Friday
October 24, 2014

Posts by Elena


Total # Posts: 4,334

Physics
n=2.7 rev/s => ω=2πn=2•3.14•2.7 ≈17 rad/s ma=F(fr) mω²R=μmg μ=ω²R/g =17²•0.026/9.8 =0.77
June 8, 2013

physics
F=ma F=eE ma = eE a=eE/m= 1.6•10⁻¹⁹•10³/9.1•10⁻³¹= =1.76•10¹⁴ m/s² s=v₀²/2a = v₀²m/2eE= =(5•10⁶)²•9.1•10⁻³¹/2•1.6•10⁻¹...
June 8, 2013

Physics
under the action of a torque the dipole aspires to be established along the field
June 8, 2013

Physics
under the action of a torque the dipole aspires to be established along the field
June 8, 2013

Physics
v₀=110 km/h=30.6 m/s s=v₀t-at²/2, a=2(v₀t-s)/t²=… v= v₀-at=…
June 7, 2013

Honors Physics- Help PLEASE- Test tmrw
E=Δm•c²= =9.106•10⁻³•1.67•10⁻²⁷•(3•10⁸)²=1.37•10⁻¹²J
June 4, 2013

Physical Science
1A, 2B, 3B,D 4A, 5D, 6D, 7A, 8 ??? λ=v/f
June 4, 2013

Physical Science
1C. at a particular instant. 2A. 4 meters 3B. how fast a velocity is changing at a specific instant 4D. all of the above 5A. the amount of time needed to travel the distance. 6D. The train’s acceleration is negative. 7D. by adding the vectors
June 4, 2013

physics
ω=2π/t, v= ωR, R= v/ω=vt/2π= =24•0.1/2π=0.38 m.
June 4, 2013

PHYSICS
σ=F/A=F/πr² ε=ΔL/L Hook’s law for the wire: k ε= σ k= σ/ ε= F L /πr²ΔL E=k•ΔL²/2= F• L•ΔL²/2πr²ΔL= =F•L•ΔL/2πr²=49•5•10⁻...
June 3, 2013

Difracction problem
For CuKα-radiation λ=1.541•10⁻¹⁰ m. From equation sin²θ₁/(h²+k²+l²)₁=sin²θ₂/(h²+k²+l²)₂=…. const, sin²θ₁/1= sin²θ₂/2= sin²θ...
June 2, 2013

Physics 1 College Level
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², mg =GmM/R², g =G M/R²= =6.67•10⁻¹¹•77.89•10²³/(7.9•10⁶)²= =8.32 m/s²
June 1, 2013

Physics 1 College Level
R=sqrt(D²+d²)=sqrt(3204²+1247²)=3438 m The angle between R and D is cos α =D/R =3204/3438 α=21.26⁰ mass of the spaceship m=? mass of asteroid M=? F₁=GmM/R²=… F=2F₁cos α=…
June 1, 2013

physics
Q=cmΔT=1800•7•(70-35)=441000 J
June 1, 2013

physics
F•Δt=Δp=m•Δv= m(v-0) v= F•Δt/m = 80•0.04/0.058=55.17 m/s
June 1, 2013

physics
sinα =F₁/F₂=0.5 α= 30⁰, the angle between the two forces = 90⁰+30⁰=120⁰
June 1, 2013

MIT 2.01x
http://aerostudents.com/files/materialsAndStructures/Hibbeler8thEditionBookSolutions/Chapter%2005.pdf
May 31, 2013

Phyics help please varify the answer is correct
If RT ia the total R then Rt increases
May 31, 2013

physics please need help
tanφ=X(L)/R = 250/125 = 2 φ=tan⁻¹2=63.4⁰
May 31, 2013

Mathematics Ms Sue help
band-pass filter http://www.ibiblio.org/kuphaldt/electricCircuits/AC/AC_8.html
May 31, 2013

physics please need help
f=1/T=1/10⁻³=1000 Hz
May 31, 2013

Phyics please help ms sue
An open resistor is a resistor with one of the leads not connected.An open resistor can have no current or voltage, and it can have no effect on any circuit. => 35 Ω and 55 Ω are shorted and 100 Ω is open => ℰ=IR =100•10⁻³• 90 = ...
May 31, 2013

