# Posts by Damon

Total # Posts: 30,560

**Math typo **

area is proportional to length dimension squared for similar objects D^2/d^2 = A/a Howevr what you typed makes no sense. 1. diameter of basketball is not in square inches If the diameter is 9.5 inches, the area is not 1810 area = 4 pi r^2 =4*3.14*4.75^2 =283 in^2 by the way ...

**Chinese**

This might help: https://www.mdbg.net/chinese/dictionary?page=worddict&wdqb=zhe&wdrst=0

**Algebra**

2(1+pi^3) ? about 64

**Algebra 2**

when is it zero (cross x axis?) z (z^2 +7 z +10) = 0 z (z+2)(z+5) =0 so at z = 0 , z = -2 , z=-5 if z<-5 try z = -6 -6(-4)(-1) is -24 so NO then between -5 and -2 try -3 -3(-1)(2) = +6 so YES between -1 and 0 try -.5 -.5(1.5)(4.5) = - so NO bigger than 0, try +1 1(3)(6) = ...

**Math**

Hmmm Writeteacher practicing presidential tweets :)

**Physics**

m g = 5*10 = 50 Newtons (on earth)

**Physics**

moved down 1.8 not 5.3 meters

**History**

mean, they were wicked mean.

**Math**

F = k x 15 = k *10 k = 1.5 check: 24 = 1.5 x x = 16 sureenough so 1.5 oz/inch = 1/1.5 inches/oz = 2/3 = 0.6666.... in/oz

**Math**

o + y = 21 o = 7 + 6 y so 7 + 7y = 21 y = 2

**Math**

.075*original = 0.39 so original = 5.2 (must be an old text book) new = 5.2*1.075 = 5.2+.39 I hope :)

**Algebra 1**

24 = 1.20 x

**Physics**

100 cm = 1 meter g = -9.81 m/s^2 (1/2) m v^2 = m g h v = sqrt (2 g h) v = sqrt (2*9.81*1)

**Physics**

t1 = 5/11.3 = .4425 hour t2 = 5/14.9 = .3356 hour waiting time = difference= .1069 hr = 6.415 minutes = 6 minutes and 25 seeconds

**science**

agree (but Googled :) https://www.google.com/search?q=size+of+milky+way+galaxy+in+light+years&ie=utf-8&oe=utf-8

**Physics**

phase 1 a = 58.8 and t = 5 Hi = (1/2) a t^2 = 29.4*25 = 735 meters Vi = a t = 58.8 * 5 = 294 m/s Phase 2 a = -9.81 m/s^2 v = Vi - a t v = 294 - 9.81 t v = 0 at top t = 30 seconds more h = 735 + 294(30) -4.9 (30^2) = 735 + 8811 - 4410 = 5136 meters

**math**

sum of distances from point on ellipse to foci = 2a where a is long semisaxis = 3 so 2 a = 6 = string length b = 2 (short semiaxis) center to focus =sqrt(3^2-2^2) = sqrt(5) = 2.236067977 feet which is tough with a ruler :)

**math**

4 a y = x^2 4 a (8) = (36/2)^2 32 a = 18^2 a = 10.125 in vertex to focus = a = 10.125 inches

**whoops**

Sorry about that, it said net !

**Chemistry**

well KBr is likely to be aqueous and ionized, if it is not then you have KBr solid and not the ions on the right. H+ + Br- + K+ + OH- --> K+ + Br- + H2O

**Physics**

Ah, so there is a question :) a = 3.6/.11 m/s^2 d = (1/2) a t^2 or to make it really easy average speed = 3.6/2 = 1.8 m/s distance = 1.8 m/s * .11 s

**Physics**

a = (3.6 -0)/.11

**math**

slope = 1/5 y intercept = 1 y = (1/5) x + 1 or 5y = x + 5

**physics**

F = - .69 m g = m a so a = -.69 g v=Vi + a t v = 18.0 - .69 g t v = 18 - .69(9.81)(1.29)

**Chemistry**

You are welcome :)

**Chemistry**

same number of mols of NaCL so half as many per liter 0.250 M

**Physics**

(a) no acceleration so +280 N (b)max friction force = 62*9.8*0.70 so -425 N

**Algebra2**

yikes c. if D = r t then t = D/r (you KNOW that :) 30 yards/6.47 yards/sec = 4.64 sec You KNOW it would not take him 194 seconds !!!! d. Julio runs at 9.11/2 = 4.555 yards/second 40 yards/ 4.555 yards/sec =8.78 seconds Which you already know is TWICE as long because half the ...

