Sunday
April 26, 2015

Posts by Elena


Total # Posts: 4,364

physics
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², R1=r/2 => F1=4F
November 26, 2012

physics
weight=buoyant force mg= F d₁•V•g =k•d₂•V•g k= d₁/d₂ =980/1025 =0.956
November 26, 2012

physics
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², PE₁=G•m₁•m₂/R₁ PE₂=G•m₁•m₂/R₂ E=ΔPE= PE₁-PE₂= =G•m₁•m₂/R₁-G•m₁&#...
November 25, 2012

Physics
p₁=8.9•10⁻²³ kg•m/s p₂=5.35•10⁻²³ kg•m/s Law of conservation of linear momentum 0=vector p₁+vector p₂+vector p, 0=vector p₁₂ + vector p, p₁₂=sqrt(p₁²+p₂²...
November 25, 2012

Physics
d•sinθ=k•λ N₀=1/d => λ=sinθ/k•N₀ sin30°=0.5, N₀=2•10⁵ m⁻¹ k=1: λ=sinθ/k•N₀=sin30°/1•2•10⁵=2.5•10⁻⁶ m invisible - Infra-red k=2 λ=sin...
November 25, 2012

Physics
(a) v=v₀-at a=( v-v₀)/t=(38.666-39.486)/0.231 =-3.55 m/s² F(dr)=ma=-0.209•(-3.55)=-0.7419 N (b) F(dr)=μN=μmg μ=F(dr)/mg=0.7419/0.209•9.8=0.362 (c) Work-energy theorem ΔKE=W(dr) 0-mv²/2=F•s. F= - mv²/2s= - 0.209•...
November 25, 2012

physics
Polarimetry, or polarization, determines sucrose concentration by passing polarized light through a solution. It determines the sugar content of solutions by measuring the angle of rotation of the plane of polarization of a light beam. The amount of rotation is proportional ...
November 25, 2012

PHYSICS
Polaroid filters are incorporated into sunglasses. Because the light reflecting off most surfaces will tend to be partly polarized with a predominance of the electric fields oscillating horizontally, that “glare” can be diminished by having the transmission axis of ...
November 25, 2012

Science
Correct answers. http://hyperphysics.phy-astr.gsu.edu/hbase/elacol2.html#c3
November 25, 2012

physics
F(fr)=μN=μmg
November 24, 2012

Physics
Internal energy is U=3•n•R•T/2 => chage in internal energy is ΔU=3•n•R•ΔT/2. From the ideal gas law PV=nRT => n•R•ΔT=nR(T2-T1)=p2•V2 =p1•V1=p(V2-V1) => ΔU=3•n•R•ΔT/2=3•p(V2-...
November 24, 2012

Physics
Internal energy is U=3•n•R•T/2 => chage in internal energy is ΔU=3•n•R•ΔT/2. From the ideal gas law PV=nRT => n•R•ΔT=nR(T2-T1)=p2•V2 =p1•V1=p(V2-V1) => ΔU=3•n•R•ΔT/2=3•p(V2-...
November 23, 2012

Physics
1/f=1/di + 1/do 1/6=1/di + 1/8 Solve for ‘di’
November 23, 2012

Physics
x=kLλ/d k=3, L=2.51 m, d=5.35•10⁻⁶ m x₁= kLλ₁/d=3•2.51•640•10⁻⁹/5.35•10⁻⁶=0.9 m, x₂= kLλ₂/d=3•2.51•425•10⁻⁹/5.35•10⁻⁶=0.595 m, tan&#...
November 23, 2012

Physics
Internal energy is U=3•n•R•T/2 => chage in internal energy is ΔU=3•n•R•ΔT/2. From the ideal gas law PV=nRT => n•R•ΔT=nR(T2-T1)=p2•V2 =p1•V1=p(V2-V1) => ΔU=3•n•R•ΔT/2=3•p(V2-...
November 22, 2012

Physics
Internal energy is U=3•n•R•T/2 => chage in internal energy is ΔU=3•n•R•ΔT/2. From the ideal gas law PV=nRT => n•R•ΔT=nR(T2-T1)=p2•V2 =p1•V1=p(V2-V1) => ΔU=3•n•R•ΔT/2=3•p(V2-...
November 22, 2012