Phyics please help ms sue
W = Watt (unit of power) Resistance: Ohm =Ω => total resistamce R=100 Ω+35 Ω+55 Ω=190 Ω According to Ohm's Law ℰ=IR =100•10⁻³•190 =19 V ≠ 9 V.
May 31, 2013

physics
ma=F mv²/R=qvBsinα circular path = >sinα = 90⁰ q=e= e =1.6•10⁻¹⁹ C, m=9.1•10⁻³¹ kg R=mv/eB = =9.1•10⁻³¹•3•10⁷/1.6•10⁻¹⁹•0.2 = …
May 31, 2013

physics
Q=0.75V²t/R= =0.75•120²•15•3600/144=4050000 J = 4.05 MJ
May 30, 2013

Physics
φ=ω₀t-εt²/2 ω =ω₀-εt ω=0 ω₀=v/r φ=2πN ε =ω₀²/2φ =v²/2r²•2πN= = v²/4πr²N=36²/4•π•0.3²•40=28.6 rad/s²
May 30, 2013

physics
E=mc²
May 29, 2013

physics
E=mc² m=E/ c²
May 29, 2013

physics
β= v/c=0.3c/c=0.3 L=L₀•sqrt{1-β²)=30•sqrt(1-0.3²)=28.6 m
May 29, 2013

physics
t=t₀/sqrt{1-β²)=11/sqrt(1-0.7²) = 15.4 s
May 29, 2013

physics
P=F/A=NW/A N=PA/W = =1.013•10⁵•0.203•0.089/17.8=102.8 ≈103
May 28, 2013

English
These are questions from Stephen King's collection  "different seasons", particularly the novel "Rita Hayworth and the shawshank redemption": 1. From all the appearances the trial against Andy was pretty much "opens & shut". Identify the ...
May 28, 2013

Physics
h=v₀t+gt²/2 gt²+2 v₀t-2h=0 10 t²+3.4t-90 =0 t= {- 3.4±sqrt(11.56+3600)}/20= = { - 3.4 ± 60.1}/20 t = 2.83 s
May 28, 2013

physics
P=W/A= W/4πr², W=4πr²•P= =4•3.14•(6.37•10⁶)²•1.01•10⁵=5.15•10¹⁹ N
May 28, 2013

Physic Please Help
sqrt =square root, arctan = tan⁻¹ - inverse trigonometric function – (Broken Link Removed)
May 28, 2013

Physic Please Help
v=sqrt{(pl)²+v(wind)²} = ... α= arctan{ w(pl)/v(wind)}=... north of west
May 28, 2013

Physics ASAP
http://www.physicstutorials.org/home/mechanics/1d-kinematics/projectile-motion?start=1
May 28, 2013

Physics ASAP
t =sqrt(2h/g) s =vt
May 28, 2013

physics
ΔV/V = αΔT, ΔT = ΔV/ α•V= =0.0015V/V•5.1•10⁻⁵= =0.0015 / 5.1•10⁻⁵= 29.4, t=20+29.4 =49.4℃
May 28, 2013

physics
p= m₁v₁-m₂v₂= 1500•20 - 950•26 = = 30000- 24700 =5300 kg•m/s
May 28, 2013

physics
0=m₁v₁cosα + m₂v₂. v₁= - m₂v₂/m₁ cosα= = - 1.25•4/0.60•cos30 = - 9.62 m/s
May 28, 2013

Physics Acceleration
Δp=p₂-(-p₁) = p₂ + p₁ = m(v₂+v₁), F= Δp/Δt=ma , m(v₂+v₁)/Δt = ma, a= (v₂+v₁)/Δt= =(46+38)/1.05•10⁻³=8•10⁴ m/s²
May 26, 2013

physics
mg´=mω²R₂=m4π²R₂/T², g´=4π²R₂/T², mg´= G•m•M/R₂², mg= G•m•M/R₁², mg´/mg = G•m•M•R₁²/R₂²•G•m•M, g´/g...
May 26, 2013

