# Posts by Damon

Total # Posts: 31,643

**Physics**

Either way :)

**Physics**

acceleration = a = [ (2234-0) res/60s ] /.8s = 46.54 revs/s^2 revs = (1/2)a t^2 = (1/2)(46.54)(.64) = 14.9 revs

**Physics**

g = v^2/R

**Calculus**

I guess maybe assume straight shoreline running NW to SE

**Algebra 2**

in general though see: http://www.mathsisfun.com/algebra/matrix-determinant.html

**Algebra 2**

you could do (1*-3) - 7(0) = -3

**Calculus**

slope = 5 at x = 2 so y = 5 x + b -4 = 5 (2) + b -4 = 10 + b b = -14 so y = 5 x -14

**Math**

47+29 = 76 first one 47/76 second on 46/75 third one 45/74 fourth one 43/73 multiply :)

**math**

I assumed you put the first card back. If not then it becomes 12/51

**math**

The first draw is some suit. The probability that the second draw is that suit is 1/4 = 0.25

**Physics**

55 degrees with what?

**Physics 30 meter rod?**

Please proofread. Where does the string attach to the rod? What on earth do you mean by normal force on a string? Strings are usually in tension.

**Physics**

top at 3/2 = 1.5 s = t v = Vi - g t 0 = Vi - g t so g t = Vi = 9.81 * 1.5 = 14.7 h = Vi t -4.9 t^2 = 14.7 *1.5 - 4.9(2.25) = 22 - 11 = 11 meters note, same as average speed = 14.7/2 times 1.5 seconds

**that depends**

on what the total current is current = i = electron charge * electrons/second so electrons/second total = i/Qe per unit area i/(Qe area)

**Quadratic equations**

4.9 t^2 -24.5 t -29.4 = 0 t^2 - 5 t - 6 = 0 (t-6)(t+1) = 0 t = 6 seconds (the -1 second is before release :)

**10 volts * C = q**

but C times ten volts = q per capacitor

**physics**

C = q/V so q = C V so each stores 2.5 * 10^-12 C so we need 1.2*10^-6/2.5*10^-12 = .48*10^6 =480,000

**Physics - Vectors/Forces**

(6/10) 10 g = 6 g = 6*9.81 = 58.86 Newtons

**Math**

http://calc101.com/webMathematica/long-divide.jsp#topdoit 3 x - 1 and remainderr -4/(x+2) draw a diagonal

**Math**

[ 6*3 sqrt 3 - 3 sqrt 3 /4 ]^2 9*3 [6-1/4]^2 27 * 33.06 893

**Physics**

75 * g * 0.60

**Math**

5 * 5 = 25 .6 * 25 = 15 x^2 = 15 x = 3.873 meters

**Physics**

By the way those of us who do navigation have trouble with x, y rather than east, north

**Physics**

initial east,x, momentum = 7150(5) -1650(20)cos 30 = 7,171 initial north,y, momentum = 0 - 1650(20)sin 30 = -16,500 Those will not change during the collision so tan of angle south of east = 16500/7171 angle south of east = 66.5 deg Their answer, is 293.5 COUNTERCLOCKWISE from...

**Math**

15 x -20 y = 40 15 x + 9 y = 69 -------------------subtract -29 y = -29 y = 1 3 x - 4 = 8 3 x = 12 x = 4 x+y = 4 + 1 = 5

**physics**

omega = constant angular velocity v = omega r Ac = omega^2 r slips when mu m g = m omega^2 r or mu g = omega^2 r so the bigger r, the more likely the slip r = mu g/omega^2

**SAT Math**

You are welcome.

**SAT Math**

x = 28 w y = 3/(5w) x y = 28 w * 3/(5w} x y = 84/5

**Stats**

binomial p = .15 1-p = .85 C(12,6) = 924 so 924 * .15^6 * .85^6

**Physics**

whew, we agree :)

**Physics**

momentum of electron (say in x direction) Px = 9.11*10^-31 ( 4*10^7 ) = 36.44 * 10^-24 momentum of anti-n (say in y direction) Py = 4*10^-24 |P| =sqrt( Px^2+Py^2) = 10^-24 sqrt( 36.44^2 + 16) = 36.7 * 10^-24 so m v = 36.7*10^-24 2.34 * 10^-26 v = 36.7 * 10^-24 v = 15.7 * 10^2 ...

