left for exteriors exterior with 173 = 180-...
*August 5, 2014*

**typo ?**

4000 meters / second maybe? Newton #2: Force = change in momentum / time (F= m a if m is constant but here it is not) change in momentum/second = [.050 kg * (4000 - 0) m/s]/second = 200 Newtons
*August 5, 2014*

**History**

The farmers got caught in a cycle of debt because it says they did not have capital to buy land and therefore I suspect they had to borrow.
*August 5, 2014*

**physical**

LOL !!! This is a trick question. You know the answer. It is exactly the same as throwing a ball straight up. It takes just as long to go up (0 = Vi - g t) so t = Vi/g h = Vi t - (1/2) g t^2 as it takes to go down 0 = h - (1/2) g t^2 = Vi t - (1/2) g t^2 - (1/2) g t^2 t = Vi...
*August 5, 2014*

**English/ Help**

Now what about A? Who misunderstood what? Did they think he was Darth Vader when he was actually Luke S? Now what about B? Was there milling around and people stepping on others' toes trying to get selfies and autographs? Now what about C? Who left. I might have but I was ...
*August 5, 2014*

**English/ Help**

http://www.jiskha.com/display.cgi?id=1407196486
*August 5, 2014*

**English/ Help**

Could swear I have seen this question before.
*August 5, 2014*

**college physics**

omega = initial omega + alpha * t if alpha is constant and it starts from rest t = omega/alpha
*August 5, 2014*

**math**

C = 9000 + 21 x yes Revenue = R = 49 x P = 49 x - 21 x - 9000 so P = 28 x - 9000 now for some reason they did not asdk how ma tires must be sold to break even but it would be P = 0 28 x = 9000 x = 9000/28
*August 4, 2014*

**Algebra**

Your notation is extremely awkward. We normally write x to a power as x^power like x^3 is x cubed Now I will do it your way but you have errors starting with the sign in the first line x(2x squared-x-3)+ 1(2x squared-x-3) should be x(2x squared-x-3) - 1(2x squared-x-3) then x*...
*August 4, 2014*

**Algebra**

again: http://www.jiskha.com/display.cgi?id=1407198511
*August 4, 2014*

**Algebra**

Did I not just do that ?
*August 4, 2014*

**English/ Help**

hmmmm ..... each pointed to their records of service and academic excellence.
*August 4, 2014*

**Pre-College Algebra**

distributive property: x * (2x^2 - x- 3) -1* (2x^2 - x- 3) = 2 x^3 - x^2 - 3 x - 2 x^2 + x + 3 combine like terms = 2 x^3 - 3 x^2 - 2 x + 3
*August 4, 2014*

**math test review**

h^2 + 64(2) = 18^2 = 324 h^2 = 196 h = 14 area = (1/2)(8sqrt 2)(14) =56 sqrt 2
*August 4, 2014*

**Physics**

You are welcome.
*August 4, 2014*

**Physics**

Stand on a scale and push on the ceiling :) Third law. Force by man up on bars --> force down on man Sum forces on the man who is not accelerating up or down m g down + handlebar force down force up on man = pedal force net force = 0 so no change of momentum (F = m a = 0) ...
*August 4, 2014*

**English/ Help**

I agree with you but I was a physics major :) C and D are just plain wrong. The car, not the fuel efficiency, is designed :)
*August 4, 2014*

**math hw**

all multiples of 6 are even and multiples of 3 Venn diagram (intersection is mult of 6) n are multiples of 6 22 - n are even only 15 - n are 3 only (22- n) + n + (15-n) = 30 37 - n = 30 n = 7
*August 4, 2014*

**math hw**

Hey (a^2-b^2)= (a+b)(a-b) remember forever (a+b)(a-b) = 20 2(a-b) = 20 a - b = 10
*August 4, 2014*

**math**

g = 2 b - 5 so yes, but they said b for boys
*August 4, 2014*

**physics**

You also need specific heat of iron and melting point Watch your units, grams or kg , Joules or calories to get up to Tmelt heat = 1000 g * specific heat iron in Joules/gram deg C *(Tm-20) to melt heat = 1000g * 33 J/g
*August 4, 2014*

**Calculus**

y = x^.5 y' = .5 x^-.5 sketching this I am going to reverse slope equation y' at tangent = m = (y-yo) /( x-xo) = .5x^-.5 y' = m = (y-0)/(x+16) = .5 x^-.5 x^.5 /(x+16) = .5 x^-.5 x/(x+16) = .5 x = .5 x + 8 .5 x = 8 x = 16 so the tangent hits the curve at x = 16 ...
*August 4, 2014*

**physics**

do vertical problem find Vi, initial speed up Vi = 65.2 sin 34.5 find t where v = 0, top of curve v = Vi - 9.81 t 0 = Vi - 9.81 t solve for t, time at top, half the time in the air max height h = 0 + Vi t - 4.9 t^2 now horizontal problem u = 65.2 * cos 34.5 the whole time ...
*August 4, 2014*

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