Friday
December 19, 2014

Posts by elena


Total # Posts: 4,338

physics Important please
R₀=8 Ω, T₀=20℃, R₁=8.4 Ω, T₁=70℃, T₂ = - 10℃ R₂=? R=R₀[1-αΔT] R₁=R₀[1-αΔT₁] 8.4=8[1+(70-20)α] α={8.4/8 – 1)/50 = 10⁻³ K⁻¹ R₂=R...
November 12, 2013

physics Important please
q=It=Ut/R
November 12, 2013

Phyics
W=mg=ρVg= ρπr²hg= =2.2•10³•π•0.55²•1.9•9.8 = =38929 N=173173 lb
November 12, 2013

phyics
F₁=kx₁ F₂=kx₂ F₁/F₂=x₁/x₂ F₂=F₁x₂/x₁
November 12, 2013

physics
KE=W(resistive force) mv²/2 = Fs F= mv²/2s
November 12, 2013

physics
mv²/R =mg v=sqrt(gR)
November 11, 2013

Physics
do=15.1 cm, R=8.55 cm, H= 6.7 cm di= ? h=? 1/do – 1/di = -2/R 1/di = 1/do+2/R = 1/15.1 +2/8.55. di= 3.33 cm The virtual image is smaller and closer to the mirror than the object h/di =H/do => h=H•di/do = 6.7•3.33/15.1 =1.48 cm
November 11, 2013

Physics please HELP
KE=Iω²/2 =I•4π²/2T² T=2 π•sqrt{I/2•KE} If KE↓ => T↑
November 11, 2013

physics
C=ε₀A/d C=q/U=> q=CU = ε₀AU/d E=σ/2ε₀ =q/A•2ε₀= = ε₀AU/d•A•2ε₀=U/d The same result may be obtained from E=-gradΔU => E=ΔU/Δx =U/d
November 11, 2013

Physics please HELP
KE=Iω²/2 =I•4π²/2T² T=2 π•sqrt{I/2•KE} If KE↓ => T↑
November 11, 2013

physics
Energy = PE = PE₁₂+PE₁₃+PE₁₄+PE₂₃+PE₂₄+PE₃₄= =kq₁q₂/a +kq₁q₃/a+kq₁q₄/a+ kq₂q₃/a+kq₂q₄/a +kq₃q₄/a . Since q₁=q₂=q₃=q...
November 11, 2013

PHYSICS(HELP)
Prob # 7 ocw.mit.edu/courses/physics/8-01sc-physics-i-classical-mechanics-fall-2010/two-dimensional-rotational-motion/two-dimensional-rotational-dynamics/MIT8_01SC_problems21_soln.pdf
November 11, 2013

physics
F=ma=mΔv/Δt=m[v₂-v₁]/Δt= =0.38•[-1.9-2.3]/3•10⁻³ = - 532 N ( direction: from the wall)
November 11, 2013

Physics falling ladder
http://www.mathematische-basteleien.de/ladder.htm
November 11, 2013

physics
a=v²/2s
November 11, 2013

Phyics
T=2π•sqrt(L/g) L=T²g/4π² = =8.36²•9.8/4π²=17.35 m
November 11, 2013

physics
q₁ = 3 e, q₂ = 12e, q₃ = 5e The electric field at the midpoint is E= kq₂/(x/2)²- kq₁/(x/2)²= =k(12e-3e)/(x/2)² =k36e/x² (directed to the 3e charge) F= q₃E=k36e•5e/x²= =k•180e/x², where k =9•10&#...
November 11, 2013

physics
q₁ = 3 e, q₂ = 12e, q₃ = 5e The electric field at the midpoint is E= kq₂/(x/2)²- kq₁/(x/2)²= =k(12e-3e)/(x/2)² =k36e/x² (directed to the 3e charge) F= q₃E=k36e•5e/x²= =k•180e/x², where k =9•10&#...
November 10, 2013

physics
q₁ = 3 e, q₂ = 12e, q₃ = 5e The electric field at the midpoint is E= kq₂/(x/2)²- kq₁/(x/2)²= =k(12e-3e)/(x/2)² =k36e/x² (directed to the 3e charge) F= q₃E=k36e•5e/x²= =k•180e/x², where k =9•10&#...
November 10, 2013