Physics
m1•v1=(m1+m2)v v1=(m1+m2)v/m1=(0.01+3.99)0.5/0.01=200 m/s
November 21, 2012

Physics
t= 2vₒ•sinα/g L=vₒ²•sin2α/g, h= vₒ²•sin²α/2g,
November 21, 2012

Physics
(a) PE= mgx=1.9•9.8•(1.13-3)= - … (b) PE =mgh=1.9•9.8•(3-1.13)= + … (c) ΔPE=0
November 21, 2012

math
23/24-15/24=(23-15)/24=8/24=1/3
November 20, 2012

physics
V1=4πR³/3=4π20³/3=33510 m³ T1-279K T2=305K V1/T1 =V2/T2 V2=V1•T2/T1
November 20, 2012

physics
Max displacement is the amplitude => A=26.6 cm
November 20, 2012

Physics
W=Fs=120•5 = 600 J W(fr)=100•5=500 J ΔKE=(120-100)•5=100J
November 20, 2012

Physics
mgh=4•9.8•1.5=... mgH=4•9.8•6.5 =...
November 20, 2012

physics
k =200 rad/m k=2π/λ => λ=2π/k=2π/200 =π/100=0.0314 m x= λ/2=0.0314/2=0.0157 m
November 20, 2012

Physics
F(x)= -F1+F2•cos α= =-23 +33.8•cos39°= 3.27 N F(y) = F2•sin α =33.8•sin39°= 21.27 N F(net) =sqrt{F(x)²+F(y)²}= sqrt{3.27²+21.27²}=21.52 N
November 20, 2012

Physics
-F1+F2•cos α=-23 +33.8•cos39°= 3.27 N
November 20, 2012

university physics
for Pt α =0.00392 (1/℃). R₁=R₀[1+α(T₁-T₀)] R₂= R₀[1+α(T₂-T₀)] R₁/R₂=[1+α(T₁-T₀)]/[1+α(T₂-T₀)] 200/253.8=(1- 0.00392 •20)/[1+ 0.00392• (T₂-20)] ...
November 20, 2012

Physics
mv²/2=mgh h= v²/2g
November 20, 2012

PHYSICS
c = e > a > d > b
November 20, 2012

physics
M/m=1
November 20, 2012

Physics
The law of conservation of linear momentum for inelastic collision m1•v1 - m2•v2=(m1+m2)•u u= {m1•v1 - m2•v2}/(m1+m2)= ={0.241•1.53 -0.321•2.49)/(0.241+0.321)= =-0.766 m/s. (in the direction of the second pizza motion)
November 19, 2012

Physics
Cosine Law u=sqrt(V²+v²-2•V•v•cos135°)= =sqrt(200²+90²-2•200•90•cos135°)= =sqrt(40000+8100 +25455.8)=271 km/h s=u•t=271•3=813 km Sine Law 271/sin135°=90/sinβ sinβ=90•sin135°/271=0.235 &#...
November 19, 2012

Physics
(a) Centripetal (or normal) acceleration is a(c)= m•v²/R=… (b) Tangential acceleration a(τ)= 1 m/s² a=sqrt{a(c)² +a(τ)²}=... (c)tanα= a(c)/a(τ)= ..
November 19, 2012

physics
ω=2π/T=2•3.14/7•10⁻⁵=… x(max) =A. v(max)=Aω => A= v(max)/ω=…
November 19, 2012

Physics
The mass of gravel is m2=441•2.67 = 1177.47 kg The law of conservation of linear momentum m1•v1= (m1+m2)v2 v2= m1•v1/(m1+m2) = =2150•2.29/(2150+1177.47)=1.48 m/s
November 19, 2012

Physics
c)
November 19, 2012

Physics
m1•v1 =(m1+m2)v v= m1•v1/m1+m2)
November 19, 2012

Physics
h₁=40 m, h₂=5m, v₁=15 m/s PE1+KE1 =PE2+KE2 mgh₁+mv₁²/2= mgh₂+ mv₂²/2 Solve for v₂
November 19, 2012

Physics
(a) Centripetal (or normal) acceleration is a(c)= m•v²/R=… (b) Tangential acceleration a(τ)= 1 m/s² a=sqrt{a(c)² +a(τ)²}=... (c)tanα= a(c)/a(τ)= ..
November 19, 2012

