# Posts by Damon

Total # Posts: 30,065

**Calculus**

sqrt(36 + 64) = sqrt 100 = 10 so that vector is ten units long. If you divide each component by 10, you will get a vector of length one in that same direction so < -6/10 , -8/10 > or < -3/5 , -4/5 > by the way this is a 3,4,5 right triangle :)

**physics**

(a) m g h = 3 g (5) =15g at top BUT I assume you are choosing it to be ZERO at the bottom (b) (1/2)m v^2 = mgh = 15 g of course (c) v = sqrt (2 g h) v = sqrt(10 g) (c)

**Math**

4^2 /2 - 2^2 + 5 8 - 4 + 5 9

**Calculus**

As far as I know the first one is true, they differ by a constant. yes, true say f = x^2 g = x then F = (1/3) x^3 + C1 G = (1/2) x^2 + C2 integral f g dx = (1/3) x^4 + C forget the constants for now, no need F G = (1/6) x^5 like no way :)

**Calc**

dv/dt = a which is constant so v = c + at c is v when t = 0, v0 so v = v0 + a t dx/dt = v = v0 + a t so x = constant + v0 t + (1/2)at^2 constant is x when t = 0 or s0 x = s0 + v0 t + (1/2)at^2 (but we cheated and took physics so knew that)

**Geography**

g = b+40 b/g =3/7 so b =3g/7 so g = 3g/7 +40 7g/7 = 3g/7 + 40 4 g = 40*7 g = 70 b = 3*70/7 =30

**physics**

F = m a 5890 = (1070+2140) a a = 5890/(1070+2140) then Fjeep = 2140 a

**PLEASE CHECK OPERATIONS WITH FRACTIONS PART 2**

13. Kevin had 3/4 yard of string. He used 1/3 of the string for a school project. How many yards of string did he use for his project? A.5/12*** B.1/3 C.7/12 D.1/4 ============================== 1/3 * 3/4 = 1/4 I do not have time to go through all these but noticed this ...

**Math**

12 +14 = 26 26 * 10 = 260 260/2 = 130

**Bob**

I have answered this three times now.

**Science**

http://www.jiskha.com/display.cgi?id=1478031138

**Math**

1.25 * 12 = 15

**hellllllpppp**

23/63 as I said before 23 is a prime number. This fraction can not be simplified.

**Science**

http://www.jiskha.com/display.cgi?id=1478031138

**Maths**

2005 /4 = 501 1/4 2004/4 = 501 so -7 so 2

**Physics**

first 20 s slope of v = a = 2 m/s^2 v = 0 + 2 t x = (1/2)(2) t^2 at t = 20 v = 40 m/s x = 400 m from t = 20 to t = 50 v = 40 m/s a = 0 at t = 50 v = 40 new a = -40/25 x = 400 + 40(30) = 1600 from t = 50 to t = 75 v = 40 - 40/25(t-50) a = -40/25 x = 1600 +40(t-50) - 20/25(t-50...

**PHYSICS**

omega R = v omega = v/R = 12/1.5

**Maths**

yes

**Maths**

would it be 295,000 or 296,000 is 3 >/= 5 ?

**Maths**

(1.61 + 0.81 + 1.21) /3

**biology - genetics Mendelian**

need biology teacher

**Maths**

5.4 cm * 10 km/cm = 54 km

**Maths**

perimeter = 2*4 + 2*3.5 = 8 + 7 = 15 meters total area = 15 * 2 = 30 m^2 now subtract 2 and 1 = 3 so 27 m^2 27*3 = 81 dollars But not really if you ever did wall paper :) It never comes out like that perfectly, has to be lined up and edged perfectly so needs extra.

**Math**

-12 + n = -35 n = -35 + 12 n = - 23

**Maths**

sum = 180 = 2*90 two

**math**

2*8 = 16 16+5 = 21 so 21/8

**Maths**

10/10 - 7/10 = 3/10 2 Liters? that is 2,000 mL 3/10 (2,000) = 600 mL

**Maths**

1000/200 = 5 5 * 40 = 200

**Math**

7/8 - 3/4 is 7/8 - 6/8 = 1/8

**math**

what can you divide 23 by? Nada ! Prime the end 23/63

**math**

time starting at 2007 t n 0 35250 5 28200 7 ? n = m t + 35250 28200 = m (5) + 35250 5 m = - 7050 m = -1410 so n = -1410 t + 35250 if t = 7 years n = -1410 (7) + 3520

**geography**

Rivers ! Harbors ! Paths through deserts and mountain ranges!