Physics Part 2
m₁=m₂=m=0.17 kg, α=45° v=5.6 m/s, v₁=3.5 m/s, v₂=? vector p =vector p₁+vector p₂ p₂=sqrt{p₁²+p²-2p₁•p•cosα} = =m•sqrt{3.5²+5.6²-2•3.5•5.6•cos45°} = =m•...
November 10, 2013

PHYSICS (HELP)
R=2 m, Ic=9000 kg•m², r₀=1.2 m, m=20 kg, F=200 N, Δt=18 s. I=Ic+2I₀=Ic+2m r₀² = =9000+2•20•1.2²=9057.6 kg•m². M=Iα α=M/I=FR/I =200•2/9057.6 = 0.044 rad/s² ω=α•Δt =0.044•...
November 9, 2013

additional science: physics
m=F/g=1.94/9.7=0.2 kg g=GmM/(R+H)² g₀=GmM/R² =9.8 m/s²
November 9, 2013

physics
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², F =G•m₁•m₂/R²= G•m² /R² F/W=F/mg = G•m² /R²mg = G•m /R²g. mg= G•m•M/R²=> g= G•M/R² . F/W= G&#...
November 9, 2013

Physics
Distance between charges is d=sqrt{3²+3²} =4.24 cm x=d/2 =4.24/2 =2.12 cm =0.0212 m E=kq₁/x²-kq₂/x² = =k12e/x²-k3e/x²=k9e/x²= =9•10⁹•9•1.6•10⁻¹⁹/0.0212²= =2.9•10⁻⁵ N/C
November 8, 2013

Physics ASAP PLease
ΔV =V(∞)-V V(∞)=0 V=0 => ΔV = 0 Work of electric field = q₃ΔV=0 Answ. c)
November 8, 2013

Physics
KE₂-KE₁=Fs F= (KE₂-KE₁)/s=(10-8)/6 = 0.33 N
November 8, 2013

Physics
KE=W =Fs =0.8•0.5 = 0.4 J
November 8, 2013

Physics
W=mg=1768•9.8 = …N
November 8, 2013

Physics
KE=mv²/2
November 8, 2013

Physics Important please
E=kq₁/x²=kq₂/(3-x)² 3e/x²=12e/(3-x)² 9-6x+x²=4x² 3x²+6x-9=0 x²+2x-3=0 x=1 cm
November 8, 2013

Physics
KE=W(fr) mv₀²/2=F(fr)s=μmgs s= v₀²/2μg v=v₀-at v=0 => a= v₀/t s=v₀t-at²/2= = v₀t- v₀t²/2t= v₀t/2 t=2s/v₀=2v₀²/2μgv₀= =v₀/μg=6/0.1•9.8 =6.12 s
November 8, 2013

PHYSICS
KE=PE mv₀²/2=mgh=mgs/sinα s= v₀²sinα /2g= =5.5²sin23°/2•9.8 =… v=v₀-at v=0 => a= v₀/t s=v₀t-at²/2= = v₀t- v₀t²/2t= v₀t/2 t=2s/v₀=….
November 8, 2013

Physics
ΔV =V(∞)-V V(∞)=0 V=0 => ΔV = 0 Work of electric field = q₃ΔV=0 Answ. c)
November 8, 2013

PHYSICS
(a) The equations of the motion: - of the cylinder Iε =M Ia/R =TR T= Ia/R² - of the object m₂a=m₂g-T m₂a=m₂g- Ia/R² a(m₂+ I/R²) =m₂g a= m₂g/ (m₂+ I/R²) (b) T= Ia/R²=Im₂g/ R² (m₂+ I/...
November 8, 2013

phy
1/do+1/di=1/f 1/di= 1/0.21 – 1/1 = 3.76 di=0.26 m D=di+do =0.26+1 = 1.26 m (b) 1/do+1/di=1/f di =f•do/(do-f) D=do+di = =do+ f•do/(do-f) =do²/(do-f) For finding D(min) let differentiate D(do) D´={do²/(do-f)}´={2•do(do-f) -do²(1-f)}/(...
November 8, 2013

physics
Vector sum of two vectors at right angles p=sqrt{p₁²+p₂²} =sqrt2 =1.41 kg•m/s
November 8, 2013

