Tuesday
March 31, 2015

Posts by Elena


Total # Posts: 4,364

physics
Describe the configuration of the bent wire
December 2, 2013

Physics
R=mv/eB m =9.1•10 ⁻³¹kg e =1.6•10⁻¹⁹ C.
December 2, 2013

magnetism and electricity
Desribe the configuration of the bent wire
December 2, 2013

physics
μ₀I₁/2πy= μ₀I₂/2π(0.28-y) I₁(0.28-y)= I₂y 30(0.28-y)=50y 80y=8.4 y=8.4/80=0.105 m
December 1, 2013

physics
r=d/2 =0.5 mm =0.0005 m I(max) = B(cr) c r /2 = 0.01•3•10⁸•0.0005 /2 = 750 A
December 1, 2013

Physics
a=(F-F(fr))/(m1+m2)
December 1, 2013

magnetism
r=d/2 =0.5 mm =0.0005 m I(max) = B(cr) c r /2 = 0.01•3•10⁸•0.0005 /2 = 750 A
December 1, 2013

magnetic field
μ₀I₁/2πy= μ₀I₂/2π(0.28-y) I₁(0.28-y)= I₂y 30(0.28-y)=50y 80y=8.4 y=8.4/80=0.105 m
December 1, 2013

physics
E=Pt/η=4500•20/0.9=100000 J =0.1 MJ
December 1, 2013

physics
μ₀I₁/2πy= μ₀I₂/2π(0.28-y) I₁(0.28-y)= I₂y 30(0.28-y)=50y 80y=8.4 y=8.4/80=0.105 m
November 30, 2013

physics-magnets
b=a•cos45 =0.1 •0.707 = 0.0707 m B=2 (μ₀/4π)(I/b)∫cosφdφ {limits: (- π/4) (+π/2)} =2(μ₀/4π)(I/b)(1+0.707)= =2.1414 •(μ₀/4π) •2/0.0707=6.06•10⁻⁶T
November 29, 2013

Physics -Solinoid
d)
November 29, 2013

physics
circle: L=2πR R=L/2π B₀=μ₀I/2R= μ₀I2 π /2L= =μ₀πI/L square: L=4a=> a=L/4 The distance from the center of the square to the midpoint of the side of the square is b=a/2tan45=a/2 B⋄=4B₁=4B= =4(μ₀...
November 29, 2013

magnetism
μ₀I₁/2πy= μ₀I₂/2π(0.28-y) I₁(0.28-y)= I₂y 30(0.28-y)=50y 80y=8.4 y=8.4/80=0.105 m
November 29, 2013

Math
a. t > w
November 29, 2013

Math
B. w > t
November 29, 2013

math
sin φ=h/L h=Lsin 30=L/2
November 29, 2013

physics
KE=mv²/2 “v” is the speed of the ball in the frame of reference “connected with” the airplane
November 29, 2013

physics
ΔE=hf f= ΔE/h=0.33•1.6•10⁻¹⁹/6.63•10⁻³⁴ = =7.96•10¹³ Hz
November 28, 2013

physics
E=hf=6.63•10⁻³⁴•1.7•10¹³=1.13•10⁻²⁰ J= = (1.13•10⁻²⁰/1.6•10⁻¹⁹) eV = 0.07 eV E=(n+0.5)hf n=(E/hf) - 0.5 = =(1.6•10⁻¹⁹/6.63•10⁻³&#...
November 28, 2013

physics
(a)y(max) = 2k Lλ/2d = k Lλ/d tan φ= k Lλ/L d = k λ/d tan φ₁=1•λ/d tanφ₂=2•λ/d tan φ₂=2•tan φ₁ 2•tan10 φ₂ ≃20⁰ (b) y(min) = (2k+1) Lλ/2d tan φ...
November 28, 2013

Physics
m₀=1.6749•10⁻²⁷kg E=949 MeV=1.52•10⁻¹⁰ J E=mc² = m=E/c² =1.52•10⁻¹⁰/(3•10⁸)²=1.6889•10⁻²⁷kg m=m₀/√(1- β²) (1- β²)=(m₀/m...
November 28, 2013

currerent amd magnetism
I(max) = B•c•r/2 = =0.01•3•10⁸•0.0005/2 = 750 A
November 28, 2013

