# Posts by Damon

Total # Posts: 29,990

**maths**

1.85 = (1+r)^5 log 1.85 = 5 log(1+r) use any base logs, base 10 or ln or whatever

**Physics**

assuming kilograms (please specify units) water is 4180 J/(kg deg C) heat into water = (0.1)4180*(32-20) Al is C J/(kg deg C) heat out od Al = .004(C)(100-32) so .004(C)(100-32)=(0.1)4180*(32-20)

**What do you think?**

I am not about to just answer this for you. Read about the difference between the economies of the North and the South.

**Math**

new length = 100 + 2 x new width = 50 + 2 x new area =(2x+100)(2x+50) so (2x+100)(2x+50) - 50*100 = 459 solve quadratic :)

**Chemistry**

Na = 23 g/mol Cl = 35.5 g/mol so NaCl = 58.5 g/mol so n = 42/58.5

**Chemistry**

heat generated = spec heat of water (202 grams)(27.33 - 25.00) divide by 1000 if that is in Joules to get kJoules divide by 2 grams to get kJ/gram

**Chemistry**

the gage pressure (pressure above one atm) would be (5/3)*1 atm but 1 atm = 101325 Pascals=101.325kPa so (5/3)(101) kPA if you want absolute pressure add 1 atm or 101 kPa to that

**Chemistry**

let C = specific heat of water heat gained = C*30*(T-280) heat lost = C * 50(330-T) so 30(T-280) = 50 (330-T)

**physics**

photon energy = h * frequency h = 6.626*10^-34 Joule seconds * 5.14*10^14 cycles/second

**Proof by contradiction**

Yes, however you do it, the vertex is above the x axis :)

**Proof by contradiction**

4x^2+1/4x <1 Can I simplify this inequality in the following way: multiply both sides by 4x so we have. 4x^2+1 <4x+1 ========================== I have no idea what you have and what you are doing. First of all, whatever, No If you have (4x^2+1)/4x <1 NOTE-parentheses ...

**Deduction**

deduction is incorrect draw Venn diagram we only know that the rainstorm is in the umbrella circle. He could easily carry the umbrella in a dry northwest breeze. hypothesis: If a cow, then a mammal Converse: If a mammal, then a cow (false) Inverse: If not a cow, then not a ...

**Physics**

Say the river runs south We want to end up going east Our velocity north will be 6 cos T - 3 = 0 if T is angle from north cos T = 1/2 T = 60 degrees from north which is 30 degrees from straight across

**Math**

| x - -2| = 3 is |x+2| = 3 try x = 1 try x = -5 :)

**calculus**

if y"'= -6 then y" = -6 x + c when x = 0, y"=2 = c so y" = -6x + 2 y' = -3 x^2 + 2 x + d y = -x^3 + x^2 + d x + e 1 = -1 + 1 + d + e 7 = -8 + 4 +2d + e so 1 d + e = 1 2 d + e = 11 ------------------ -d = -10 d = 10 so e = -9 and y = -x^3 + x^2 + 10 ...

**science (please please please help)**

I am no biologist but suspect you are right. Obviously the plant benefits from the N2 but I do not think the bacteria would be there unless they gained something (like a home). The other choices make no sense.

**Pre-Calc Trig**

well, where is the center of the wheel above ground? 12 + 67/2 = 45.5 = center above ground It does not say where the wheel starts so I will say it is at height = bottom now in general h = 45.5 + 33.5 sin( 2 pi t/T -p) where T is period in seconds and p is phase in radians Now...

**Math**

15*4*6 = 360

**HURRY MATH!**

$350/35hr = 10 dollars/hr -- correct

**Physics incomplete**

You have to know how far it is submerged m = 0.360 kg g = 9.81 m/s^2 tension = m g - buoyant force buoyant force = submersed volume * 900 kg/m^3 * g

**Math**

sides are x x-5 x-7 so 3x-12 = 42 3x = 54 x = 16 etc

**width typo**

I do not understand the width 1/1

**AP Physics**

positive is force up on feet 691 up - m g down = 0 if motionless if g = 9.81, m = 70.44 kg F - m g = m a where a is up 499 - 691 = 70.44 a a = -2.73 so accelerating down (negative a)

**physics**

change in velocity divided by time. (45-25)/10

**Math 8**

Two parallel lines never cross, no solution. y = 2 x - 4 y = 2 x + 4

**Social Studies**

Agree, if you lose 20 people in one fire they are probably crowded into tiny spaces.

