# Posts by Elena

Total # Posts: 4,389

science (physics)
Weight = mg m=Weight/g=3920/9.8=... (kg)

science (physics)
acceleration due to gravity g= 9.8 m/s^2

Physics
q=2.1μC=2.1•10⁻⁶ C, the side of square ia “a” . The potential at the empty corner due to two charges φ=φ₁+φ₂ = kq/a + kq/a= 2kq/a The potential at the empty corner due to three charges φ`=φ₁+φ&#...

Physics
mg=17.1 N => mg= kx k=mg/x On the moon mg`=kx₁ x₁=mg`/k =m•1.6•g•x /mg=1.6x=1.6•0.044=0.0704 m

Physics
q=2.1μC=2.1•10⁻⁶ C, the side of square ia “a” . The potential at the empty corner due to two charges φ=φ₁+φ₂ = kq/a + kq/a= 2kq/a The potential at the empty corner due to three charges φ`=φ₁+φ&#...

Physics
I=const R=R1+R2+R3 +....=

science
Use Newton's 3 law: You can get back to your station if you throw your reaction jet away

Physics
R1=R(AD)+R(DC)=4+4= 8Ω R2=R(AB)+R(BC)= 4+4= 8Ω 1/R =1/R1 +1/R2= 1/8 + 1/8= 2/8= 1/4 R= 4 Ω

physics
Average speed =distance/time= (150+150)/120 =2.5 m/s Average velocity= displacement/time= 0

Physics
I=U/(R1+R2) =2.4/(12+8) =1.2 A, U1= I•R1= 1.2•8 = 9.6 V, U2= I •R2=1.2•12=14.4 V.

Physics
W=ΔKE= mv²/2 =0.02•150²/2=…

Physics
http://www.citycollegiate.com/wave_soundXc.htm

Physics
this is the inertial motion

physics
T(K) =t℃ +273

Physics
d sinθ = 4λ

y=gt²/2 =9.8•0.19²/2 =4.9•0.19² = … For finding the distance you need v(x) s=v(x)• t

Physics
The period is T= 2π•sqrt(m/k) = =2•3.14•sqrt(0.22/12) =0.85 s. It doesn’t depend on „x“

science
mv²/2 =mgh h= v²/2g

physics
I believe that m= 5.1 X 10^- 3 kg F(electr) + F(spr) = mg, qE + k•ΔL=mg E=( mg- k•ΔL)/q= ={5.1•10⁻³•9.8 – 2.4(0.074-0.059)}/6.6 =… V/m

Physics
L(dB) = 10 log₁₀(P₁/P₀)= 10 log₁₀100000= =10•5=50

Physics
T=30/50 = 0.6 s. v=s/t= 0.5/15 = 0.033 m/s λ=vT=0.033•0.6= 0.02 m

physics Electricity
(a) F=k•q₁•q₂/r²=.... k =9•10⁹ N•m²/C² attraction (b) the law of conservation of charge: q(total) = -20+50 = 30 μC The charge on each sphere is q=15 μC F =k•q²/r² = … repulsion

Physics
T₁ =27+273=300 K p₁V₁/T₁= p₂V₂/T₂ T₂ = T₁•p₂V₂/p₁V₁= …. K (!)

Physics
v(n) = ℏn/m•r = e²/4•π•ε₀•ℏ•n= =v₁/n=2.19•10⁶/n m/s n=1 v₁=2.19•10⁶ m/s

physics
mv²/2=k•q₁q₂/r r = 2k•q₁q₂/mv², where k =9•10⁹ N•m²/C² e =1.6•10⁻¹⁹ C. q₁=2e, q₂=79e m=6.64•10⁻²⁷ kg v=2.6•10⁶ m/s

Physics
p1V1 =p2V2 V2=p1V1/p2 d. 0.25 m^3

Physics
v(x0) =v(x)=8 m/s v(y0) =0 v(y)=gt=10•3.8=38 m/s v=sqrt{v(x)² +v(y)²} = =sqrt (8²+38²) = 38.8 m/s

Physics
F(net) = F-F(res) =(2.06-1.75)•10³=0.31•10³=310 N a=F(net)/m= 310/1300=0.24 m/s² s=at²/2=… v=at = …

Physics
W=q•Δφ q= W/Δφ=4.5•10⁻⁴/(300-150)= 3•10⁻⁶C Since this motion takes energy q= - 3•10⁻⁶C

physical
v=ωR=2.08•0.25 =… (m/s)