PHySICS
x=kLλ/d λ=xd/kL= =4.2•10⁻³•1.15•10⁻³/3.9•2=6.2•10⁻⁷ m red
May 26, 2013

Physics
F(1x)=F(1)=10 N F(2x)=F(2)cos60=5•0.5=2.5 N F(2y) =F(2)sin60 = 5•0.866= 4.33 N F(3x) =- F(x)=- (10+2.5 )= -12.5 N F(3y) =- F(2y)= - 4.33 N F(3) = sqrt{ F(3x)²+F(3y)²} =13.23 N tan φ = F(3y)/F(3x) =4.33/12.5=0.364 φ = 19.1⁰ (south-west)
May 25, 2013

Physics
s=BC=1 m a) PE=KE₁ mgh = mv₁²/2 v₁=sqrt(2gh)=… b,c) KE₂=PE(spring) mv₂²/2 =kx²/2 v₂=sqrt{ kx²/m} =… KE₁=W(fr)+KE₂ mv₁²/2 = μmgs+ mv₂²/2 μ=(1/mgs)•{ mv₁²...
May 25, 2013

Physics
The circumference of the axel is L=πd, the string wraps around the axel N=s/L= s/ πd. The angle of rotation is φ=2πN=2 πs/ πd=2s/d= =2•80/2=80 rad
May 25, 2013

science
L=vₒ²•sin2α/g= vₒ²•2sinα•cosα/g h= vₒ²•sin²α/2g, h/L = vₒ²•sin²α•g / vₒ²•2sinα•cosα• 2g= =tan α/4=tan45/4=1/4=0.25 h=0.25L=0.25...
May 22, 2013

Physics
h= gt²/2 => t=sqrt{2h/g}, s=vt
May 22, 2013

physics
Q=IVt=(q/t)Vt=qV=eV= =1.6•10⁻¹⁹•9=1.44•10⁻¹⁸J.
May 22, 2013

Physics
http://web.mit.edu/8.02t/www/materials/StudyGuide/guide02.pdf
May 22, 2013

HELP pyhsic please (critical density)
http://m.teachastronomy.com/astropedia/article/Critical-Density
May 21, 2013

Physic problem(2)...Please help
In vector form: Δp⃗ =p₂⃗-p₁⃗ =mv₂⃗-mv₁⃗, for magnitudes Δp =p₂-(-p₁) =mv₂+mv₁= 2mv. p=Mu => Mu=2mv The speed of the center of the door is u=2mv/M=2•0.4•35/15 = 1.37 m/s Its ...
May 21, 2013

Physics
The angular momentum of the door ‘p’= the change in amgular momentum of the ball Δp. In vector form: Δp⃗ =p₂⃗-p₁⃗ =mv₂⃗-mv₁⃗, for magnitudes Δp =p₂-(-p₁) =mv₂+mv₁= 2mv. p=Mu...
May 21, 2013

Physics
http://www.jiskha.com/display.cgi?id=1368801920
May 21, 2013

physics
p=W/A =W/a²=75/0.01=7500 Pa
May 21, 2013

physics
N=mg => m=N/g = 95/9.8 =9.69 kg
May 21, 2013

physics
s₁=v²/2a₁=28.8²/2•4=103.7 m. s₁=a₁t₁²/2 => t₁=sqrt(2s₁/a₁) =sqrt(2•103.7/4) =7.2 s. t₂=63.8 s. s₃=v²/2a₃=28.8²/2•1.58=262.5 m s₃=a₃t₃²/2 => t...
May 21, 2013

physics
s=at²/2=100•25/2=1250 m
May 21, 2013

PHYSICE
http://teacher.pas.rochester.edu/phy121/lecturenotes/Chapter13/Chapter13.html
May 21, 2013

physical science
ΔKE =Work mv₂²/2 - mv₁²/2 = W v₂= sqrt{(2/m)•[W+ mv₁²/2]}=…
May 20, 2013

physics
a=eE/m s=v²/2a
May 20, 2013

Physics
t=sqrt{2h/g} v=L/t
May 18, 2013

physics
φ=31⁰π/180⁰ = 0.54 rad. n = 900 rev/min =900/60 =15 rev/s t=φ/ω= φ/2πn=0.54/2π•15=0.006 s v=d/t =0.8/0.006 = 133 m/s
May 18, 2013

physics
See my answer to a similar question below under related questions.
May 18, 2013