**physics**

m g h = 6 * 9.81 * 12 Joules

**Math**

commission per CD = .08*12 = .96 so 52.8/.96

**Calculus**

(1/2)x^2+2x at 4 - at 1 = 8+8 - 1/2 -2 = 13.5 assuming by under you mean below the line and above the x axis

**Math**

(b-7)(s-7) = 72 b = s+6 so (s+6-7)(s-7) = 72 (s-1)(s-7) = 72 s^2 - 8 s + 7 = 72 s^2 - 8 s - 65 = 0 (s-13)(s+5) = 0 s = 13 then b = 19

**physics**

500 = m (heat of fusion + specific heat of water*4 deg)

**AP physics (simple experiment question)**

yes, you have the idea. The points on the bar that do not move are the nodes. The sand flies off the rest of the bar.

**AP physics (simple experiment question)**

google beat frequency eg http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/beat.html google nodes normal modes eg http://en.wikipedia.org/wiki/Normal_mode

**Math- Ms. Sue? Steve? Writeacher?**

(4,2) is in the first quadrant (5, -3) is in fourth quadrant, lower right across y axis, same y, change sign of x (-5,-3) quadrant III

**Physics**

time = 1/frequency = 1/(2.7*10^9) =(1/2.7)* 10^-9 seconds distance = speed*time = 3*10^8 *(1/2.7)(10^-9) = about 0.1 meter = 10 cm

**Maths**

You need as many equations as unknowns. Here yoou have 3 unknowns and two equations so no unique solution. There are two basic ways: 1, substitution, for example say s = 100 - (c+h) and use that for ss in the next equation so 40[ 100-(c+h) ] +65 c + 2 h = 3279 now you do not ...

**Proof by contradiction**

what happens if x > 0 ? what happens if x < 0 ? what happens if x = 0 ?

**physics**

average speed across window = 1.3/.22 = 5.91 m/s speed at top of window = Vt speed at bottom of window = Vb in general v = Vi + g t = Vi + 9.81 t so Vb = Vt + .22*9.81 = Vt + 2.16 Vt+Vb = 2 Vt + 2.16 (1/2)(Vt+Vb) = Vt + 1.08 = 5.91 so Vt = 4.83 m/s how far did it drop from a ...

**physics**

mass times acceleration. Your units are correct and your answer will be in Newtons of force. However m/s^2 not m/s2. The convention online is to write exponents as ^

**Math**

y = x^3

**social studies**

Agree first two. I think you are right about Paraguay as well, 1811.

**Math**

y = amount at end of every week after 4 weeks = 1700 + 200 (x-4) so y - 1700 = 200(x-4)

**Math**

draw triangle 40 + 50 + p = 180 p = 180 - 90 p = 90

**world history**

First you decide, then perhaps someone will review your answer. What do you think and why?

**Precal**

Now this is just like the other one (cos x/sin x)^2 - (1/sin x)^2 = (cos^2 x - 1)/sin^2x = sin^2 x / sin^2x = 1

**Calculus**

This is an odd function so its integral from -1 to +1 will be zero but anyway find average value on that interval that is the integral /(1 - -1)= integral/2 integral = (1/4)x^4 - 8x^2 from -1 to + 1 = 1/4-8 -(1/4)+8 = 0 so where is the function zero? at x = 0 of course I think...

**Physics**

I already did this http://www.jiskha.com/display.cgi?id=1491155418

**algebra 1**

the van uses 1 gal/20 mi so amount used = x/20 the tank holds V gallons so amount remaining after x miles y = V - x/20 we are given a point on that line 10 = V - 120/20 V = 10 + 6 = 16 gallons so in the end y = 16 - x/20

**Maths**

I am going to guess that your mean: 1/(1-x) + 2/(1+x) multiply tops and bottoms by [(1-x)(1+x)] [(1+x) + 2(1-x) ] /(1-x^2) **** remember a^2-b^2 =(a-b)(a+b) *** = [3 - x]/(1-x^2)

**Physics-Graivty**

F = G m M/r^2 F' = G m 2M/(2r)^2 F'/F = 2/4 =1/2 700* 1/2 = 350 N

**Physics**

100 = V i so i = 100watts/110 volts=about 1 coulomb/second (you use calculator) e = 1.6*10^-19 coulomb so (1/1.6)*10^19 electrons/second so 800 hours = 800*3600 seconds = 8*3.6*10^5 seconds so (8*3.6/1.6)* 10^24 electrons (quite a few)

**11 grade / physics**

5 kg*40cm = m kg *30 cm m = 5(4/3) = 20/3 kg

**Trig**

volumes of similar objects have dimensions proportional to length dimension cubed 800/2700 = 8/27 = 2^3/3^3 = (2/3)^3 so (2/3)15= 10 inches radius

**Physics**

(1/3)^2 = 1/9 so r = 3 re from earth center=19200 subtract re to get above surface so 19200-6400= 12800 km

**statistics**

like permutations = 10!/(10-3)!