**physics**

initial speed = 100 final speed = 0 so average speed = 50 rad/s How long does it take? v = Vi - 6 t 0= 100 - 6 t t = 100/6 = 16.7 s so radians total = 50*16.7 divide by 2pi rad/revolution 50 ( 16.7) /6.28 = answer

**College Physics**

F = 2 * 424 * sin 30 = 424 F = m A A = 424/.055 = 7709 m/s^2

**Physics ????**

Where is the rest of the problem? Like how high did the mass rise with the bullet in it?

**electronics**

Parallel: impedance ----> infinity at resonance Series impedance ----> 0 at resonance (in reality to R because there is always some resistance)

**Physics**

v = 45 - 9.81 t = 45 - 9.81(2.55) = 20 m/s initial momentum up = 20 m final momentum up = 20 m = (1/2)m v cos 45 + (1/2)m v cos 45 final up = initial up m v cos 45 = 20 m v = 20/cos45 = 20 sqrt 2

**Physics**

current is Coulombs per second. What did you try to do?

**Physics**

energy to heat water in Joules = heat capacity*mass*change in temp electric energy in Joules = i*V * time in seconds

**Physics**

A = angle up u = 120 cos A 400 = u t = 120 cos A * t t = 400 / (120 cos A) Vi = 120 sin A v = Vi - 9.81 t 40 = Vi t -4.9 t^2

**Physics**

50 sin 20

**college physics**

or for d just use average speed during stop 5 * t

**college physics**

F = m A so A = -.057/.228 v = Vi + A t 0 = 10 - (.057/.228)t t = 2.28/.057 d = 10 t -(.057/.456) t^2

**Math**

100(27/36)

**Physics**

SW = 180+45= 225 degrees True south component = 450 cos 45 = 318 south west component = 450 sin 45 = 318 west S = 180 degrees True south component = 500 west component = 0 so total south = 318+500 = 818 total west = 318 total distance=sqrt(818^2+318^2) = 878 meters if A is ...

**Science**

(NO3)2 means NOOO NOOO which is 2 * 6*10^23 N atoms in a gram molecular mass (Mol) of Zn(NO3)2

**Math**

5 J = 80 J = 80/5 J = 16

**Physics**

40 km/h = 40,000 m/ 3600 s = 11.1 m/s 5 min = 300 s time to accelerate = t d1 = (1/2) a t^2 11.1 = a t so d1 = (1/2)(11.1) t d1 = 5.56 t runs at 11.1 m/s for t2 seconds distance = d2 = 11.1 t2 deaccelerate time = 3 t 0 = 11.1 + 3 a2 t a2 t = -11.1/3 = - 3.7 t a2 = -3.7/t d3 = ...

**b e t Sofia high school (arethametic)**

checking because have concern about form http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html a(n) = a(1) + (n-1)d .......Not a(0) q = a(1) + (p-1) d p = a(1) +(q-1) d p-q = d[ (q-1) - (p-1) ] p-q = d [q-p] d = -1 agree so a(n) = a(1) +(n-1)(-1) a(n) = a(1) + 1-n ...

**Physics**

sin 30/sin T2 = 1.5/1 sin T2 = .5/1.5 = .333... T2 = 19.5 degrees distance through glass at 0 degrees from normal is given = .02 meter distance throgh glass if NO refraction = .02 /cos 30 = .0231 meter actual distance through glass at 19.5 deg = .02 / cos 19.5 = .0212 meter if...

**Math**

minute hand does one circle, 2 pi radians, in an hour (50/60)*2 pi 7 * 2 pi

**CALC**

are you sure it is not y = x/(4-x^2) ? if so as x ---> 0 , y---> x/4 which is zero sort of a HA but not really, just an inflection point as x---> 2 or -2 y---> oo VA

**Science : physics**

F = d/dt(mv) = m a if m is constant rest mass a = v^2/r omega = angular velocity = 2 pi rad/rev *6.6*10^18 rev/s = 4.15 * 10^19 rad/s v = omega * r = 4.15 * 10^19 *6.1 = 25.3 *10^19 meters/second this is many times the speed of light which is about 3*10^8 m/s You could try ...