Physics
t=sqrt{2h/g}
May 17, 2013

physics
D) {4•100 +4•80} – sqrt(400² +80²) = 72 m
May 17, 2013

physics
Upward motion: h=v₀t-gt²/2 v= v₀-gt v=0 => t=v₀/g h= v²/2g =30²/2•9.8=45.9 m t=sqrt{2h/g} =sqrt{2•45.9/9.8} = 3.06 s. t(total)=2•t = 2•3.06 =6.12 s.
May 17, 2013

science-physics
W•0.67 = 183•(1.4-0.67) +107•(2.8-0.67) W={183•0.73+107•2.13}/0.67=540 N
May 15, 2013

Physics
λ =v/f=330/320 = ... m
May 15, 2013

physics
Velocity in the stretched string is v = sqrt(TL₀/m) = =sqrt(570•0.92/0.0037) = 376 m/s, λ =2L =2•0.65 = 1.3 m, λ = v/f => f=v/λ =376/1.3=289 Hz.
May 14, 2013

Physics
mgh = mv²/2 v=sqrt{2gh}
May 14, 2013

Physics helpp
F-F(gr) = ma a= {F-F(gr)}/m = =(15-10)/15=0.33 m/s² (upward)
May 14, 2013

science physics
1,2). k =9•10⁹ N•m²/C², q₁=5 C, q₂= - 2.5 C. F=k•q₁•|q₂|)/r² = =9•10⁹•5•2.5/1.75² =3.67•10¹⁰ N (to the right). 3). E=k|q₂|/r² =9•10⁹•2.5/1.75&#...
May 14, 2013

physics
k =9•10⁹ N•m²/C² F=k•q₁•q₂/r² = =9•10⁹•5•2.5/1.75² =3.67•10¹⁰ N (to the right)
May 14, 2013

physical science
a=F/m = 14000/2500 =5.6 m/s^2
May 14, 2013

Physics
m=14 kg F=ma=14 x 1.5 = 21 N
May 14, 2013

Physics to Elena
(a) The time-averaged Poynting vector is <S> =cε₀E₀²/2. The amplitude of electric field is E=sqrt{2<S>/ cε₀} = =sqrt{2•1.35•10³/3•10⁸•8.85•10⁻¹²} = 1.01•10³ V/m. (b) The ...
May 14, 2013

Physical Science
KE=mv²/2 m= ρV kinetic energy per unit volume V KE₁ =KE/V= mv²/2V =ρV•v²/2V = ρv²/2
May 13, 2013

Physical Science
KE=ρv²/2= 1•10³•0.5²/2=125 J
May 13, 2013

physics
Coulomb’s Law: F=k•q₁•q₂/r² =… F=ma => a=F/m=… r=at²/2 t=sqrt{2r/a)=…
May 13, 2013

physics
F(BC) =kq²/a² q´(B)=q´(A) =(q+0)/2=q/2, q´´(A) =q´(C) = {q´(A)+c(C)}/2 = 3q/4 F´(BC) =k q´(B)• q´(C)/a² = =(3/8)• kq²/ a²=3•4/8=3.2 = 1.5 N
May 13, 2013

physics/chemistry(kinetic ..gasses)
<v> =sqrt{3RT/M}=sqrt{3pV/m} => M=mRT/pV =ρRT/p. v=sqrt {γRT/M}. γ=C_p /C_v = (i+2)/i. v=sqrt{9i+2)RT/iM} = sqrt{(i+2)RTp/iρRT}= =sqrt{(i+2)p/iρ}, iρv² - ip = 2p, i=2p/ (ρv² - p) = =2• 1.01325• 10⁵/(1.3&#...
May 13, 2013