**Geometry**

6 in expands to 36 in that would be times 6 10 in expands to 48 in that would be times 4.8 so the 10 inch dimension is limiting and the scale ratio is 4.8 6*4.8 = 28.8 inches so what is used is 28.8 in x 48 in

**Chemistry**

N = 14 g/mol O = 16 g/mol 2 Mols N2O5 = 56+160 = 216 grams 1 mol O2 = 32 grams so 32 grams O2 for each 216 grams N2O5 so (32/216)44.2

**math**

If you want the length of the mast and not the height, subtract 24 ft from the height.

**mechanics**

impulse is change of momentum .75 * 7 kg m/s or Newton seconds final speed/initial speed = 2/5 (1/2) .75 (25) (1/2) .75 (4)

**Hey, come on**

been there, done that.

**physics**

initial momentum north = final momentum north so 6,000*5 = 10,000* Vn same for west 4,000*15 = 10,000* Vw speed = s = sqrt(Vn^2+Vw^2) tan angle north of west = Vn/Vw initial Ke=(1/2)[6000*25+4,000*225) final Ke = (1/2)(10,000)s^2

**Not possible**

unless it has rocket propulsion it will not drop from 8 and rebound to 12

**geometry**

mast casts a 96 foot shadow? mast height = 24 * (96/64)

**PHYSICS**

the force is the same in each so add the extensions: mg/k1 + mg/k2

**physics help**

force = mass * centripetal acc = m v^2/r c = 2 pi r = 2 pi * 1.8 v = (c/6.2) meters/second so F = 20 * (c/6.2)^2/1.8 when F = mu * m g, we slip mu = Ac/g= (c/6.2)^2/(1.8*9.81)

**calculus**

Well, supposed to be your words, not mine. If a variable y depends on x as a continuous smooth function y = f(x) and we want to find the rate of change of y as x changes then on a graph, that is the slope of a tangent to the function, change in y / change in x at the point (x,...

**Physics**

dv/dt = 9 - 12 t and v(0)= 0 v = 9 t - 6 t^2 + constant when t = 0, v = 0 so constant = 0 v is radians/sec v = 9 t - 6 t^2 at v = 0 0 = t(9-6t) so v = 0 at t = 0 as we knew and v = 0 at t=9/6 = 3/2 = 1.5 so how far did it go? x is radians x = (9/2) t^2 - (6/3)t^3 + 0 x = (9/2...

**check your wording**

It is probably the minimum speed you mean. The centripetal acceleration must be at least 9.81 m/s^2 on earth or the string will go slack and the ball will fall on your head. Now you have given enough information already to find out. By the way, any old mass m will do v^2/r>...

**Math**

At the same store, Peter bought 2 pairs of pants and 5 shirts for $61, and jissica bought 3 pairs of pants and 2 shirts for $64. How much does 1 pair of pants cost? ~Please explain this problem to me

**Math**

60 - 24 = 36 points needed 36/4 = 9 questions needed right so n >/= 9

**Precalculus**

first do the complex conjugates (x+7i)(x-7i) = x^2 + 49 now the first two terms x^2-8x+16 now multiply using distributivee property x^2 ( x^2-8x+16 ) +49 ( x^2-8x+16 ) add

**PHYSICS**

50 = T1 cos 30 + T2 cos 60 T1 sin 30 = T2 cos 60

**Physics**

I guess 1 MJ means 10^6 Joules???? watts * seconds = Joules so 338 watts * time in seconds = 4.8*10^6 Joules t = 4.8 *10^6 / 338

**Physics**

http://hyperphysics.phy-astr.gsu.edu/hbase/Sound/dopp.html

**help math!**

distance home to store = d total time = 1 hr d = 15 t d = 10(1-t) 15 t = 10 -10 t 25 t = 10 t = 10/25 d = 15* 10/25 d = 6 miles each waay total distance = 12 miles total time = 1 hour so average speed = 12 miles per hour BY THE way AXENMO averaging the speeds them selves is ...