**science plz correct me**

A. I thought I told you, more MASS

**AP Statistics**

I do not know what you did in unit but find mean and median for women and for men for example median women 21 26 26 30 31 33 33 34 34 35 37 38 41 41 41 42 49 61 72 74 80 There are 21 10, median, 10 10 smaller than 37 and 10 bigger median is 37 now do it for men is it higher?

**science**

E = i R 21 = 3 R R = 7 Ohms

**Science 7**

No! Read carefully, more MASS

**Science 7**

G M1 M2 / d^2 bigger mass, same d ---> bigger force

**Calculus**

well, x^2 +y^2 = 49/4 put that back in 2 (49/4)^2 = 49 (x^2-y^2) 49/8 = x^2 - y^2 49/4 = x^2 + y^2 2 x^2 = 3*49/8 well that is two points x values :) you have 2 y values for each x so 4

**Calculus**

find where dy/dx = 0 4 (x^2 + y^2)(2x + 2 y dy/dx) = 49 (2 x - 2 y dy/dx) when dy/dx = 0 4(x^2+y^2)(2x) = 49(2x) x^2+y^2 = 49/4 = r^2 it is a circle center at (0,0) , r = 7/2

**Pre-algebra**

74 is an integer 74/1 Now if you had said 7.4 I would have said 74/10 so still rational

**Pre-algebra**

1/1 2/2 4/2 or 4/1 in fact since every integer is divisible by one every integer is a rational number. You have to get far out to get irrational, like sqrt( 2 ) or pi or e Remember that fractions are generally ratios of whole numbers so rational like 3/273 is rational

**Science 7**

I guess if the switch is closed the bulb is on. yes G M/r^2 but we are assuming comparable radii

**Math-Check my answer**

3 a - 4 </= 5 3 a </= 9 a </= 3 yes

**math plz help**

LOL - I suppose it could be 7.5 but it said the GREATEST common factor well if they were 30 oz, we would not get 15 so it looks like 15 is the biggest that will go into all three 15 --> one ball 30 --> two balls 60 --> four balls

**Algebra**

well, I would multiply both sides by 15 x 15 x (2/15) = 15 x (13/x or 2 x = 15 * 13 x = 7.5 * 13 x = 97. 5 indeed Now some may say just cross multiply well ok 2 x = 15 * 13 immediately. but I do not like the words "cross multiply" despite the fact that they are ...

**science**

No way I am going to just say a heat wave is hot. What answers would you give if we were not around?

**physics**

I wonder if the cabinet is accelerating down call it a ma = mg - T m(9.81-a) = 2390 T - .68 * 193 *9.81 = 193 a or 193 a = 2390 - 1287 a = 5.71 m/s^2 (dangerous) m (9.81-5.71) = 2390 m = 583 kg

**Chemistry help emergency? (theoretical mass/mol)**

You do not have enough of one or the other, limiting the amount of Cu resulting. Use the one you do not have enough of. Your mols of Al must be at least 2/3 the number of mols of CuCl....... If it is less use it. If it is more use the CuCl ... and you will have some Al left over

**Maths (really hard)**

what is length AB? sqrt(4+ 64) = sqrt 68 = 2 sqrt 17 so length AC = sqrt 17 what is slope AC? It is -1/slope AB slope AB = -2/8 = -1/4 so slope AC = 4 now point C (x,y) Oh, wow, problem over go right one from A go up 4 from there what is hypotenuse? LOL sqrt 17 !!!! so x = 1...

**Maths (done question a but cant do b)**

-2 + -3 = -5 -5/2 = -2.5 which is y of C 4 ) 6 = 10 10/5 = 5 which is x of C so C(5, -2.5) now AC dx = 5-4 = 1 dy = -2.5 - -3 = .5 d^2 = 1+.25 now CB dx = 6 -5 = 1 dy = -2 - -2.5 = .5 d^2 = 1 + .25 the same

**LOL - so what is C (?,?)**

Do I have to do part a too ?

**maths**

change in y = 6 - (-3) = 9 change in x = 7 -4 = 3 so d = sqrt (81 + 9) = sqrt (90) = 3 sqrt 10

**Math**

You are welcome.