Science
http://www.currentresults.com/Weather-Extremes/US/hottest-cities-winter.php

Physics
m₁g=kx k= m₁g/x ω=sqrt(k/m₂)=… (rad/s) f=ω/2π=…(Hz)

Physics
speed is the magnitude of velocity speed ===scalar velocity === vector

physical sciences
when the angle between them is zero

science
STP =standard temperature and pressure: T= 273.15 K p=10⁵Pa μ for hydrogen =2 g/mol= 0.002 kg/mol R=8.31 J/mol•K. m=1g=0.001 kg From pV=mRT/μ V= mRT/μp

Physics
93 km/h=93000/3600=25.8 m/s Centripetal acceleration is a=v²/R=25.8²/1350 =0.49 m/s² The average acceleration = =Δv/Δt = (v₂-v₁)/Δt Since velocity is vector, vecor Δv can be found as vector difference (taking into account that ...

Physics
F =G•m₁•m₂/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², Solve for R

Physics
F =G•m₁•m₂/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², m₁ =10.7 kg Sove for m₂

Physics
Earth’s mass is M = 5.97•10²⁴kg, G =6.67•10⁻¹¹ N•m²/kg², R=5 • 6.378•10⁶ = .. (a) mv²/R = G•m •M/R² v=sqrt{ G •M/R) = … (b) T=s/v =3πR/v

Physics
mg = G•m •M/R² where R = 6.378•10⁶ m, 100%=12.89% =87.11%. mg₁ =0.8711mg => G•m •M/(R+h)² = 0.8711 G•m •M/R² 0.8711(R+h)² = R² 0.8711 (R² +2Rh+h²) = R² Solve for h

Physics
kq₁/x²=kq₂/(6-x)² 2/x²=6/(6-x)² 36-12x+x²=3x² 2x²+12x-36=0 x²+6x-18=0 x = - 3±sqrt(9+18) = = - 3 ± 5.2 If q₁ >0 and q₂>0 x= 2.2 cm (to the right from the left charge (between the charges)) If q...

Science
PE->KE mgh=mv²/2 v=sqrt(2gh)

physics
C=q/U q= CU

physics
A=4πr² => r=A/4π φ=kq/r k =9•10⁹ N•m²/C² φ=516 V, A= 1.01 m^2 q= φr/k=φA/4πk=..

Physics
A•B= |A||B| cosα cosα =A•B/ |A||B|= =16/5•5=0.64 α=cos⁻¹α=50.2°

neutral atom q=0; if you remove 2 electrons: q= +2•1.6•10⁻¹⁹= +3.2•10⁻¹⁹ C if you add to electrons: q= - 2•1.6•10⁻¹⁹= - 3.2•10⁻¹⁹ C

q₁ = q₂ = 2•e⁻ =- 3.2 •10⁻¹⁹ C k =9•10⁹ N•m²/C² F=k•q₁•q₂/r² = ... repulsive

Physics
1/R = 1/2.5 +1/3.5 +1/4 = =0.4+0.2857 +0.25 =0.9357 R=1/0.9357 =1.069 Ohm

Physics
1.3 atm =131722.5 Pa p=F/A=4F/πd². d=sqrt(4F/πp)=...

thermal physic
T=273+37=310 K KE=3νRT/2 =3•1•8.31•310/2 =3864 J

Physics
q= 16 μC = 16•10⁻ ⁶ C, t₁ = 4 s. I=q/t₁=16•10⁻ ⁶/4=4•10⁻ ⁶ A, N=I •t₂/e =4•10⁻ ⁶• 16/1.6•10⁻¹⁹ =4•10¹⁴ .

physics
r=0.0205 m α=20⁰, m = 0.00014 kg=1.4•10⁻ ⁴ kg• F(el)=kq₁•q₂/r²=kq²/r², T•sin α =F(el)= kq²/r², T•cosα=mg . T•sin α/ T•cosα= kq²/r²mg, tanα = kq&#...