Physical Education
mg=F(buoyant), ρ₁Vg=ρ₂0.64Vg, ρ₁=0.64ρ₂=0.64•806=515.84 kg/m³.
May 13, 2013

physics
F(BC) =kq²/a². q´(B)=q´(A) =(q+0)/2=q/2, q´´(A) =q´(C) = {q´(A)+c(C)}/2 = 3q/4, F´(BC) =k q´(B)• q´(C)/a² = =(3/8)• kq²/ a²=3•4/8=3.2 = 1.5 N
May 12, 2013

physics
s=v•t=...
May 12, 2013

Physics
eU=mv²/2 v=sqrt{2eU/m} = sqrt{2•1.6•10⁻¹⁹ •750/5.2•10⁻²⁷) =6.7•10⁴ m/s mv²/R=evB R=mv/eB =5.2•10⁻²⁷•6.7•10⁴/1.6•10⁻¹⁹•0.65 = 3.4•10...
May 11, 2013

Physics
F=ma=evBsinα a= evBsinα/m =1.6•10⁻¹⁹•7.5•10⁶•0.04•sin50/9.1•10⁻³¹= 4•10¹⁶ m/s²
May 11, 2013

physics
A=0.1 m ω=sqrt(k/m) =sqrt(100/4) =5 rad/s v(max) =Aω =0.1•5=0.5 m/s
May 11, 2013

ThermoPhysics
Adiabatic index γ=(i+2)/i=(5+2)/5= 1.4. (a) p₁(V₁)^γ=p₂(V₂)^γ V₁/V₂ =( p₂/p₁)^(1/ γ)=20.5^(1/1.4)= =20.5^(0.714)=8.65. (b) (p₂/p₁)^(γ-1) = (T₂/T₁)^γ (T₂/T₁) =((p&#...
May 11, 2013

Physics
a=v²/2s=... s=at²/2 => t=sqrt{2s/a)=...
May 11, 2013

Physics
I=8.28•10⁻³⁸ g•cm²=8.28•10⁻⁴⁵kg•m², I=2mr²/3 => radius of diatomic molecule r=sqrt{3•I/2m} Root mean square speed v =sqrt{3kT/m}. v = ωr. Angular root mean square speed ω=v/r= =sqrt{2kT/I...
May 10, 2013

Physics: Manitude of Surface Charge on Dielectric
If the electric susceptibility κ=4.5, electric permittivity is ε = κ+1 = 5.5 C₁=q₁/V, q₁=C₁V=1.86•10⁻⁶•12=2.23•10⁻⁵ C, C₁=ε₀A/d = q₁/V, C₂=εε₀A/d = q&#...
May 10, 2013

Physics: Capacitance of Capacitor
Q₁=Lf•m = C₁V²/2 Q₂=Lv•m = C₂V²/2 Lf•m/ Lv•m=2C₁V²/2 C₂V² C₂=Lv•C₁/Lf = 22.6•10⁵•8/33.5•10⁴= 53.97 μF
May 10, 2013

Physics: Potential Difference
C₂=kC₁ Energy = CV²/2 C₁V₁²/2=C₂V₂²/2 V₂=V₁/√(k)=15/√(3.6) = 7.9 V
May 10, 2013

Physics: Dielectric Constant
C=εε₀A/d ε=Cd/ε₀A = =9.1•10⁻⁶•1.5•10⁻⁵/8.85•10⁻¹²•2 =7.7.
May 10, 2013

la porte high school
h= gt²/2, t=2h/g=2•12/9.8=2.45 s s=v•t = 15•t=15•2.45 = 36.7 m
May 10, 2013

physical
m=ρV=ρπr²h=1950•π•0.051²•0.003=0.048 kg
May 10, 2013

physics
The law of conservation of linear momentum m₁v₁- m₂v₂=(m₁+m₂)u u={m₁v₁- m₂v₂}/(m₁+m₂)
May 10, 2013

physics
F=kx k=F/x W=ΔPE= kx²/2=Fx²/2x= Fx/2=20•0.05/2=0.5 J
May 10, 2013

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