**help with math!**

Very much like your other problem total distance = 15(40/60) + 10(20/60) = 10+10/3 = 40/3 miles in one hour = 13.3 miles per hour

**Math**

2/1.5 = 4/3 = 16/12 1.5/2 = 3/4 =9/12 1/3 = 4/12 No constant ratio in this whole scheme so no proportionality

**physics**

moments around pivot point at 20cm m(50-20)+50(30-20)=100(20-10) 3m + 50 = 100

**physics question**

m Ac = m v^2/r = 1700 * 400 / 55 Newtons

**PHYSICS**

8.88*9.81/.0454 = 1919 N/m if you really want kilo Newtons then 1.918 kN/m

**physics**

F = m v^2/r = m omega^2 r m = 20 v = 2 pi r/6.2 = 2 pi(1.8/6.2) r = 6.2 so solve for F, the mass times centripetal a mu = Ac/9.81 = (v^2/r) /9.81

**Mathematics**

(x-1) is the altitude I assume? if so (x-1)(1/2)(x+6+3x-4) = 119 (x-1)(4x+2) = 119*2 (x-1)(2x+1) = 119 2x^2 - x - 120 = 0 (x-8)(2x+15) x = 8

**whoops, misread**

Just TEN cars 10 log 10 = 10 so ten dB for 10 times intensity so 90 db each

**NO!!!!!**

change in dB = 10 log base ten (intensity ratio) = 10 log (100) = 10*2 = 20 db for ten times intensity so 80 dB each

**Algebra error repair**

2 g t + g = 40 t (40 -2g)t = g t = g/(40-2g)

**Physic**

t is time for ball 2 t+1 is time for ball 1 h = (1/2)g (t+1)^2 h = 20 t + (1/2)gt^2 so g(t+1)^2 = 40 t + gt^2 g(t^2 + 2 t + 1) = 40 t + g t^2 2 gt + g = 40 t t = g (2t+1)/40 t+1 = answer to 1) etc

**Math 120**

first one: 4/10 second one 3/9 third one 2/8 fourth one 1/7 now multiply :) ------------------------ ow all good first one 6/10 second one 5/9 etc

**Physics**

energy at top = (1/2)m v^2 + m g h = 75 (25/2+9.81*7) energy at bottom the same but h = 0 so 75 (V^2/2) = 75 (25/2+9.81*7) (note-- the mass does not matter) Now if he comes up to the same height on the other side he will be moving up at 5 m/s (1/2)(25) = 9.81 h where h is the ...

**wrong I think**

V = Vi (0.82)^t not times t .75 = .82^t log .75 = t log .82 t = log.75 / log.82 = 1.45 years

**angular accleration**

Hey, I did one for you. Now you try.

**angular accleration**

150 - 120 = 30 rpm 30 *2pi/60 = pi radians/second = change in angular velocity pi/30 = angular acceleration in radians/second

**MATH: Check my answers | HELP ASAP!!**

12*23 = 276 yes

**US History UGGGH**

I am inclined to agree with you on d.

**Maths**

say tthey startedd east east distance = 150 + 120 cos 45 north distance = 120 sin 45 hypotenuse = sqrt[(150+120cos45)^2+(120sin 45)^2]

**Maths**

LOL try a+b+c = 3 try a = 1 b+c = 2 let b= 1 and c = 1 (1+1+1+1)(1+1+1+1) = 4*4 = 16

**Physics**

8.99*10^9[-32*10^-12 / 5.76*10^-4] = -49.9 *10^1 = -500 agree force is attractive (opposite signs). I guess you could call that negative.

**Physics**

v^2/R = 100/80

**science, maths**

the work done on a test charge q moving in an electric field is the force q*E times the distance moved IN THE DIRECTION of the force. The only direction that has NO component of force in the direction of motion is in the direction perpendicular to the force. The force is in ...

**math**

small = 47/22 - 11/22 = 36/22 = 18/11 large = small + 40/11

**modern physics**

I looked through this list of questions. They are cookbook questions and the recipes are in the student's text. for example if we know a half life in seconds and it is exponential decay then amount = original amount *e^-kt if amount/original amount = 1/2 then 1/2 = e^-kT ...