**math**

1 - ( [1-cos^2]/[1+cos] ) = ? cos 1 - (1-cos)(1+cos)/(1+cos) = ? cos 1 - (1-cos) = ? cos yes cos = cos :)

**Physics**

g = 9.81 = v^2/R at bottom m(9.81 + 4v^2/R) using v from part A

**science - Yes correct**

Yes, correct

**PreCalculus**

The right hand side says sin x You must make the left hand side come out sin x That is what I did Yes, I also used sin^2 + cos^2 = 1 in saying 1 - cos^2 = sin^2

**Math help**

first divide I get x^2 + 7 x +(7+k) with R = 3+k second divide I get x^2 + 4 x + (k-8) with R = -2k+12 so k+3 = -2k+12 3 k = 9 k = 3

**Calculus 1**

at some time between 2:00 and 2:10 if it is continuous and differentiable the acceleration must hit the average acceleration. (25 -20) mph/(10/60 hour) or in more usual units (36.67 - 29.33) ft/sec/600 seconds

**science**

x = 2 t + (1/2)(2) t^2 and x = (1/2)(6) t^2 so 3 t^2 = 2 t + t^2 2 t^2 -2 t = 0 t (2 t - 2) = 0 t = 1 x = 3

**math**

yes one could say though if you are into arithmetic and geometric sequences 80 + 70/100 + 70/10,000 .... 80 + .70 + .70/100 +.70/100^2 + .70/100^3 .. = 80 + .70(1/.99) geometric sequence sum

**Algerba 2**

yes, when t = 0, h = -20+20 = 0 if you are graphing (t,h) yes when t = 0, h = 0 (0,0) h = 0 when t is 0 and 4 (0,0) and (4,0)

**science**

I can not make a drawing here. You have to draw the parallelograms with adjacent sides at the given angles to each other and the answers are the diagonals.

**maths**

s = b + 6 s+3 = 2 (b+3) = 2 b + 6 b+6 +3 = 2 b + 6 3 = b s = 9

**Math**

x = 10^(3y) log x = 3 y log 10 = 3 y y = (1/3) log x x = log2(4y) 2^x = 4 y y = (1/4)2^x

**math**

.95^n = .5 n log .95 = log .5

**physics**

.00625 *365 = 4.50625 v v= .506 m/s yes average speed during stop = .506/2 = .253 m/s time to stop = .15 / .253 = .593 second acceleration = change in speed/time = -.506 /.593 = -.854 m/s^2 F = m a = 4.50625 *-.854 = -3.85 Newtons Ke initial = .5 * .00625 * 365^2 = 416 J Ke ...

**physics**

to find the total you add, not subtract. first car = 15480 yes second car = -20160 so disagree p = 15480-20160 = - 4680 total mass = 1700 kg 1700 v = -4680 v = - 2.75 m/s (1/2)860(18^2)+(1/2)840(24^2)-(1/2)(1700)(2.75)^2

**physics**

first half of flight: u = 27.5 cos 41 = 20.75 m/s forever Vi = 27.5 sin 41 = 18 m/s initial speed up v = 18 - 9.81 t at top v = 0 9.81 t = 18 t = 1.84 seconds upward 2 t = 3.68 seconds in air 3.68 seconds* 20.75 m/s = 76.3 meters range h = 18 (1.84) -4.9(1.84)^2

**physics**

(1/2) m v^2 = m g h v = sqrt (2 g h) (not T) v = 17.1 (not 1.7 ) average speed during fall = 17.1/2 = 8.57 m/s time to fall = 15/8.57 = 1.75 seconds Kim - it is dropped, not going up

**I do not know biology.**

....and therefore can not help you and my answers might just confuse you. However the same rationale applies to physics and chemistry and please do not mislead students.

**Math**

d = 7 j d+5 = 4(j+5) 7j+5 = 4 j + 20 3 j = 15 etc

**Locus**

6 y = -8 x + 1 is original line slope = -8/6 = - 4/3 we want a parallel line, so same slope y = -4x/3 + b so what is b ? line perpendicular to these has slope = 3/4 find a point on original line for example (0,1/6) now perpendicular line through that point is 1/6 = (3/4)(0) + ...

**help meee**

200 = pi r^2 h cost= c = 2 pi r h (.03) + (2)pi r^2(.05) c = 2 pi (.03 rh +.05r^2) but h = 200/pi r^2 so c = 2 pi (.03 r)(200/pir^2) + 2 pi(.05 r^2) c = 2 pi (6/pir + .05 r^2) c = 12/r + .1 pi r^2 dc/dr = 0 at min 0 = -12/r^2 + .2 pi r 12 = .2 pi r^3 r = 2.67 cm check my ...