Physics
Find the solution in Related Questions
November 19, 2012

Physics
Δp=FΔt Δp= mv₂-(-mv₁)= m(v₂+v₁), m(v₂+v₁)=FΔt F= m(v₂+v₁)/Δt= =0.148•(10.1+8.95)/10.1•10⁻³=132.6 N
November 19, 2012

physics
λ=v/f f= v/λ
November 19, 2012

physics 209
s=at²/2 => a=2s/t²=2•0.4/2²=0.2 m/s² The equation of the load motion ma=mg-T => T=m(g-a) The equation of the pulley motion Iε=M-M(fr) M(fr) = M-Iε = TR-Ia/R= =m(g-a)R – Ia/R = ...
November 19, 2012

physics, university
m=0.05 kg, ρ =11•10⁻⁸ Ω/m d=7860 kg/m³ R=1.5Ω R= ρ•L/A d=m/V=m/A•L R/d= ρ•L²•A/A•m = ρ•L²/m. L=sqrt{m•R/ρ•}=… A= ρ•L/R = … A=πD²/4 D=sqrt(4A...
November 19, 2012

physics, university
J=nev, where J is the current density, n is free electron density, e=1.6•10⁻¹⁹C , drift velocity v= 2.98•10⁻⁴ m/s J=U/RA, where U=10 V, R=0.2 Ω, A= πr² n•e•v= U/R•π•r² n= U/R•π•r...
November 19, 2012

Physics
h₁=40 m, h₂=5m, v₁=15 m/s PE1+KE1 =PE2+KE2 mgh₁+mv ₁²= mgh₂+ mv₂²/2 Solve for v₂
November 19, 2012

Physics
m1•v1 =(m1+m2)v v= m1•v1/m1+m2)
November 19, 2012

Physics
P =mgh/t, t=20 min =1200 s
November 19, 2012

physics
λ=v/f=s/tf=2.5/1.7•3=0.49 m
November 19, 2012

Physics
m•a=F(fr) m•v²/R=μ•m•g v=sqrt(μ•R•g)
November 19, 2012

Physics
Flows to the Earth ΔS(E)=1000/290 =3.448 J/K Flows out of the Sun ΔS(S)=-1000/5700 =- 0.1754J/K ΔS= ΔS(E)+ ΔS(S)= 3.448-0.1754=3.2726 J/K
November 19, 2012

Physics
(3500-2500)•30/4100=7.32 pounds
November 19, 2012

Physics
Coefficient of performance = energy removed from fridge / ( total energy expelled – energy removed from fridge ) k=Q1/(Q-Q1) Q=Q1(k+1)/k=2.4•10⁴•5/4=3•10⁴ J
November 19, 2012

Physics
η =1 –T(cold)/T(hot) = = 1- (273+18)/(273+22) = =1-291/493 = 0.41
November 19, 2012

Physics
Thermal E~kT, where k is the Boltzmann constant, T is the temperature in Kelvins 5℃=278K Answ. 278 x 2=556 K
November 19, 2012

Physics HELP!
(a) Compare x = (7.1 cm) sin (2.1π t) with x=Asin(ωt) Then ω= 2.1π, => T=2π/ ω = = 2 π/2.1π=0.7 rad/s (b) f=1/T=1.42 Hz (c) A=7.1 cm (d) x=Asin(ωt) 2.6 = 7.1 sin (2.1π t) sin (2.1π t) =2.6/7.1=0.366 (2.1π t)=sin&#...
November 19, 2012

Physics URGENT!!!
k=F/Δx=8.4/0.0214 = 393 N/m ω= sqrt(393/1.3)=302.3 rad/s ω=2πf f= ω/2π=302.3/2•3.14 =48.14 Hz
November 19, 2012