Physics Classical Mechanics
Problem 7.9 http://ocw.mit.edu/courses/physics/8-01-physics-i-classical-mechanics-fall-1999/assignments/sol7.pdf
November 7, 2013

Science
http://www.lenntech.com/periodic/elements/as.htm http://en.wikipedia.org/wiki/Arsenic
November 6, 2013

Science
- The age of a solid object - to measure absolute time - measure how long it takes for unstable nuclei to turn to more stable nuclei
November 6, 2013

physics
η = W/Q =1- (T(cold)/T(hot)) W= ηQ =0.67•5900 =3953 J
November 6, 2013

PHYSICS
http://phys.thu.edu.tw/~ycchen/physics/ebook-8.01x/chapter24_physical_pendulum_v03.pdf
November 6, 2013

Physics ASAP PLease
http://www.univsul.org/Dosekan_Wanekan_D/Third%20Examination%20and%20its%20Solutions.pdf
November 6, 2013

physics
http://www.physicsclassroom.com/class/circles/u6l3d.cfm
November 6, 2013

physical
F₀cosα=ma₀ (x) a₀ (x) =F₀ cosα/m=200•0.707/3.9 =36.3 m/s² F₀ sinα =ma₀ (y) a₀ (y) = F₀ sinα/m=200•0.707/3.9 =36.3 m/s² a(y)= a₀ (y)-g =36.3-9.8 =26.5 m/s² a=sqrt(a₀ (x)&#...
November 5, 2013

Physics
d=sqrt(s₁²+s₂²) = sqrt(49+100) =12.2 km
November 5, 2013

phyics
(a)W=kx k=W/x=829/0.538 = 1540.9 N/m (b)W₁=kx₁=1540.9•0.390 =600 N
November 5, 2013

Math Help? Check my answers.
1. r/5 = 9/21 r = 9 r = 2.14 r = 11.66 r = 37.8 2. A recipe calls for 3 cups of flour to make 3 dozen cookies. Use the proportion to calculate how much flour is needed to make 9 dozen cookies. 3cups/3dozen = xcups/9dozen 6 cups 3.5 cups 9 cups 12 cups 3. Chase sold 48 tickets ...
November 5, 2013

physics
h= v₀t + gt²/2 gt²+2v₀t-2•h = 0 9.8t²+2•10t- 2000=0 t=[20±sqrt{400+4•9.8•1000}]/2•9.8 = =(20±199)/19.6 => t=11.2 s.
November 5, 2013

physics
m₁=2.4 kg, m₂=1.4 kg, v₁=4.6 m/s, v₂=0 m₁v₁= (m₁+m₂) u u= m₁v₁/(m₁+m₂) =2.4•4.6/(2.4+1.4) =2.9 m/s At the edge of the table, two boxes have kinetic (KE) and potential energy (PE), and near the ground...
November 5, 2013

physics
I₁=6A, I₂=8 A, b=0.14 m. (a) B₁=μ₀I₁/2πb=4π•10⁻⁷•6/2π•0.14=8.57•10⁻⁶ T (b) F₂ =I₂B₁Lsinα α=90° =>sinα=1 F₂/L =I₂B₁= =μ&#...
November 5, 2013

PHYSICS
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/toroid.html
November 5, 2013

PHYSICS
B₁= μ₀NI/2πr = 4π•10⁻⁷•800•12000/2π•0.7= … B₂= μ₀NI/2πR = 4π•10⁻⁷•800•12000/2π•1.3= …
November 5, 2013

Physics - PLEASE HELP
245 N
November 4, 2013

Physics
http://answers.yahoo.com/question/index?qid=20091116155804AA13w8n
November 4, 2013

Physics
conservation of angular momentum L₁=L₂ I₁ω₁=I₂ω₂ I₁/I₂=ω₂/ω₁
November 4, 2013

physics
t=(v-v₀)/a =(9.6-5.6)/0.65 = 6.15 s
November 3, 2013

physics
τ =m₁gL₁cosα +m₂gL₂cosα = = gcosα(m₁L₁ +m₂L₂) = =9.8•cos33°(51•1.4+26•2.1) = =9.8•0.84•(71.4+54.6)=1037.232 N•m
November 3, 2013

Physics
v(rain) = v(car)/ tanα
November 2, 2013

Physics
L=v(x)t t=L/v(x) =25/15=1.67 s h=gt²/2=9.8•1.67²/2=13.6 m
November 2, 2013