PHYSICS
U₀=U√2 =210•1.41 = 297 V ω=2πf =2π•90=180π rad/s U=U₀ cos ωt= 297 cos 180πt
November 27, 2013

Physics
a₁=0.8 m/s² v₁=20 m/s a₂=1.2 m/s² v₂=12 m/s bike: the time to rich v₂ is t₂ =v₂/a₂ = 12/1.2 = 10 s. the distance to the meeting point -for bike s= a₂t₂²/2 +v₂(t-t₂) -for bus s=a₁t²...
November 27, 2013

Physical Science
d/ 2 A1 + 3 CuSO4 = 3 Cu + A12 (SO4)3
November 27, 2013

physics
http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/assignments/sol8.pdf
November 27, 2013

Phisics
x=2.2•10⁻² m v=0.65 m/s m=2 kg k =240 N/m => ω=sqrt(k/m) = sqrt(240/2) =11 rad/s x=Asin ωt v= ω Acos ωt tan ωt = xω /v=2.2•10⁻²•11/0.65 =0.372 ωt =20.4° sin ωt=0.349 x=Asin ωt A=x/sin &#...
November 27, 2013

physics
a=F/m v=v(ini)-at km/h -> m/s !!!!
November 26, 2013

physics
The height of pivot point above the plane of rotation is h cosi=h/Li cosf=h/Lf Lf=Li•cosi/cosf
November 26, 2013

Physics Important please
L=0.2 m => R=0.1 m mv²/R=qvB q/m= v/RB = 2.39•10⁵/0.1•0.1 = =2.39•10⁷ C/kg helium ion He+ q/m= 1.6•10⁻¹⁹/(4•1.67•10⁻²⁷+9.1•10⁻³¹) =2.39•10⁷ C/kg
November 26, 2013

physics
x=Asin ωt v=Aωcos ωt a= Aω²sin ωt F=ma=mAω²sin ωt. F(max)=F(fr) F(max)= mA ω² F(fr) =μmg mAω²=μmg μ=A ω²/g=A(2πf)²/g = =5.2•10⁻²(2π•1.86) ²/9.8=0.23
November 26, 2013

physics
k=mg/x=3.6•9.8/0.018 =1960 f=2.9 Hz => ω=2πf=2π•2.9 = 18.22 rad/s ω²=k/M => M=k/ ω²=1960/(18.22)² = 5.9 kg Δm=M-m=5.9 – 3.6 – 2.3 kg
November 26, 2013

physics
T=t/N =2.9/6 = 0.48 s T=2π•sqrt(m/k) = > k=4 π²m/T²= …
November 26, 2013

Physics please HELP
L=0.2 m => R=0.1 m mv²/R=qvB q/m= v/RB = 2.39•10⁵/0.1•0.1 =2.39•10⁷ C/kg helium ion He+ q/m= 1.6•10⁻¹⁹/(4•1.67•10⁻²⁷+9.1•10⁻³¹) =2.39•10⁷ C/kg
November 26, 2013

Physics
http://ocw.mit.edu/courses/physics/8-01t-physics-i-fall-2004/exams/exam03_pract_sol.pdf
November 24, 2013

Physics
(a) F=F(dr) P=Fv=500•23 =11500 N (b) F=F(dr)+mgsinα=500+710•9.8•sin2=500+242.8 =742.8 N P=Fv=742.8•23=17085 N
November 23, 2013

Magnets
mv²/2=qΔφ v=sqrt(2qΔφ/m) = =sqrt(2•2•1.6•10⁻¹⁹•1000/4•1.67•10⁻²⁷) = 3.1•10⁵ m/s mv²/R = qvB R=mv/qB = 4•1.67•10⁻²⁷•3.1•10⁵/2•...
November 23, 2013

electricity
p=IA= Iπr² τ=pBsinφ (sinφ=1) => τ=pB
November 23, 2013

Physics
http://www.csupomona.edu/~skboddeker/131/131hw/ch6h.htm
November 23, 2013