**STATISTIC MECHANICS**

X kilograms of ice SH means specific heat or heat capacity HF means heat of fusion Heat into ice = X(20)SHice + X(HFice) + X(40)SHwater = Heat out of water = 0.250(SHwater)(75-40)

**algebra**

Xn = a + (n-1)d X5 = a + 4 d X5 - 1 = 2 [ a + d ] X10 - 3 = 2 [ a + 3 d ] but X10 = a+9d so a + 4 d - 1 = 2 a + 2 d a = 2 d - 1 a + 9 d - 3 = 2 a + 6 d a = 3 d -3 combine 3 d - 3 = 2 d - 1 d = 4 You take it from there.

**math**

any x < 8 suspect typo

**Statistics**

.13 * .13

**Physics**

Power = i V 50,000 = i (5000) i = 10 amps Power lost = i^2 R = 100(20) = 2000 watts so Power received at factory = 50,000 - 2,000 = 48 kilowtts

**Math**

(x^2+1)/(x^2-1) = 221/220 220 x^2 + 220 = 221 x^2 - 221 x^2 = 441 x = sqrt(441) = 21

**Pre-calculus, typo (-1,1) maye?**

equation of that line is y=-3/2 x so slope = -3/2 eqn of circle (x-k)^2 + (y-h)^2 = r^2 2(x-k)dx +2(y-h)dy = 0 dy/dx = -(x-k)/(y-h) at (0,0) dy/dx = k/h = -3/2 say h= - (2/3 )k at (0,0) (x- k)^2 +(y+2k/3)^2 = r^2 but x = y = 0 k^2+4k^2/9 = r^2 13 k^2/9 = r^2 so (x- k)^2 +(y+2k...

**math**

4*1000 + c*100 + b*10 + a*1 c < 5 so 0, 1, 2, 3 or 4 c = 2 b so c is even, 0, 2, or 4 4 + c + b + a = 12 so c + b + a = 8 if c = 0 ,b = 0 because c=2b 4 0 0 4 does NOT add to 12. if c = 2 4 2 1 mope, only two digits allowed if c = 4 4 4 2 2 ah ha, 4422 seems to work

**Physics**

to melt ice at 0 C requires 334,000 Joules/kg so we use 501,000 Joules for melting at 0 C 501,000 = 5.01*10^5 so we still have 3.11*10^5 JOules to heta the water 4190 Joules to raise temp of 1 kg water 1 degree C so 311,000 = 4190 (1.50)(T-0) T = 311,000/ [4190*1.5 ]

**physics**

Perhaps you are accelerating it upward?

**Hey ! same as Bob Pursley answered**

This problem is just like the one Bob Pursley answered for you. Please try yourself!

**Physics**

initial ke = (1/2)mv^2 =.5*3*49 = 73.5 Joules slides for one meter, how much energy lost? mg = 3* 9.81 = 29.4 Newtons weight so mu m g = friction force = .26*29.4 = 7.65 N so friction work = 7.65 * 1 = 7.65 Joules lost to friction so ke at bottom of ramp = 73.5 - 7.65 = 65.8 J...

**calculus**

6 = a^2 -a - a a^2 - 2 a - 6 = 0 a = [ 2 +/- sqrt (4+24) ]/2 = 1 +/- sqrt 7 try both to make sure which works perhaps you left out a parenthesis or two though 6 = (x^2 -a^2)/(x-a) = x+a then if x = a 6 = 2a a = 3

**It is .5932 NORMAL APPROX**

mean = 5 sd = sqrt(5*.9) = 2.121 look for greater than 4.5 !!!!! use eg http://davidmlane.com/hyperstat/z_table.html

**physics**

well, 3 is the easiest of all. Thw impulse is the change of momentum.MV = 1 *10 = 10 kg m/s average speed during stop = 10/2 = 5 m/s so t = time to stop = 0.10 meter/ 5 meters/s = 0.02 second. That is number 2 a = change in v/ time = -10/.02 = -500 m/s^2 that is number 1...