PHYSICS
F=qvBsinα sinα=1 q=e=1.6•10⁻¹⁹ C F=evB B↓v←F⊙ mv²/R=evB R=mv/eB
November 1, 2013

PHYSICS
B=0.014 T KE=670 eV =1.6•10⁻¹⁹•670 =1.072•10⁻¹⁶ J KE=mv²/2 v=sqrt{2•KE/m} = 2•1.072•10⁻¹⁶/9.1•10⁻³¹=1.5•10⁻⁷ m/s F(el) = F(mag) eE =evB E=vB =1.5•10...
November 1, 2013

physics
m₁v₁+m₂v₂=(m₁+m₂)u u= {m₁v₁+m₂v₂}/(m₁+m₂)
October 31, 2013

Physics
mgh=mv²/2 v=sqrt{2gh}=23.7 m/s
October 31, 2013

physics
http://answers.yahoo.com/question/index?qid=20131024125117AAJx0z3
October 31, 2013

physics
1) v=0 2) v(y) = 0 => v=v(x)=141 m/s
October 31, 2013

physics
a=F/m v=at=Ft/m => t=mv/F
October 31, 2013

physicsh
a=F/m v=at=Ft/m => t=mv/F
October 31, 2013

physics
http://answers.yahoo.com/question/index?qid=20130331123903AAHF36J
October 30, 2013

Physics
mgsinα=μ mgcosα tanα=μ α=arctan0.45 =24.2°
October 30, 2013

physics
Let a material point of mass m is at a distance r from the center of the Earth. If r >R (the Earth's radius), then F = GmM / r ² where G - gravitational constant , and M - the mass of the Earth. If r <R, then the Earth’s action exerted on the point can be ...
October 30, 2013

Physics
F=ma
October 30, 2013

Physics
b) Ff c) m
October 30, 2013

Physics
F=ma=mv²/R
October 29, 2013

PHYSICS
KE=mv²/2 => v=sqrt(2KE/m) = =sqrt(2•11•10⁶•1.6•10⁻¹⁹/1.67•10⁻²⁷)=4.6•10⁷ m/s F=qvBsinα sinα=1 q=e F=ma=mv²/R =evB B=mv/eR = =1.67•10⁻²⁷•4.6•10&#...
October 29, 2013

physics
U =U₀exp(-t/RC) U/U₀ =exp(-t/RC) ln(U/U₀) = -t/RC t= - RC ln(U/U₀) = = - 1•10⁶•2•10⁻⁶•ln(0.75•6/6)=0.58 s
October 29, 2013

physics
Time constant T=RC U =U₀exp(-t/RC) U/U₀ =exp(-t/RC) U₀/2U₀ =1/2 = exp(-t/RC) ln(1/2) = -t/RC) ln(1/2) =- ln2 ln2 = t/RC t=RC•ln2=T•ln2
October 29, 2013

science
a=v²/2s
October 29, 2013

physics
U =U₀exp(-t/T) U/U₀ =exp(-t/T) ln(U/U₀) = -t/T ln(0.01U₀/U₀) =ln0.01 = -t/T t=-Tln0.01=4.61 T
October 29, 2013

physics
U₀ is the max charge of capacitor. Discharging U=U₀exp(-t/T)= =U₀exp(-2T/T)= =U₀exp(-2)=0.135U₀ Charging U=U₀{1-exp(-t/T)}= = U₀{1-exp(-2)}= U₀(1-0.135)=0.865U₀
October 29, 2013

physics
http://faculty.wwu.edu/vawter/PhysicsNet/Topics/DC-Current/RCSeries.html
October 29, 2013

physics
σ =Eε σ=Weight/A σ₁ =mg/πr²= E₁ε σ₂=Mg/πR² =E₂ε (mg/πr²):(Mg/πR²) = (E₁ε):( E₂ε) R =sqrt[ r²•M•E₁/m•E₂]=….
October 29, 2013

physics
KE(total)= KE(transl) +KE(rot) = =mv²/2 +Iω²/2= =mv²/2 +(mR²)v²/2R²=mv² v= sqrt{KE/m)=sqrt(0.2/0.04) =0.5 m/s
October 29, 2013