**Physics**

190 N/78 kg ----->the 2.4 m/s^2 is correct. It is up if you feel heavier.

**physics**

13 is the distance, however displacement is a vector. x = 5 (east is right) y = -13 (south is down A = angle south of east tan A = 13/5 A = 69 degrees angle counterclockwise from x (east) = 360 - 69 = 291 magnitude = 13

**Algebra**

if top is .5625 and printed height = 7.75 then bottom + .5625 + 7.75 = 9 bottom = 9 - 7.75 - .5625

**algebra**

dx = -1 - 6 = -7 dy = 14 - 16 = -2 d = sqrt [(-7)^2 + (-2)^2 ] = sqrt(49 + 4) = sqrt(53) = 7.28 = 7.3 to nearest tenth

**Geometry**

https://www.jiskha.com/display.cgi?id=1507597009#1507597009.1507597209

**Geometry**

just did

**History**

yes

**math**

x = distance man from pole y = distance tip of shadow from pole (y-x)/6.2 = y/11 11(y-x) = 6.2 y 4.8 y = 11 x y = 2.29 x dy/dt = 2.29 dx/dt = 2.29 * 4.5 = 10.3ft/s

**History**

I think not c maybe google huguenot

**U,S, History (please help)**

I was calling you because of the stuff I am glad you deleted :)

**Ms Sue**

ah, hummm and yes it is Madison. Do you know why?

**one number error**

time = 5.55 * 2 pi /44.4 rad/s = .785 seconds to accelerate acceleration = alpha = change in omega/ change in time = 88.8/.785 = 113 rad/s^2 and of course 77.7 = I (113)

**Physicss**

torque = I alpha where alpha = d omega/dt = angular acceleration now velocity proportional to time so average angular velocity = 88.8/2 = 44.4 rad/s does 5.55 *2pi radians so time = 5.55 * 2 pi /44.4 rad/s = .0765 seconds to accelerate acceleration = alpha = change in omega/ ...

**Algebra**

You said to use substitution but there is no practical reason not to use elimination and I did so automatically for the second half of the problem, sorry.

**Algebra**

well, we both used elimination at one point or another, going back a bit we had -8x + z = -25 and we know +2x +2z = 4 so use z = 8x -25 to substitute in the last one 2x +2(8x-25) = 4 18 x -50 = 4 18 x = 54 x = 3 again, whew !

**Algebra**

get rid of y so you can use the third eqn y = 8-x-z so -4x + 4(8-x-z) + 5z = 7 -8 x + z + 32 = 7 -8x + z = -25 and we know +2x +2z = 4 -16x +2z =-50 + 2x +2z = 4 --------------- -18 x = -54 x = 3 now go back

**Math**

Well, I suppose 10 * 12 = 120

**Physics**

You are welcome.

**Physics**

first the shooter: horizontal velocity = us = 7.8 m/s forever vertical velocity = vs = - g t =-9.81 t at .42 s this is - 9.81*.42 = -4.12 m/s now the water horizontal velocity = u= 7.8 + 11*.707 = 15.6 m/s forever vertical velocity =vw = -4.12 + 11*.707 = 3.66 AT .42 s use u...

**Physics your turn**

Hey I just did the two satellites. You do this the same way.

**Physics**

initial momentum = 5.5*10^3*0 +7.5*10^3*.2 =1.5*10^3 final is the same (5.5+7.5)*10^3 v = 1.5*10^3 v = .115 m/s initial ke = (1/2)(7.5*10^3) .2^2 = .15*10^3 = 150 Joules final ke = (1/2)(13*10^3) .115^2 = .0865*10^3 = 86.5 Joules now do it the other way around with first sat ...

**Physics! Please help!!**

320+725 = 1045 g = 1.045 kg friction force = 1.045*9.81 * .4 F - friction force = 1.045 * 2.25 m/s^2

**Physics**

weight of brick = m g = 23 * 9.81=226 N friction resistance maximum = 226*.17= 38.4 N on brick: T - 38.4 = 23 a so a= (T-38.4)/23 on weight 19*9.81 - T = 19 a so a = (186-T)/19 23(186-T) = 19(T-38.4) solve for T, the tension in the thread.

**Physics**

I guess potential energy is zero when entire rope lies on table :) ************************************** Since no Joules are lost in this problem, the total mechanical energy remains ZERO ************************************* That is the end but if you really want to make a ...

