Tuesday
September 16, 2014

Posts by elena


Total # Posts: 4,331

physics
The gravitational constant G =6.67•10⁻¹¹ N•m²/kg², h=100000 m m=1040 kg Earth’s mass is M = 5.98•10²⁴kg, Earth’s radius is R = 6.37 •10⁶ m. (a) F =G•m •M/(R+h)² (b) a= G• M/(R+h)²...
April 22, 2013

science
http://en.wikipedia.org/wiki/Thermal_conduction
April 22, 2013

Physics
B=μ₀I/2πb=1.25664•10⁻⁶•1.24/2π•0.436 =5.69•10⁻⁷ T
April 22, 2013

physics
F=qE=eE=1.6•10⁻¹⁹•341•10⁵=5.456•10⁻¹² N
April 22, 2013

Physics
cosα=1, ℇ=ΔΦ/Δt = N•Δ(B•Acosα)/Δt= =N•A•ΔB/Δt, ℇ=I•R, N•A•ΔB/Δt= I•R, I= N•A•ΔB/Δt•R= =347•0.28•2.4/0.31•49 = 15.35 A
April 22, 2013

physics
cosα=1 ℇ=ΔΦ/Δt = N•Δ(B•Acosα)/ Δt= =N•A•ΔB/Δt ℇ=I•R N•A•ΔB/Δt= I•R I= N•A•ΔB/Δt•R= ...
April 22, 2013

PHYSICS!!!!...PLEASE HELP
v=const => mgsinα=F(fr) = μN= μmgcosα sinα= μcosα μ=tanα
April 22, 2013

physics
mgh=kx²/2 x=sqrt(2mgh/k)
April 21, 2013

Science
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving the atom a net positive or negative electrical charge.
April 21, 2013

Physics
The object located between F and 2F => the image will be located beyond the 2F point on the other side of the lens. It is real, inverted and its dimension is larger than the object demension. d₀ - object distance d₁ - image distance f- focal lenth 1/d₀ +1/...
April 21, 2013

Physics *Electrical Scientist* please help me!!!
http://www.tutorvista.com/science/jj-thomson-atomic-theory-0 http://en.wikipedia.org/wiki/Cathode_ray_tube
April 20, 2013

calculus
t=∛x =x^(1/3) => y=3x^5 = 3x^(5/3). dy/dx =3•(5/3)•x^(2/3) = =5 •125^(2/3)=525=125
April 20, 2013

Physics
d₀ - object distance d₁ - image distance f- focal lenth 1/d₀ +1/d₁ =1/f, 1/d₁ =1/f - 1/d₀ = = (d₀-f)/ d₀•f, d₁=d₀•f/(d₀-f)= =0.4•0.15/(0.4-0.15)=0.24 m, 0.03/0.4 =h/ d₁ , h= d₁•0....
April 20, 2013

Physics
mgsinα=F(fr) = μN= μmgcosα sinα= μcosα μ=tanα
April 20, 2013

calculus
s= 189t- t³ v=ds/dt = 189-3t² t=0 = > v=189 m/s. 189-3t² = 0 t=√(189/3) =√63 = 7.94 s. s=189 t- t³= =189(7.94) -7.94³=1000.1 m a=dv/dt =d(189-3t²)/dt= - 6t t=8 => a= - 6•8 = - 48 m/s²
April 20, 2013

physics
I=2mR²/5 ω=2π/T KE= Iω²/2
April 20, 2013

Physics
m₁gh= m₁v₁₀²/2 => v₁₀=sqrt(2gh) m₂gh= m₂v₂₀²/2 => v₂₀ =sqrt(2gh) m₁v₁₀ - m₂v₂₀= - m₁v₁ + m₂v₂ v₁= {-2m₂v₂₀...
April 20, 2013