Physics
b) False
November 18, 2012

Physics
Δ=2bn-λ/2 = 2k(λ/2) 2bn =(2k+1)λ/2 λ=4bn/(2k+1) For k=0, λ=4bn=4•1.25•10⁻⁷•1.38=6.9•10⁻⁷m= =6.9•10⁻⁵cm ============= λ=3mm=3•10⁻³m v=340 m/s f=v/ λ=340/3•...
November 18, 2012

physics
(a) At the point D ma=mg mv²/r=mg v=sqrt(g•r)=sqrt(9.8•2.87)=5.3 m/s (b) KE(C)=PE+KE= =mg•2r+mv²/2= =m(2gr+5.3²/2)=54.8 J. (c) KE(B)=KE(C) + W(fr)= = KE(C) + μ•mg•s= =54.8+0.29•0.78•9.8•4.08= =63.8 J (d) PE1=KE(B) mgh...
November 18, 2012

Physics
Problem#62 http://www.physics.umn.edu/classes/2012/fall/Phys%201401V.001/downloads/169171-Ch09_ISM.pdf
November 17, 2012

physics
(a) ma=mgsinα sinα=a/g=5/9.8 =0.51 α=30.7° (b) s=at²/2 t=sqrt(2s/a)=... (c) the same acceleration
November 15, 2012

physics
KE=mv²/2
November 15, 2012

Physics. Please please help!
Δφ=φ₁-φ₂=kQ/r₁-kQ/r₂= =kQ(r₂-r₁)/r₁•r₂= =9•10⁹•4.5•10⁻⁶•8•10⁻²/20•10⁻⁴=1.62•10⁶ V mv²/2= q•Δφ, v= sqrt...
November 14, 2012

physics
n₀= 9.80 101 rev/min =….rev/s ε=2 rad/s² 2•π•n=2•π•n₀ - ε•t, since n=0, 2•π•n₀ - ε•t=0, t=2•π•n₀/ ε=… φ=2•π•n₀•t- &#...
November 14, 2012

Physics
W=(F,s)=F•s•cosα = =8740•1130•cos180º= =8740•1130•(-1)= = -9876200 J
November 14, 2012

Physics HW Help, Please
mg=76300 N, m=76300/9.8 kg, s= 418 m, v₀=66.5 mph =29.7 m/s v=28.9 mph=12.2 m/s, h=10.7 m KE1-KE2= W(dr)+ PE m•v₀²/2 - m•v²/2= F(dr) •s +m•g•h Solve for “F(dr)” Answer this Question
November 12, 2012

Physics
The amplitude at resonance (ω₁ = ω₀) ia Ar =F₀/b•ω₀, A/Ar=A/( F₀/b•ω₀)= { b•ω₀/m}/sqrt{( ω₁²- ω₀²)²+(b²•ω₁²/m²)}= =1/sqrt{(m&#...
November 12, 2012

Physics
hole d=0.09 m ball D=d+Δd=d+10⁻⁵m=0.09001 m t=27.3℃ ΔL=αLΔT D+ΔD = d+Δd D+ α1•D•ΔT =d + α2•d•ΔT D-d = α2•d•ΔT - α1•D•ΔT= ΔT(α2•d- &#...
November 9, 2012

physics, help!!
q = Ne=- (8.2•10⁹•1.6•10⁻ ¹⁹)= =- 1.36•10⁻⁹ C. q(sph)+q =4•10⁻⁹ - 1.36•10⁻⁹ = + 2.64•10⁻⁹ C
November 9, 2012

Physics
The drops begin to move with horizontal speed v(x)=2•π•n•R=2•π•N•R/t= =2•π•22•0.5/44=1.57 m/s The time for falling down is t=sqrt(2h/g) = sqrt(2•1.5/9.8)=0.55 s. L=v(x) •t =1.57•0.55 =0.87 m
November 9, 2012

Physics
Change in velocity vecorΔv =vecor v₂-vecorv₁
November 9, 2012

Physics
Change in velocity Δv⃗=v⃗₂-v⃗₁ |Δv|=sqrt(v²+v²-2v•v•cos60°)=sqrt(2v²(1-cos60°))= =sqrt{2•60(1-0.5)}=7.74 m/s The distance covered by the car is s= 2•π•R•60°/360°=2•&#...
November 9, 2012

Physics
F=ma=mv²/R = =9.1•10⁻³¹• (2.3•10⁶ )²/ 5.1•10⁻¹¹= =9.45•10⁻⁸ N
November 9, 2012