Physics
http://people.physics.tamu.edu/kattawar/solutions%20218h%20exam2%20f11.PDF
November 23, 2013

physics
p=F/A =mg/4A₀ A₀=mg/4F
November 22, 2013

science
N=N₀exp(-ln2•t/T) ln{N/N₀) = -ln2•t/T t= - ln{N/N₀)•T/ln2= = - ln(3.25/26) •713•10⁶/ln2 = = 2.14•10⁹ years
November 22, 2013

electromagnets
ΔPE=Work W=∫τ•dφ=∫pBsinφ•dφ= =∫IABsinφ•dφ=∫Iπr²Bsinφ•dφ= =Iπr²Bcosφ (limits of integral are π/2 and 0)= Iπr²B W=Iπr²B=2•π•0...
November 22, 2013

electricity and magnetism
p=IA= Iπr² τ=pBsinφ (sinφ=1) => τ=pB
November 22, 2013

science
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/mirray.html
November 22, 2013

physics
v=sqrt{v(p)²+v(w)²-2v(p)v(w)cos α}= =sqrt{100²+30²-2•100•30cos45} =81.6 km/h s= vt=81.6•3=244.8 km β= 85° (northeast)
November 21, 2013

physics
v=sqrt{v(p)²+v(w)²-2v(p)v(w)cos α}= =sqrt{100²+30²-2•100•30cos45} =81.6 km/h s= vt=81.6•3=244.8 km β= 85°v (northeast)
November 21, 2013

Physics
1/λ=R(Z-1)²(1/n² - 1/m²) R=1.1•10⁷ m⁻¹ Z=29 n=1 m=∞ 1/λ=R(Z-1)²=1.1•10⁷•28². λ=3.25•10⁻⁹ m.
November 21, 2013

Warren (physics)
Q=Q₁+Q₂+Q₃ = c₁mΔT₁+ λm + c₂mΔT₂= = m(c₁ΔT₁ + λ+c₂ΔT)= =0.0132(2060•11.9+ 335000+4183•30)= =0.0132(24514+335000+125490)= =6402 J
November 20, 2013

Science
B. Vertically through the center of Earth and through each pole.
November 20, 2013

physics
F(x) =Fcosα F(y)=F sinα
November 20, 2013

Physics
ΔQ=ΔU+W ΔU= ΔQ-W=2438-897 =1541 J ΔU=νcΔT=ν(iR/2) ΔT ΔT=2 ΔU/νiR =2•1541/3•3•8.31=41.2 K ΔT= T₂-T₁ T₂=T₁+ΔT=396+41.2=437.2 K
November 20, 2013

Physics
a. g=9.8 m/s² b. Upward: v=v₀-gt v=0 => t=v₀/g =8/9.8 =0.82 s. t(up) =t(down) t(total)=2•0.82=1.64 s. c. v=v₀=8 m/s
November 19, 2013

physics
T=2πsqrt(R³/GM)
November 19, 2013

Physics
mv²/2 =MV²/2 V=v•sqrt(m/M) = =350sqrt(50•10⁻³/80)= =8.75 m/s mv²/2=mgh h= v²/2g=350²/2•9.8 =6250 m
November 19, 2013

Physics
a=v²/2s F=ma
November 19, 2013

Physics
mv²/2=qΔφ v=sqrt(2qΔφ/m) = =sqrt(2•2•1.6•10⁻¹⁹•1000/4•1.67•10⁻²⁷) = 3.1•10⁵ m/s mv²/R = qvB R=mv/qB = 4•1.67•10⁻²⁷•3.1•10⁵/2•...
November 19, 2013

physics
I=P/4πR² = 35.5/4π•917² = 3.36•10⁻⁶W/m² I₀= 10⁻¹² W/m² Sound level (in dB) β=(10dB)log(I/I₀) = =10•log(3.36•10⁻⁶/10⁻¹²) =65.2 dB
November 19, 2013

electromagnets
F=qvBsinα= =1.6•10⁻¹⁹•4•10⁶•0.5•sin60= =2.77•10⁻¹³ N a=F/m=2.77•10⁻¹³/1.67•10⁻²⁷=1.66•10¹⁴ m/s²
November 19, 2013

physics
I=P/4πR² = 35.5/4π•917² = 3.36•10⁻⁶W/m², I₀= 10⁻¹² W/m², Sound level (in dB) β=(10dB)log(I/I₀) = =10•log(3.36•10⁻⁶/10⁻¹²) =65.2 dB
November 19, 2013