Physics
q₁ = 5 μC =5•10⁻⁶ C, q₂ = - 3 μC = - 3•10⁻⁶ C, r₁ =0.5 m, r₂ = 0.8 m. k =9•10⁹ N•m²/C² E₁=k•q₁/ r₁², (directed ↑) E₂ = k•q₂/ r₂...

physics
ΔKE = 9670 – 7540 =2130 eV =2130•1.6•10⁻¹⁹= 3.41•10⁻¹⁶ J Δφ=|φ(A)-φ(B)| = 16 –(-66) = 82 V ΔKE =q• Δφ q =ΔKE/ Δφ =3.41•10⁻¹⁶/82=4.2•...

physics
C=q/ Δφ, C=εε₀A/d, q/ Δφ = εε₀A/d, q= εε₀A Δφ /d, where ε =4.1, ε₀=8.85 •10⁻¹² F/m, A=4.4•10⁻⁹m², d=1.64.4•10⁻⁸ m, N=q/e=q/...

physics capacitor
C=q/U => U=q/C

mv²/R = μmg (a) μ=v²/Rg = … (b) v₁=sqrt(μ₁Rg)

Physics
y(x,t)=Asin(kx-wt) Speed dy/dt = - Aωcos(kx-ωt), Max. speed (dy/dt)max =Aω. cos(kx-ωt) =1 => sin(kx-wt)=0 => x=0

Physics
λ=v/f v=λ•f T=m₀•v² = m₀• (λ•f)², T=M•g, m₀• (λ•f)²=Mg, M= m₀• (λf)²/g = =8•10⁻³(1.8•52)²/9.8 =7.15 kg

Physics
T=0.16 s, λ=8 m λ=vT v= λ/T= 8/0.16 =50 m/s f=1/T=1.0.16 =6.25 Hz ω=2πf =… k=2π/ λ=…

Physics
F(ten) = m₀•v² v=sqrt{F(ten)/m₀}, If m₀₂ =2m₀₁ => v₀₁=√2•v₀₂

Physics
b. P=F/A=5000/10=500 Pa

Physics
Q=π•P₁•r₁⁴/8•η• L = π•P₂•r₂⁴/8•η• L P₂=(r₁/r₂)⁴P₁= (100%/70%)⁴• P₁=4.2• P₁. c. The pressure gradient would have to increase...

physics
F=k•q₁•q₁/r², where k =9•10⁹ N•m²/C²

Physics
Q=5 cm³/min = 5•10⁻⁶/60 m³/s d=0.5 mm => r=0.25•10⁻³ m, η=1.5•10⁻³ Pa•s, L =0.05 m ρ=1025 kg/m³ Poiseuille’s law Q=π•P•r⁴/8•η• L. P = 8• Q•η...

physics
N=(q1+q2)/e = (2.4+2.8)•10⁻⁶/1.6•10⁻¹⁹ = =3.25•10¹³

Physics
m=90 kg ρ(He) =0.179 kg/m³ D=11 m => R=5.5 m. ρ(air) =1.29 kg/m³ ( 4πR³/3)•g• ρ(air)= (4 πR³/3 )•g• ρ(He) + (M+m)g, M = (4πR³/3)•{ρ(air) - ρ(He)} – m =….

Physics
sinα =3.2/35 =0.091, α=5.24⁰, tanα=0.092. T•sin α =F(el)=kq₁•q₂/r²=kq²/r², T•cosα=mg . T•sin α/ T•cosα= kq²/r²mg, tanα = kq²/r²mg, q=sqrt{ r²•m•...

science
Aurum Argentum Stannum Hydrargyrum Plumbum Kalium Wolfram Ferrum

Chemistry
a=2.77 Å= 2.77•10⁻⁸ cm. The BCC-cell volume is V=a³=(2.77•10⁻⁸)³ = 2.13•10⁻²³ cm³. Density ρ =8.65g/cm³ per unit cell. Avogadro´s number N₀=6.022•10²³ mol⁻¹...

Physics
v=350 km/h=350000/3600=97.2 m/s c=130 J/kg•K KE -> Q mv²/2 =cmΔT ΔT= v²/2c=97.2²/2• 130= 36.3 K

physics
v=s/t=750/300 =2.5 m/s λ=vT T=λ/v=16.1/2.5 =6.44 s

Physics
sinα =9/20 =0.45 α=sin⁻¹0.45 =26.7⁰

physics
α1 =360⁰-320⁰ =40⁰ F(x) =F1(x)+F2(x) =F1cosα1 + F2cosα2 = =53•cos40 +81•cos13 =40.6+78.9=119.5 N F(y) =F1(y)+F2(y) = - F1sinα1 + F2sinα2 = = - 53•sin40 +81•sin13 = = - 34.07 +18.22 = - 15.85 N F=sqrt{F(x)²+F(y...

physics
α =(360⁰ - 2•100⁰)/2=80⁰ F12=sqrt{F1²+F2²-2•F1•F2•cosα}= =sqrt{400+400-2•20•20•cos80⁰}=25.71 N Direction: F1 is directed along the positive X-axis ,and F2 is 100⁰ measured from the positive X...