ET3034TUx Solar Energy
a) The majority of silicon crystals grown for device production are produced by the Czochralski process, (CZ-Si) since it is the cheapest method available and it is capable of producing large size crystals http://en.wikipedia.org/wiki/Silicon
October 29, 2013

PHYSICS
F=qvBsinα sinα=1 q=e=1.6•10⁻¹⁹ C F=evB=..... B↓v←F⊙ mv²/R=evB R=mv/eB=.....
October 29, 2013

PHYSICS
ma=qvBsinα sinα=1 q=e ma=evB B=ma/ev = =1.67•10⁻²⁷•2 •10¹³/1.6•10⁻¹⁹•1.2•10⁷= =0.0173 T F=q[v,B] => B is in –y direction
October 29, 2013

physics
B=0.014 T KE=670 eV =1.6•10⁻¹⁹•670 =1.072•10⁻¹⁶ J KE=mv²/2 v=sqrt{2•KE/m} = 2•1.072•10⁻¹⁶/9.1•10⁻³¹=1.5•10⁻⁷ m/s F(el) = F(mag) eE =evB E=vB =1.5•10...
October 29, 2013

Physics 101
L=I ω= (mr²/2) •2πf= mr²πf =59•0.15²• π•2.9=12.1 kg•m²/s
October 28, 2013

physics
m=6173 kg h=4.71•10⁵ m R=4.31•10⁶m T=1.6 h=1.6•3600=5760 s mg=? F=GmM/(R+h)² F=mv²/(R+H) GmM/(R+h)² =mv²/(R+H) G M/(R+h)² = v²/(R+H) G M/(R+h)= v² T=2π(R+h)/v => v=2π(R+h)/T => v²=4 π²...
October 28, 2013

physics
F=ma=mv²/R m=FR/ v²=…..
October 28, 2013

physics
a₁= ω²R₁ a₂=ω²R₂ a₁/a₂ = R₁/R₂ a₂=a₁R₂/R₁= =282•0.0636/0.0316 =567.6 m/s²
October 28, 2013

physics
a=v²/R
October 28, 2013

Physics
v=v₀ +at a=(v-v₀)/t=(32.8-13.5)/11 =1.75 m/s² F=ma=1532.6•1.75 =2682.05 N
October 28, 2013

Physics
V= 6.3m³= A•h =1m•1m• 6.3 m t=h/c=6.3/3•10⁸=2.1•10⁻⁸s. Energy hitting the base of 1m² is E₀=I/A=1.2•10³(W/m²)/1(m²)= = 1.2•10³ W = 1.2•10³ W J/s. E=E₀•t=1.2•10&#...
October 28, 2013

physics
P=F/A =mg/4A₀ A₀=mg/4F = 1660•9.8/4•2.1•10⁵= =1.94•10⁻² m²
October 28, 2013

PHYSICS (HELP)
http://web.mit.edu/8.01t/www/materials/InClass/IC_Sol_W05D1-2.pdf
October 28, 2013

Physics
W(alc) =W(air)-F(buoyant) = W(air)-ρVg V={W(air)-W(alc)}/ρg= ={275-160}/0.7•9.8 =16.8 m³ W(air) =mg =ρ₀Vg ρ₀=W(air)/ Vg = 275/16.8•9.8 =1.67 kg/m³
October 28, 2013

physics(elena)
Problem 3 http://mikebloxham.com/H7A/HW7soln.pdf
October 28, 2013

physics
h=gt²/2 =>t=sqrt(2h/g) L=v(x)•t
October 28, 2013

electricity magnetism physics
ΔKE=W(electric field) =e•Δφ=e•E•x= =1.6•10⁻¹⁹•850•2.5 =3.4•10⁻¹⁶ J.
October 28, 2013

Physics Classical Mechanics
www.google.com.ua/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&ved=0CHAQFjAH&url=http%3A%2F%2Fweb.mit.edu%2F8.01t%2Fwww%2Fmaterials%2FProblemSolving%2FRaw%2Fsolution06.doc&ei=bphuUsyCEsejtAa31YHIDg&usg=AFQjCNF2N0eF8Wa-JIZTeUxi8Etaz_Z5dQ&sig2=ZWISf9N_URhkDrvW1b4cqw&bvm=bv....
October 28, 2013

Pages: <<Prev | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | Next>>

Search
Members