**Physics**

let x be distance from hinge to point below other end of rod then height of end of rod above floor = sqrt(4-x^2) let y be distance down from ceiling to tip of rod then y = sqrt(6.25-x^2) so 3 = sqrt(4-x^2) + sqrt(6.25-x^2) sqrt(6.25-x^2 )= 3 - sqrt(4-x^2) 6.25 - x^2 = 9 -6sqrt...

**physics**

Period = 1/f = 1/20 second wavelength = period * speed = (1/20)(.15)

**AEJC , physics**

during the stop the average speed is 8/2 = 4 rps 11 r/4 r/s = 2.75 seconds to stop initial angular speed = 2 pi * 8 = 16pi = 50.3 radians/second = Vi v = Vi + a * t 0 = 50.3 + a * 2.75 a = - 18.3 radians/s^2 Torque = I a = I*= -18.3 I do not know the mass distribution of your ...

**maths**

You steer a heading, not a bearing. There is a conspiracy of inland math teachers trying to drive navigators crazy. North component of speed through water = 20 cos 136 = -14.4 km/hr East component of speed through water = 20 sin 136 = +13.9 km/hr North component of current = 5...

**Science**

v = Vi - 9.81 t at top v = 0 so t = 700/9.81 = 71.4 s now there are two ways to proceed one way: h = Vi t -4.9 t^2 h = 700(71.4) - 4.9(71.4)^2 h = 25,000 m other way; average speed up = (700+0)/2 = 350 m/s h = 350*71.4 = 25,000 m

**math**

each side of the big one is 4 times the one in the small triangle 4a+4b+4c = 4(a+b+c) the altitude of the big one is 4 timess the altitude of the small one (1/2)(4h)(4b) = (16) (1/2) a b

**You mean e^kt not e^k/t**

P = Po e^kt 400 = Po e^10k 1500 = Po e^35 t 1/Po = (1/400) e^10 k = (1/1500)e^35 k e^35 k / e^10k = 1500/400 = 15/4 e^25 k = 15/4 25 k = ln(15/4) = 1.322 k = .0529 so P = Po e^.0529 t 400 = Po e^.529 Po = 236 then P = 236 e^.0529 t I think you can take it from there

**Physics**

F = G M m /d^2 g = F/m = G M/d^2 on surface d is radius R so 9.81 = G Me /R^2 gv = GMv /R^2 = G (.8Me)/R^2 = .8* 9.81 them Wv = m gv = .8 We

**MATH HELP ASAP PLEASE!!!!!**

then divide both sides by 4 x > 0.3 now be careful, if you divide or multiply by a NEGATIVE number, you must change the direction of the arrow. However that is not the case here.

**MATH HELP ASAP**

well to make it easy 0.25 = 1/4 so (1/4) s = 50 s = 4 * 50 s = 200

**Science**

22.4 liters/mol calcium carbonate is 100 g/mol so we have 1/4 mol (1/4)(22.4) = 5.6 liters = .0056 m^3

**physics**

d = Vi t + .5 a t^2 runner 1 400 = 6 t and a = 0 t = 400/6 runner 2 400 = 10t - 0.9 t^2 .9 t^2 - 10 t + 400 = 0 solve quadratic t = complex number, never makes it :) The velocity turns negative before the runner reaches the finish Let's see when v = 0 v = 10 -1.8 t v = 0 ...

**Mathematics**

Jessica is correct.

**superb**

I am going to assume that you could not type = signs R = 0.30 meters Vt = 2t at t = 3 s Vt = 6 m/s dVt/dt = 2 m/s^2 so At = 2 m/s^2 Ar = Vt^2/R = 36/.3 = 360/3 = 120 m/s^2

**By inspection - first one**

many can be done faster by factoring though eg Solve. (-10x^3+30x-20) / (-5x+5) A) 2x^2-2x+4 B) -2x^2-2x-4 C) -2x^2+2x+4 D) 2x^2+2x-4*** =========================================== (2x^3-6x+4)/(x-1) (2x^2+2x-4) (x-1)/(x-1) so I agree By the way, where you type "where"...

**Math**

http://calc101.com/webMathematica/long-divide.jsp#topdoit

**Physics 11**

Yes, right idea. I did not check arithmetic.