Physics
C)λ, ν, and 100E
April 20, 2013

calculus (gr 12)
f(x) = 2x³+4x²-5x+8 f′(x) =6x²+8x-5 f′(-2) = 2(-4) ² +8(-2) -5 = 11
April 19, 2013

calculus
f(x) =x⁴-3x f′(x) = 4x³ -3 => f′(3) = 4•3³ -3= 105
April 19, 2013

calculus (gr 12)
s= 189t- t³ v=ds/dt = 189-3t² t=0 = > v=189 m/s. 189-3t² = 0 t=√(189/3) =√63 = 7.94 s. s=189 t- t³= =189(7.94) -7.94³=1000.1 m a=dv/dt =d(189-3t²)/dt= - 6t t=8 => a= - 6•8 = - 48 m/s²
April 19, 2013

physics
X: ma=Fcosα-F(fr) Y: 0=-mg+N+Fsinα =>N=mg-Fsinα F(fr) = μN=μ(mg-Fsinα) ma= Fcosα- μ(mg-Fsinα) a = { Fcosα- μ(mg-Fsinα)}/m
April 19, 2013

physics
S=(v-v₀)•t=(2-1) •3•60= 180 m
April 19, 2013

physics
F₁=k•q₁•q₂/r₁², F₂=k•q₁•q₂/r₂², F₁/F₂=k•q₁•q₂•r₂² / k•q₁•q₂•r₁², F₂= F₁• r₁²/r &#...
April 19, 2013

Physics
T₁=2πsqrt(m₁/k) T₂=2πsqrt(m₂/k) T₁/T₂=sqrt{m₁/m₂} T₂=T₁/sqrt{m₁/m₂}= 2.8 s
April 19, 2013

Physics
λ=v/f =3•10⁸/6•10¹⁶=5•10⁻⁹ m
April 19, 2013

Literature ?! Check my answers?
CCB! just took test too!
April 17, 2013

Physics :)
Angular acceleration= torque/moment of inertia
April 13, 2013

physics
T + mg = mv²/R => T = m (v²/R -g)
April 13, 2013

physics
Tsin(α/2)=kq²/{2Lsin(α/2)}², Tcos(α/2)=mg. tan(α/2)= kq²/mg{2Lsin(α/2)}², m= kq²/g{2Lsin(α/2)}²•tan(α/2)=...
April 13, 2013

physics
m₁gh₁ =mv²/2, v=sqrt(2gh₁)=… m₁v=(m₁+m₂)u, u= m₁v/(m₁+m₂)=.. . (m₁+m₂)u²/2=(m₁+m₂)gh₂, h₂=(m₁+m₂)u²/2(m₁+m₂)=..
April 13, 2013

physics
h=gt²/2 t=sqrt(2h/g) =sqrt(2•200/9.8)=6.39 s
April 12, 2013

Physics
a) density b) acceleration c) - d) - e) refractive index f)capacity g)resistance h) pressure
April 11, 2013

physics
a=F/m=90/(40+3) = 2.1 m/s2
April 11, 2013

physics
ma=F(fr), mv²/R =μmg, v=sqrt(μRg) = sqrt(0.63•39.6•9.8)= …
April 11, 2013

physics
F(x) =-F(1x) +F(2x)+F(3x) – F(4x) = =(G•m₅•cos45°•2/s√2)•(-m₁+m₂+m₃-m₄)=... F(y) = F(1y) +F(2y)-F(3y) – F(4y) = =(G•m₅•sin45°•2/s√2)•( m₁+m₂-m₃-m₄...
April 11, 2013

Physics!! HELP
λ=2•2.5=5 m s=14•5=70 m v=s/t=70/15=4.67 m/s
April 11, 2013

Physics
An object is placed 11 cm in front of a concave mirror whose focal length is 23 cm. The object is 3.6 cm tall. Determine (a) the location of the image, taking a real image as a positive value and a virtual image as a negative value. (b) Determine the height of the image, where...
April 11, 2013

Physics Hear
1) Q=c•m•ΔT=4183•10•(100-20)=3346400 J 2) Q=Lm = 2260000•0.01 = 22600 J 3) Q= Q₁+Q₂+Q₃= c₁•m•ΔT₁+rm+ c₂•m•ΔT₂= =2060•3•7+ 335000•3+4183•3•25 = =43260...
April 11, 2013

physics
http://en.wikipedia.org/wiki/Snell's_law
April 11, 2013

Physics
a=v/t=20/25 = ...
April 11, 2013

physics
Please see the Related Questions below
April 11, 2013

Physics
n=actual depth/apparent depth = =3/(3-1.1) = 3/1.9=1.58
April 10, 2013

physics
P=(m₁+m₂)g/A=(40+12) •9.8/2(6•4)•10⁻⁴=106167 Pa= 106.167 kPa
April 10, 2013

physics
v(ave) =total distance/ time taken = =(210+470+150)/(25+20+30) = 11.7 m/s
April 10, 2013