**Math**

85% = 85/100 = 0.85

**Calculus**

You are welcome.

**Calculus**

Sometimes conventional obscurity is insufficient and extraordinary efforts must be made to confuse the student. One seemingly simple but surprisingly effective technique is to reverse the usual roles of x and y.

**Calculus**

yes it is. Perhaps you are misled by the x being the independent variable instead of y When y = 1 x = 1^3 = 9 (1)^2 + 5 = 1 - 9 + 5 = -3 sure enough now the problem dx/dx = 1 = 3 y^2 dy/dx - 18y dy/dx 1 = (3y^2-18y)dy/dx dy/dx = 1/ (3*1^2 -18*1) dy/dx = 1/(-15) = -1/15 amazing...

**Science**

well, probably there was air and water in it and the air expanded in the heat pushing the water out.

**Math**

4 * 7 * 25 = 100 * 7 = 700

**chemistry**

pentaamminesulfatocobalt (III) bromide http://seattlecentral.edu/faculty/dwick/CC%20name.pdf 1L is the one, NH3 and SO4 reversed

**Physics**

I am going to assume a flat and earth and the sun at infinity :) In that case the tip of the hawk's shadow is directly under the hawk and moves at the hawk's horizontal speed. u = 6.09 cos 78.6

**physics**

2 pi radians in 332 sec so omega = angular velocity = pi/166 Ac = omega^2 r = (pi/166)^2 * 2870

**Science**

Hey, come on, if you reverse the direction of the current you reverse the direction of the magnetic field produced !

**Physics**

8 north and 2 east so sqrt(64+4) tan angle north of east = 8/2 = 4 3 + 8 + 5 = 16

**Calculus**

C = 2 pi r so r = 35/pi so dC = 2 pi dr so dr = dC/ (2 pi) = .9/(2pi) a = pi r^2 da = 2 pi r dr da = 70 pi dr da/a = 70 pi dr/a multiply by 100 to get percent

**4th grade math**

1) right, like 18 does not work 2) n = 12 * x*y*z*.... so n = 2 * 6 * x*y*z*....

**Calculus**

let z = t^2-1 then dz = 2 t dt or dt =dz/(2 t) and we have integral of t z^(1/3) dt = t z^(1/3) dz/(2t) = (1/2) z^(1/3) dz Got it :)

**chemistry**

maybe this would help? http://www.coursehero.com/file/p6s4k6su/Bis-ethylenediamine-More-Nomenclature-Feen-2-NO-2-2-2-SO-4-Bisethylenediamine/

**Physics**

if t is RISE time and Vi is initial speed up v = Vi - 9.81 t at top v = 0 so Vi = 9.81 * 36.761/2 (because it spends half the time going up) Now I hope you know 45 degrees gives max range New Vi = Vi sin 45 U = Vi cos 45 with new Vi find time to top same way 9.81 t = Vi time ...

**Math**

two circles of radius 6 in, any bigger will not fit. circle area = 2 (pi 6^2) = 72 pi rectanglearea = 12 * 24 waste = 12 *24 - 72 pi

**Applied math**

5 - (-2) = 5 + 2 = 7

**Pre Algebra**

d = 2 a d = 34 34 = 2a 34/2 = a a = 17

**algebra 2**

210 = 4 (v+w) 210 = 6 (v-w) 105 = 2 v + 2 w 105 = 3 v - 3 w 315 = 6 v + 6 w 210 = 6 v - 6 w --------------------add 525 = 12 v etc

**Science**

V = i R if V increases and i is the same, R must have increased. right

**Science**

second one is right

**Science**

NO F = G M m /R^2 more mass is more gravitational force it remains in orbit because the centripetal force is also proportional to mass m v^2/R

**Physics 11 urgent Steve, bob, damon pls**

PS Perhaps you missed that word "frictionless" Do not think you are pushing that box along a hockey rink. That requires friction and cleats on your shoes if on ice. If no cleats, if the box goes one way you go the other :)

**Physics 11 urgent Steve, bob, damon pls**

Before the push, the momentum of the system was zero so since there is no EXTERNAL force on the student/box system, After the push the total momentum of the system is zero. Therefore If the student goes North then The box goes South if north is + .8 (30) + v (20) = 0 v = -.8(...