**physics-density**

R = radius of cone height of cone = h draft of cone = x =distance below surface area of base = pi R^2 area of water plane = pi r^2 x/h = r/R geometry weight of cone = rho g(1/3)pi R^2 h weight of water displaced = 1000 g(1/3)pi r^2 x force up = weight of water displaced - ...

**Time rates**

The volume of anything pointy with straight sides is (1/3) base area * height so V = (1/3) pi r^2 h but h = 2 r so V = (2/3) pi r^3 find dr/dV, worry about dh/dV later (note h = 2 r) dV = (2/3) pi (3 r^2) dr = 2 pi r^2 dr dV/dt = 2 pi r^2 dr/dt = 10 m^3/min but r = h/2 and dr/...

**algebra**

5 n + 10 d + 25 q = 185 d = 2 q n = 2 d -2 = 4 q - 2 so 5 (4q-2) + 10(2q) + 25q = 185 ok from there?

**Algebra 1**

well first divide both sides by 5 1 x^2 + 1 x - 12 = 0 x = [ -1 +/- sqrt( 1 -4(1)(-12) ] / 2 x = [ -1 +/- sqrt(49)] /2 x = [ -1 +/- 7 ]/2 x = 3 or x = -4 CHECK 5*9 + 5*3 - 60 = ? 45 +15 - 60 = 0 sure enough

**Chemistry**

for electron lambda = h/mv = 6.63*10^-34 /[ 9.1*10^-31*6.68*10^5] = .109*10^-8 = 1.09 * 10-9 = 1.09 nm

**Chemistry**

A. ok I got 2.09*10^-19 J but used crude electron mass approx B. Ephoton = Eelectron + h * 5.5*10^15 Ephoton = 2.03*10^-19 + 6.63*10^-34*5.5*10^15 Ephoton = 2.03*10^-19 + 36.5*10^-19 Ephoton = 38.5 *10^-19 Joules now what wavelength is that E = h c/lambda so lambda = h c/E ...

**Algebra 2**

I agree.

**Algebra 2**

2 pi f x = x/4 so f = 1/(8pi) check when x = T , T/4 = 2 pi so T = 8 pi f = 1/T = 1/(8pi)

**Math**

What did you get ?

**Math**

4 x y z x = 2 y but x is <5 so y = 0, 1, or 2 4 + 2y + y + z = 12 so x + 3y + z = 8 if y = 0, then twice y is also 0 nope if y = 1, then twice y = 2, nope 421 three digits if y = 2 , then 4 4 2 z then if z = 2, the sum is 12 how about 4422 ???

**Physics**

rho water = 1000 kg/m^3 P1 + (1/2) rho V1^2 = P1 + (1/2) rho V2^2 and V1 A1 = V2 A2 so V2 = V1(100/25) = 4 V1 8*10^4 +(1/2)(10^3) V1^2 = 6*10^4 + (1/2)(10^3)(16 V1^2) solve for V1 then volume flow rate = pi R1^2 V1 or mass flow rate = 1000 pi R1^2 V1 note R1 = 0.10 meters

**Physics**

KE = (1/2) m v^2 dKE= (v^2/2)dm + mvdv dm = .02 m dv = .04 v dKE = (v^2/2) .02 m + m v .04 v = m v^2/2 (.02) + mv^2/2 (.08 ) = 0.10 KE = 10% because velocity is squared, it alone counts for 2*4 = 8%

**Physics**

They have the same mass. The force up on the wood block is m g the force up on the Al block is its volume * density of water * g but what is its volume? Al density = 2.7 * density water = 2700 kg/m^3 so volume = m/2700 so force up on Al is (m/2700)1000 g = m g/2.7 the force up...

**Physics**

A + B = 17 A - B = 7 2A=24 A = 12 B = 5 so sqrt(25+144)

**physics**

LOL try it with a mass on the spring as you compress it, U, the potential energy goes up when you release it the mass hits max velocity as it passes zero. then the kinetic energy dies and the potential climbs again U = (1/2) k x^2 x^2 is the same for + or - x A=B !!!!!

**Physics**

use dot product |A| |B| cos theta = A dot B = 36+64 -100 = 0 LOL, cos theta = 0 so theta = 90 degrees