Physics
n₁ = 1.520 n₂= 1.538 n₁=sini₁/sinr₁ n₂=sini₂/sinr₂ sinr₁=sinr₂ sini₁/n₁=sini₂/n₂ sini₂=n₂•sini₁/n₁=1.538•sin 20.97/1.52 =0.3621 i₂=21.23°
April 10, 2013

physics
p=mv
April 7, 2013

physics
(a) v=at=0.3•15=0.45 m/s (b) v₁=30km/h=30000/3600 =833.3 m/s t₁=v₁/a=833.3/0.3 =2777.8 s. (c) s=v₁²/2a= 833.3²/2•0.3=1157314 m =1157 km
April 7, 2013

physics
F= F(fr) + mgsinα= =32.6 +63.8sin59=87.3 N
April 7, 2013

physics
1T=10000 Gauss B=0.02•10⁻⁴= 2•10⁻⁶ T v=8 km/s=8•10³ m/s U=BLv= 2•10⁻⁶•4828• 8•10³=77.25 V
April 7, 2013

Physics
ℰ=-dΦ/dt=-d(NBAcosωt)/dt= =NBAωsinωt = =500•0.05•0.05•20•sin30° =12.5 V
April 6, 2013

Physics (Algebra-based)
PE → KE1 KE1 → Work(fr) +KE2 => PE → Work(fr) +KE2 If the initial height is ‘h₁’, the height of the horizontal section is ‘h₂’, the length of the rough section is ‘s’, then mg (h₁-h₂)=μmgs +mv²...
April 6, 2013

physics
vt=at²/2 t=2v/a=2•19.4/3.2=121.25 s=2.02 min
April 6, 2013

physics
ℰ=-dΦ/dt=-d( BAcosα )/dt cosα=1 ℰ =BA/t= Bab/t=Bb(a/t)=Bbv= =0.125•0.045•4.3=0.024 V
April 6, 2013

physics
ma=F => a=F/m=2/2.5=0.8 m/s² v=v₀-at v=0 t=v₀/a=0.6/0.8=0.75 s.
April 6, 2013

physics
During acceleration (or deceleration) of the bus, she continues to move in previous derection due to inertia, and, therefore, she may fall down.
April 6, 2013

physics
Energy =Power x time =680 W/m2 x 1 second =680 Joule/m2 Energy of 1 photone = hf =hc/λ Number of photones =Energy/energy of 1 photon = N=680• λ/hc=680•478•10⁻⁹/6.63•10⁻³⁴•3•10⁸=…
April 6, 2013

Physics
(a) Torque is M=p⒨•B•sinα p⒨=NIA If M(max) =sin α=1 M(max)=NIAB, I= M(max)/NAB = =40/250•0.12•0.04•1=33.3 A (b) ℰ=-dΦ=-d(NBAsinωt)/dt= =-NBAωcosωt ℰ(max)=NBAω=2πNBAf= =2π•250&#...
April 6, 2013

physics
(a) I =cε₀E²/2 =3•10⁸•8.85•10⁻¹²•(7.9•10⁻⁶)²/2=8.2•10⁻¹⁴W/m² (b) P=I•A=I•πD²/4=8.2•10⁻¹⁴•π•2.1²/4=2.84•...
April 5, 2013

physics
PE=mgh=10•2=20 J. PE->KE
April 5, 2013

physics
Question????
April 4, 2013

Physics
The speed at the 5-m level is of the same magnitude on the way up and on the way down=> s=(v²-v₀²)/2g Solve for v₀
April 4, 2013

Physics 2
tanα=x/L=3.2•10⁻³/9=3.56•10⁻⁴ tanα≈sinα bsinα=kλ b= kλ/sinα=1•530•10⁻⁹/3.56•10⁻⁴=1.5•10⁻³ m
April 2, 2013