**You try first**

What are you stuck on? I would rewrite the first one as 1 z^2 + b z + c = 0 z = [-b +/- sqrt(b^2-4c)]/2 [z+{b -sqrt(b^2-4c)}][z+{b +sqrt(b^2-4c)}]=0 so -b/2=2 so b = -4 .5 sqrt(16-4c) = 3i sqrt (16-4c) = 6i 16-4c = -36 4c = 52 c = 13 z^2 -4z + 13

**Finite Math**

99 marbles first green = 55/99 second green = 54/98 so (55/99)(54/98) etc for b first green, second red plus first red, second green

**Math**

A 9000 panels , 900 defective B x panels, .03 x defective panels = 9000 + x defective panels = 900 + .03 x .06 = (900+.03x)/(9000+x)

**Algebra 2**

same deal, (x-5)^2 or (x+5)^2 a = 10 or -10 (9)(x^2+16/9 x + c/9) 9(x+8/9)(x+8/9) (3x+8/3)(3x+8/3) 64/9

**Algebra 2**

(x+/-b)(x+/-b) 2 b = 16 b = 8 (x+8)(x+8)=x^2+16 x + 64

**MaTh**

i-1-i+1+i-1 ......

**physics**

average speed = 10/2 = 5 distance = 50 so stop time = 50/5 = 10 seconds a = change in speed/change in time =-10/10 = -1 m/s^2 so F = m a mu m g = m a mu = 1/9.81

**physics**

S 5.5 - 2.8 = 2.7 km W 2.9 km magnitude = sqrt(2.7^2+2.9^2) angle A s of w tan A = 2.7/2.9 angle desired = 180 + A

**math**

-5*3.15 tricky is percent per day (compound)

**Physics!**

weight component down = m g cos 34 friction force up = m g cos 34 * mu so mu m g cos 34 + 240 = m g sin 34

**physics!**

I will assume ox 1 is uphill so it drags back on box 2 and they accelerate together Forces down slope (7.6 +1.6) g sin 31 = 4.74 g Forces up slope (7.6*.2 +1.6*.1) g cos 31 = 1.44 g total mass = 7.6+1.6 = 9.2 kg so (4.74-1.44)g = 9.2 a a = .359 g if g = 9.81 m/s^2 a = 3.52 m/s^2

**Physics!**

total mass = 14 kg total force down = 7 g - .15 *7 g cos 28 a = total force/14

**stats**

000 to 999 0 through 9 0 through 9 0 through 9 10^3 = 1000 so 1/1000 I do not know what #3 means either

**MATH**

Enough already, look up properties. Need to know them.

**MATH**

Hey, distributive property again! or just common sense 12 + 32 = 44 OR 4*11 = 44

**Mathematics**

SKETCH IT ! last corner at x = -1, y = -6 top goes from -1 to +6 (how long?) side goes from -6 to +2 (how long?)

**MATH**

http://www.google.com/search?q=distributive+property+of+multiplication&ie=utf-8&oe=utf-8

**Mathematics**

distributive property 5*x + 5*3 both numbers even so for starters 2 (3x-5y) 3 and 5 are prime numbers, can not be factored. The end.

**math**

s+r = 51 so r = 51-s s-6 = 2(r-6) substitute s-6 = 2 (51 - s - 6) = 2(45-s) =90-2s 3 s = 96

**Science**

liquid ---> gas molecules ---> split up and reform into new molecules

**Science yikes!**

1. Only the NEUTRON has no charge 2. electrons in nucleus? I think not 3. disagree, not moving, no Ke = (1/2) m v^2 4. What does the word "conservation" mean to you. You better go back and read the chapter. !!!!!

**Physics**

(1/2) m v^2 = m g h if h = v (1/2)h^2 = g h h = 2g

**Physics**

v = Vi - g t h = Vi t - .5 g t^2 at height h, v = Vi/2 Vi/2 = Vi - g t g t = Vi/2 t = Vi/(2 g) at height h h = Vi^2/(2g) - .5g (Vi^2/4g^2) h = (1/2)Vi^2/g - (1/8)Vi^2/g h = (3/8) Vi^2/g at max height H, v = 0 0 = Vi - g T where T is time at max h T = Vi/g H = Vi T -.5 g T^2 H...

**physics**

As far as I know lignum vitae is still used for many stern tube bearings, although probably no longer by the Navy.

**sinks, denser than fresh (or most salt)water**

None, sinks That density is greater than fresh water, typo? mass = 1.05 *200 = 210 gm so Archimedes says mass of water displaced = 210 gm but water(fresh, out of my geography) is 1.00 gm/cm^2 so 210 g = 1.00 * V of water V of water = 210 cm^3 of water displaced, we need a hunk...

**Physics Thrust**

I did it for on earth. Bobpursley did it for in space with no gravity.