**Calc.**

perimeter = 2 x + 2 y cost = c = 14 x + 4 y = 15400 or 7 x + 2 y = 7700 y = -3.5 x + 3850 A = x y = x(-3.5 x + 3850) = -3.5 x^2 + 3850 x dA/dx = -7x +3850 zero when x = 3850/7 etc

**Calculus AB**

f(6) = f(7) + f'(7) * (6-7) f(6) = 34 + 4 (-1) f(6) = 30 not 42 so I disagree

**Calculus AB**

dC/dx = change of totsl cost per change of number og bikes if dx = 1 then dC/dx = cost of that one cost of 2 more is about 2 dC/dx when x = 40 bu you better also have C(40) :) LOL, total cost goes negative for large number of bikes, very good deal

**Calculus AB**

A = .5 b h but b = h A = .5 b^2 dA = .5 * 2 b db dA/dt = 2 b db/dt = 14 db/dt

**Calculus AB**

0 = 0 + Vi(4) - 4.9 (16)

**Calculus AB**

potential energy at 40 m = m g h = 9.8 m *40 potential energy at bottom = 0 kinetic energy at 40 m = (1/2)m *25 kinetic energy at bottom = (1/2) m v^2 so (1/2) v^2 = 9.8(40) + 12.5 v^2 = 9.8*80 + 25

**physics**

at top force to left from wall = Fxt vertical force from wall = 0 at bottom Force up from floor = Fzb max force to right from floor =Fxb = .4 Fzb Gravity force down at 10 meters from base = 750 N not accelerating so Fzb = 750 Fxb = .4(750) so Fxt also = .4(750) but to left ...

**Physics**

LOL - trick question energy is conserved if the ball is caught at the same height as it left the foot, the speed is the same. 19 m/s same horizontal component (of course) same vertical component but down not up (conservation of energy)

**university physics**

If it was at rest and there is no EXTERNAL force then: total x momentum = 0 total y momentum = 0

**US History**

State names usually have some historical significance, named after a native American chief or tribe (eg Massachusetts) or Historical Leader (Viginia for virgin queen Elizabeth or Pennsylvania for William Penn etc) or place where some settlers came from (New Whatever)

**Physics**

1 cm^2 = 10^-4 m^2 delta L = L F/(EA) .005 = 20 /(E*10^-4) E = 4*10^7 Pascals Think material is like rubber or you have a typo.

**Algebra**

worker 1 does job in x hours worker 2 does it in x+1 hours worker 1 is x hr/job or (1/x) jobs/hr worker 2 is x+1 hr/job or 1/(x+1) jobs/hr time for both together is two hr so [(1/x)jobs/hr + 1/(x+1) ]2hr = 1job 1/x + 1/(x+1) = .5 (x+1) + x = .5 x(x+1) 2x + 1 = .5 x^2 + .5 x .5...

**Calculus**

first do x components 3(-3) + 2(5) = -9 + 10 = 1 now y components 3(7) + 2(1) = 21 + 2 = 23 < 1, 23 >

**Math practice test**

The one on the lower left :)

**Math**

girls = g boys = 1.25 g g + 1.25 g = 450 2.25 g = 450 g = 200 then boys = 250 so there are 50 more boys than girls

**Physics**

I guess the wires have equal area A delta L = L * F/(EA) same for each so F/E must be the same for each F1/4 = F2/2 F1 = 2 F2 now moments about distance x from left where m is hung F1 * x = F2 (1.5-x) 2 F2 x = F2(1.5-x) 3 x = 1.5 x = .5 meters

**math**

one electrician would take 18 * 35 = 630 days so 28 electricians would take 630/28 = 22.5 days

**Algebra**

yes, difference is 1/8 or .125

**physics**

v = omega r = 3 so omega = 3/2.2 I = m r^2 = 46 * 2.2^2 L = I omega = 46 * 2.2^2 * 3/2.2 = 46 * 2.2 * 3

**physics**

change in rad/s = 1150 revs/min /1s = 1150 rev/min * 1 min/60 s * 2pi rad/rev /1 s

**Biomechanics**

h = 0 + 2.5 t - 4.9 t^2 0 = 0 +2.5 t - 4.9 t^2 4.9 t^2 - 2.5 t = 0 t (4.9 t - 2.5) = 0 t = 2.5/4.9 at max height, half that time h = 2.5(1.25/4.9) - 4.9(1.25/4.9)^2

**history**

yes, more people allowed to vote = more democracy