Physics
M=Iε ε=M/I = 22.9/0.168 = 136.3 rad/s² 2πN=2πn₀t + εt²/2 2πn=2πn₀ + εt n₀=0 => 2πN= εt²/2 2πn= εt => t=2πn/ε N= πn²/ε n=sqrt {εN/π}= =sqrt{136....
April 2, 2013

physics
Δp(rocket)=Δp(gas)= mv=26•182=4732 kg•m/s
April 2, 2013

Physics
2s=ct s=ct/2=3•10⁸•2.56/2=3.84•10⁸ m
April 2, 2013

Physics
2s=vt s=vt/2=345•4.4/2=759 m
April 2, 2013

Physics
t=2s/v=2•150/345=0.87 s
April 2, 2013

Physics
Speed of sound at 20⁰ v=343.1 m/s λ=v/f=343.1/512 =0.67 m
April 2, 2013

Physics
M=M(fr) M=p⒨Bsinα sinα=sin90=1, M=NIAB M(fr)=F(fr)R=μF⒩R NIAB =μF⒩R F⒩= NIAB/μR= =425•0.27•3•10⁻³•0.21/0.81•0.011= =8.11 N
April 2, 2013

Physics
λ=v/f Speed of sound at 20⁰ v=343.1 m/s f=v/ λ=343.1/0.667=517.4 Hz
April 2, 2013

machanics
A vertical distance covered for t₁=10 s of accelerated motion is h₁=at₁²/2. The speed at this height is v₁=at₁. The distance covered at decelerated motion during t₂=15- t₁=15-10=5 s is h₂=v₁t₂-gt₂²/2. ...
April 2, 2013

physics
h=at²/2 a=2h/t²=2•0.76/5.2²=0.056 m/s² Two equations for the loads -m₁a=m₁g-T₁ => T₁=m₁(g+a) ….(1) m₂a=m₂g-T₂,=> T₂=m₂ (g+a) ….(2) and the 3rd equation (on the base of Newton&#...
April 2, 2013

physics
See the Related Questions below.
April 2, 2013

physics...
v=sqrt(v₁²+v₂²) = sqrt(4+1) =2.236 m/s s=vt=2.236•5=11.18 m
April 2, 2013

PHYSIcs!!!
h=gt²/2=> t=sqrt(2h/g). s=vt=> v=s/t=s/ sqrt(2h/g)= =20/sqrt(2•2/9.8)=31.3 m/s
April 2, 2013

simple PHYISCS
h=gt²/2 t=sqrt(2•5/g)=1.01 s
April 2, 2013

physics
N= mgcosα F(fr)=μN (a) T₁= mgsinα -F(fr) = = mgsinα - μ(s)mgcosα (b) T₂=F(fr) +mgsinα= =μ(s)mgcosα +mgsinα (c) T₃=F(fr) +mgsinα= =μ(k)mgcosα +mgsinα
April 2, 2013

Physics
R₂= 116 Ω, ℰ=120 V, P₁=20.7 W, The resistance of light buble R₁=? R=R₁+R₂, I=V/R, R₁=P₁/I²=P₁R²/V²=P₁(R₁+R₂)²/V². R₁²+(2R₂ - V²/P₁)R₁+R₂...
April 1, 2013

Physics
80•110•10⁶•5.9 =5.192•10¹⁰ W=5.192•10⁷ kWh, 5.192•10⁷•0.11=5.71•10⁶ dollars
April 1, 2013

Physics
ℰ=IR=IρL/A => I₁ρL₁A = I₂ρL₂A L₂=I₁L₁/I₂=2.3•52/2.9=41.2 m
April 1, 2013

Physics
R=4.9•10⁹ Ω V=68•10⁻³V I=V/R=68•10⁻³/4.9•10⁹=1.39•10⁻¹¹ A I=q/t =Ne/t N=It/e=1.39•10⁻¹¹•0.45/1.6•10⁻¹⁹=3.9•10⁷
April 1, 2013

Physics
http://basketball.lifetips.com/cat/59049/vertical-jump/index.html Ans. b
April 1, 2013