Physics
q=k•A•ΔT/Δx=0.8•4•10•(50-30)/0.15 =4267 W Q=qt=4267•12•3600=7.86•10¹¹ J
November 19, 2013

physics
Young’s Modulus E=17•10⁹ N/m² σ=Eε mg/A=E(ΔL/L) ΔL= mgL/AE= 4mgL/ πD²E= =4•12900•9.8•9.4/π•0.42²•17•10⁹= =5•10⁻⁴ m=0.5 mm.
November 19, 2013

physics
http://answers.yahoo.com/question/index?qid=20100103015632AABnYzd
November 19, 2013

physics
http://answers.yahoo.com/question/index?qid=20121115115746AAMELdR
November 19, 2013

Physics
m₁a=- m₁g+T₁ …….(1) - m₂a=T₂- m₂g ……(2) Iε=(T₂-T₁)R => T₂-T₁ = Iε/R=Ia/R² If the wheel is disc I=mR²/2 => T₂-T₁= Iε/R= mR²a/2R²=ma/2 subtract (2...
November 19, 2013

Physics, Chemistry, Science
• The majority of gas used in most SCUBA tanks is compressed air. This air is composed of the same elements everywhere - 21% Oxygen 79% Nitrogen. Advanced SCUBA divers may use an "enhanced" mixture of 32% (up to about 40%) Oxygen with the balance being Nitrogen...
November 18, 2013

Physics
s=at²/2 a=2s/t²=2•0.939/0.6²=5.22 m/s² F=ma=2.2•5.22=11.484 N
November 18, 2013

Physics
s=at²/2 a=2s/t²=2•0.939/0.6²=5.22 m/s² F=ma=2.2•5.22=11.484 N
November 18, 2013

physics
http://answers.yahoo.com/question/index?qid=20090617182342AAVRQWx
November 18, 2013

Physics
to Anton: F=qvB? where q=e v: m mile/s -> m/s B= 5•10⁻⁵ T
November 18, 2013

Physics
X: m₁v₁=m₁u₁cosα+m₂u₂cosβ Y: 0=m₁u₁sinα - m₂u₂cosβ m₁v₁-m₁u₁cosα = m₂u₂cosβ …(1) m₁u₁sinα= m₂u₂cosβ ……...
November 18, 2013

Science (Physics)
on the Earth W= mg=30•10=300 N on the Moon W₁=mg₁=mg/6 = =W/6 =300/6 = 50 N mg=GmM/R² g=G M/R² => M=gR²/G the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², Earth’s radius is R = 6.378•10⁶ ...
November 18, 2013

Physics
s₁=15 m, a=1 m/s²,t₂=15 s s₁=v²/2a v=sqrt(2as₁) v=at₁ t₁=v/a s₂=vt₂ s= s₁+s₂ t=t₁+t₂
November 18, 2013

Physics- torque
sinα=(3.92-0.506)/8.35 =0.409 α =sin⁻¹0.409 = 24.13º F=832•cosα=832•0.913 =759.6 N τ=759.6•3.92=2977.6 N•m
November 18, 2013

Physical Science
(E) 210/82 Pb -> 210/83 Bi + 0/-1 e + y (C) 49.6 grams
November 18, 2013

physics
sinα=(3.92-0.506)/8.35 =0.409 α =sin⁻¹0.409 = 24.13º F=832•cosα=832•0.913 =759.6 N τ=759.6•3.92=2977.6 N•m
November 18, 2013

physics
h=gt²/2 => t=sqrt{2h/g} => t₁=t₂
November 18, 2013

Physics - pendulum
T₁=2π•sqrt{L/g₁} T₂=2π•sqrt{L/g₂} g₂=g₁(T₁/T₂)²
November 18, 2013