Physics
v=200 km/h =200000/3600=55.56 m/s, a=(v-v₀)/t=(55.56-0 )/3=18.52 m/s², a/g= 18.52/9.8= 1.89, F=ma=12000•18.52=2.22•10⁵ N

physics
http://en.wikipedia.org/wiki/Watt P=E/t=1000/10 =100 W

science
ΔPE(A)=ΔKE(C) mgΔh₁= mv(C)²/2 v(C)=sqrt(2gΔh)= =sqrt{2•9.8•(5-2)}=7.67 m/s KE(C) =KE(B) + Δ PE(B) mv(C)²/2 =mv(B)²/2+ mgΔh₂ v(C)² = v(B)² + 2gΔh₂ v(B)=sqrt{ v(C)² -2g(3.2-2)} = … ...

Physics
Q1= rm=330000 x 0.02 = … Q2=cm(T2-T1)=4180 x 0.02 x 15 = ... Q= Q1 +Q2 = …

Physics
1 atm =101300 Paá p=p₀+ρgh= => h=(p-p₀)/ρg = =(108000 -101300)/ 9.8•1024= =0.668 m If ρ₂<ρ₁, h₂>h₁

Physics
k=30 N/m x=0.5 m E=kx²/2

Physics
k=8.98755 × 10^9 =9•10 ⁹N • m^2/C^2. q1=−6 µC, q2 =7 µC, q3 =-5 µC F12=k•q1•q2/r1²=9•10⁹•6•10⁻⁶•7•10⁻⁶/9 =…. (to the right) F13=k•q1•q3/r2²=9...

Physics
m1•v1 + 0= (m1+m2)u u= m1•v1/(m1+m2)

Physics
F=μmg μ=F/mg=99/128•9.8= 0.079

physics
http://en.wikipedia.org/wiki/Refraction http://en.wikipedia.org/wiki/Snell's_law http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/phase.html

physics

Physics
(a) v₁= (m₁-m₂)v₁₀/(m₁+m₂), v₂={2m₁v₁₀}/(m₁+m₂). (b) u=m₁V₁₀/(m₁+m₂)

physics
s=at²/2 a=2s/t² ma=mgsinα sinα=a/g

Physics
m₁v₁=(m₁+m₂)u u= m₁v₁/(m₁+m₂)

Physics
mv²/(R+h) = GmM/(R+h)² v=sqrt{GM/(R+h)} =…. the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,

Physics
tanα=0.55/0.4 =1.375. α=54⁰ The distance between the charges d = sqrt(0.4²+0.55²) = 0.68 m The electric field at the disired point is zero => k•q₁/0.68+r)²=k•q₂/r², 0.86r²-1.36r-0.46=0, r ={1.36±sqrt(1.85...

physics
m₁a=m₁g -T m₂a=m₂g-T a(m₁-m₂)=g(m₁+m₂) a =g(m₁+m₂)/(m₁-m₂)= ...

physics
f=1.6 Hz λ=1.5 m v= λf=1.5•1.6=2.4 m/s L=vt/2=2.4•2.9/2=3.48 m.

V₁= abc=2•3.5•4 = 28 in³ V₂=A•h=(πD²/4) •h= =3.14•3.2²•3.5/4=28.15 =28.2 in³ V₂ > V₁

Math I REALLY NEED HELP!!!!!!!!!
V= 5 x 11.8 x4.4 =259.6 dm³ =259.6 L

Physics THRUST
a= (v₂²-v₁²)/2h = =(0.5²-20²)/2•100= - 2 m/s² F=m(a-g)= 20000•(2-1.62) =2.76•10⁴ N

physics
KE=ΔPE=412 J mv²/2=mgh v=sqrt(2gh)

physics
PE=mgh=57 x 9.8 x3.7 =...

Physics
e) The new force is the same.

Math
Perform the indicated operations. Reduce the answers to lowest terms.... 1.) 7 3/5 + 2 4/7 = _______________ 2.) 8 5/9 + 15 5/6 =________________ 3.) 14 5/10 + 8 3/5 = ________________ 4.) 5/6 x 3/4 = _____________________ Reduce each fraction to lowest terms. Write improper ...

Post a New Question