Physics
http://answers.yahoo.com/question/index?qid=20090929074248AA1Q7sZ
November 8, 2012

physics URGENT! HELP
v₀ =21.82 mi/h, H= 1.60 x 102 ft. Upward motion h=v₀²/2g Downward motion H+h=v²/2g. v=sqrt{2g(H+h)}
November 7, 2012

physics
v₀ =21.82 mi/h, H= 1.60 x 102 ft. Upward motion h=v₀²/2g Downward motion H+h=v²/2g. v=sqrt{2g(H+h)}
November 7, 2012

Physics
a1=ω²•R1 a2=ω²•R2 a1/a2= R1/R2 a2=a1•R2/R1
November 7, 2012

physics
T=2•π•r/v=2•π•sqrt(r³/GM) T²=4π²r³/GM, r=cuberoot{GMT²/4π²}=.... v=sqrt(GM/r)=.....
November 7, 2012

physics
a=4.7g =v²/R v=sqrt(4.7•9.8•15)=26.3 m/s
November 7, 2012

physics
φ=90°=π/2 ω= φ/t a= ω²R= φ²R/t²=π²•0.59/0.31²=60.6 m/s²
November 7, 2012

physics
I1=m1•r² I2=m2•r² I3=m3•r²
November 7, 2012

Physics HELP!
M= m•g•L•sinα=7.4•9.8•2.1•sin3°=7.97 N•m
November 7, 2012

Physics
Before collision PE=KE m•g•h =m•v²/2 v=sqrt(2•g•h)= v₁₀=v₂₀=sqrt(2•9.8•5.8)=10.7 m/s (b) After collision v₁= {-2m₂•v₂₀ +(m₁-m₂)•v₁₀}/(m₁+m₂...
November 7, 2012

Physics
When the objects are moving in opposite directions v₁= {-2m₂•v₂₀ +(m₁-m₂)•v₁₀}/(m₁+m₂) v₂={ 2m₁•v₁₀ - (m₂-m₁)•v₂₀}/(m₁+m₂)
November 7, 2012

Physics
On the Earth mg=GmM/R² In the spacecraft mg'=GmM/(5R)²= {GmM/R²}/25=mg/25 His weight is 50.0/25 =2.0 N
November 7, 2012

Physics
tan α=ma₁/mg = (mv₁²/r)/mg= v₁²/rg tan β=ma₂/mg = (mv₂²/r)/mg= v₂²/rg tan α/ tan β= v₁²/v₂² v₂ = v₁•sqrt(tan β/tan α)=18.5•sqrt(tan16/tan11)= =22....
November 7, 2012

physics
Q=c•m•ΔT For brass c= 385 J/kg•K ΔT= Q/c•m=760/385•1=1.97º
November 7, 2012

physics
Q=c•m•ΔT For brass c= 385 J/kg•K ΔT= Q/c•m=760/385•1=1.97º
November 7, 2012

physics
KE of the objects transforms into PE, and then PE→KE => v(start) =v(land)
November 7, 2012

Physics
F(fr) =2•μ•N=m•v²/R R= m•v²/2•μ•N=6•10⁻³•17²/2•0.73•1.8 = …
November 7, 2012

Physics Help!
β = ΔV/V•ΔT β =10•10⁻⁴(1/℃) ΔV=β•V•ΔT=10•10⁻⁴43.3•10⁻³•(34.5-14.5)=8.66•10⁻⁴ m³=0.866 liter.
November 6, 2012

Physics Help!
Linear expansion coefficient α=ΔL/L•ΔT For steel α =12•10⁻⁶ (1/℃) ΔL=α• L •ΔT= =12•10⁻⁶•514•(32.7+20.3)=0.327 m
November 6, 2012

physics
r= v²/a
November 6, 2012

Physics B
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², R= 0.241 m F13= G•m1•m3/R² F23= G•m2•m3/R² F23-F13= =G •m3• (m2-m1)/R²= =6.67•10⁻¹¹•41.1&#...
November 6, 2012

Physics
T=2•π•r/v=2•π•sqrt(r³/GM) T1=T2
November 6, 2012

physics
T2=mg/sin52 =57/0.788=72.3 N T1 = T2cos52=72.3•0.616= 44.5 N
November 6, 2012

physics
F(fr) =μ(s) •m•g•cosα
November 6, 2012

physics
T=F(fr) =μ(s) •m•g
November 6, 2012

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