Physics
M=F(fr)•(d/2) =μ•F•(d/2)= 0.15•0.62•1.2•10⁻²/2 =0.000558 N•m
April 1, 2013

Physics
(a)KE=mv²/2 (b) PE=mgh (c) KE1=KE+PE (d) mv₁²/2= mv²/2+mgh v₁= sqrt(v² +2gh)
April 1, 2013

CHM 1010
p₁V₁=p₂V₂ p₂=p₁V₁/V₂
April 1, 2013

Physics-friction problem
ma=F(fr) =μN=μmg a= μg. s=(v₀²-v²)/2a= =(v₀²-v²)/2μg => v=sqrt{v₀²-2μgs}= =sqrt{21.2²-2•0.005•9.8•58.5} = =21.06 m/s. For the 2nd case: s=(v₀²-v²)/2μ₁g= =(21.2...
April 1, 2013

physics
h=v₀t+gt²/2, gt²+2v₀t-2h=0 Solve for t. v= v₀+gt
April 1, 2013

Physics - Electric Potential
ΔPE= -Work=-qΔφ= -{(-0.15)•(13-60)} = =-7.05 J
April 1, 2013

Physics
F=ILBsinα B=F/ILsinα=0.15/67•45•sin51.5⁰=6.35•10⁻⁵ T
April 1, 2013

PHYSICS
Work =500mgh=500•12•9.8•2=117600 J. You need 117600•100/20 =588000 J 1 kg gives 30•10⁶J, mass of burning fat is 588000/30•10⁶ = 0.0196 kg
April 1, 2013

Physics
h=at²/2=20•16/2=160 m
April 1, 2013

Physics
(a) (m₁+m₂)v=m₁v₁+m₂v₂ v₁(a)= {(m₁+m₂)v-m₂v₂}/m₁ (b) (m₁+m₂)v=m₁v₁-m₂v₂ v₁(b)= {(m₁+m₂)v+m₂v₂}/m₁ (c) (m₁+m₂)v=m₁v...
April 1, 2013

physics
L=2mvx=2•m•v•(b/2)=2•3•5.41•3.15/2= ...
April 1, 2013

physics
m₁=m= 70 kg m₃=0.175 kg, v₃=10 m/s Let v₃ be positive and directed to the right 0= - m₁v₁+m₃v₃ v₁=m₃v₃/m₁=0.175•10/70=0.025 m/s (directed to the left) m₃v₃ =(m₂+m₃)v v= m₃...
April 1, 2013

physics
Q1=Q2+cm•Δt c=(Q1-Q2)/ m•Δt= =(12000-1300)/0.185•(73-22)= =1134 J/kg•℃
April 1, 2013

Physics
F=qvB sin12⁰ 1.8F=qvBsinφ sinφ/sin12⁰ =1.8 sinφ =sin12⁰•1.8=0.208•1.8=0.374 φ=sin⁻¹0.374=22⁰
April 1, 2013

PHYSICS help please!!!!!!!!!!
Q(gained) =Q(lost) Q(lost) =Q₁+Q₂+Q₃ Q₁ = c₁m(Δt₁)=2020•1•(120-100) = 40400 J Q₂ = Lm=2256000•1= 2256000 J Q₃=c₂m(Δt₂)=4186•1•(100-85) = 62790 J Q(lost) =40400 +2256000+62790 =...
March 31, 2013

PHYSICS help please!!!!!!!!!!
Q(gained) =Q(lost) Q(gained) =Q₁+Q₂+Q₃ Q₁ = c₁m(Δt₁)=2020•1•(120-100) = 40400 J Q₂ = Lm=2256000•1= 2256000 J Q₃=c₂m(Δt₂)=4186•1•(100-85) = 62790 J Q(gained) =40400 +2256000+62790 =...
March 31, 2013

physics
After the 1st rebounce the speed is v/2, after the 2nd rebounce – v/4, after the third rebounce –v/8, => m(v/8)²/2=mgh₁ v=sqrt(128gh₁) =141.7 m/s mv²/2=mgh h= v²/2g=141.7²/2•9.8=1024 m
March 31, 2013

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