Physics - Oscillations
T=2π•sqrt{m/k} T=t/N t/N=2π•sqrt{m/k} (t/2πN)²=m/k k=m(2πN/t)²
November 18, 2013

physics
F=691+89=780 N p=(F/2)/A=F/2A => A=F/2p=780/2•8.4•10⁵=4.6 10⁻⁴m²
November 18, 2013

physics
ρ=m/V =m/πr²h= =15700/π•1.35²•3.94=696 kg/m³
November 18, 2013

physics
I=mr²/2 mgh= mv²/2 +Iω²/2 = =mv²/2 +mr²v²/r²4 = = mv²/2+ mv²/4 =3mv²/4 v=sqrt{4gh/3} => c)both in same time.
November 18, 2013

Physics
5 N 8.5 N 0 N
November 18, 2013

Physics
- a force that makes the net force on an object zero - It is equal in magnitude and opposite in direction - A moving object in equilibrium continues at a constant velocity.
November 18, 2013

Physics
W = ∫F•dx = a•x + (b/2) •x² - (c/3) •x³ x=0.794 m a = 12600 N, b = 8420 N/m, c = 10100 N/m^2,
November 18, 2013

Physics
when the arrow representing the vector would point toward negative x <-- 10.4 km/h <--
November 18, 2013

Physics, Elena Please Help If u can.
I need the figure
November 18, 2013

physics
Son : m, v Father : M, u M=4m mv²/2=3Mu²/2 => mv²/2=3•4mu²/2 => v²=12 u²…..(1) mv²/2= M(u+1.8)²/2 mv²/2= 4m(u+1.8)²/2 v²= 4(u+1.8)² ….(2) Substitute v² from (1) in (2) 12 u²=4(u+1.8)&#...
November 18, 2013

PHYSICS
m₁a=m₁g-T₁ m₂a=T₂ - m₂gsinα Iε=(T₁-T₂)R => T₁-T₂ = Iε/R=Ia/R²=mR²a/2 R²=ma/2 m₁a+ m₂a= m₁g-T₁+ T₂ - =m₁g- m₂gsinα –( T₁-T&#...
November 18, 2013

physics
T=38.2 N, T₁=28.9 N, T₂=17,4 Buoyant force F In the air T = mg …. (1) In the water T₁=mg-F₁ …..(2) In the unknown liquid T₂=mg-F₂ ….. (3) Substitute (1) in (2) and (3) F₁=mg- T₁=T-T₁=38.2-28.9=9.3 N F₂=...
November 17, 2013

Math- urgent
-3 (x-8)+7x=12 -3x+24 +7x=12 4x=-12 x=-3
November 17, 2013

math
12 persons Each has 2 balloons and 3 prizes
November 17, 2013

physics
Max force the man can apply is F= F(fr)= μN=μmg=0.78•93•9.8=710.9 N Max acceleration a=F/M = 710.9/104000=0.0068 m/s²
November 17, 2013

Math- urgent
If x+4•7=-2 then x+28=-2 x=-30 If x+ 4⁷=-2 then x+16384=-2 x=-16386
November 17, 2013

Math
V=75• 135•0.03=303.75 m³= 303750 L t=V/V₀=303750/250=1215 min=20.25 hours
November 17, 2013

PHYSICS HELP
m₁a=m₁g-T₁ m₂a=T₂- F(fr) 0=m₂g-N Iε=(T₁-T₂)R =>T₁-T₂ = Iε/R=Ia/R² N= m₂g, F(fr)=μN=μm₂g m₁a+ m₂a= m₁g-T₁+ T₂- F(fr)= =m₁g- μm₂g &#...
November 17, 2013

science
a) Mg + 2HCl = MgCl₂ + H₂ b) 2K + 2H₂O = 2KOH + H₂ c) 2Li + 2H₂O = 2LiOH + H₂ d) 4Fe + 3O₂ = 2Fe₂O₃
November 17, 2013

physics
http://www.astro.queensu.ca/~tjb/hw/P10706/hw8_old.pdf
November 17, 2013

Density Problem
density ρ=m/V V=4πR³/3 kilometers -> meters!
November 17, 2013

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