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August 22, 2014

Posts by Elena


Total # Posts: 4,331

Physics- Someone Please Help!!!
Mass per unit length m(o) =0.011 kg/m T=46 N Speed in the stretched string is v = sqrt(T/m(o)) =sqrt(46/0.011)= 64.7 m/s λ=2L=1.2 m f=v/ λ=64.7/1.2=53.9 Hz Resonant frequency F(n)=n•v/2L=n(64.7/1.2)=53.9•n=20000 n=20000/53.9 =370 => f(n)= n•v/2L=370...
December 3, 2012

Physics URGENT!!!
f(n) = nv/2L The lowest frequency is f1=v/2L =343/2•0.306=560 Hz. Distance between adjacent antinodes is λ/2 and λ=v/f So λ2=v/2f=343/2•41000 =0.0042 m
December 3, 2012

Physics
Average speed= total distance /time taken= = 3200/13.5•60 =3.95 m/s Average velocity = total displacement/time taken = 0.
December 3, 2012

physics
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,
December 3, 2012

Physics
b. emitted electrons are more energetic Einstein's relation for phptoelectric effect: hc/λ=v W= KE, λ↓ KE↑
December 3, 2012

Physics!!!
y=3.17cos38.6 =3.17 •0.78=2.48 h= 3.17 - 2.48=0.69 v=3.68 m/s
December 2, 2012

physics
KE=mv²/2 v=sqrt(2KE/m)
December 1, 2012

Physics HW Help, Please
E= mv²/2
December 1, 2012

physics
Pascal’s principle F1/A1=F2/A2. F(bc)={A(bc)/A(mc)}•F(pedal) = =(1.83/6.32) •49 =14.2 N This is the normal force exerted on the brake shoe. The frictional force is F(fr) =μ F(bc)=0.442•14.2 =6.3 N
November 30, 2012

PHYSICS - PLEASE HELP
W=m•g•h=m•g•d•sin30
November 30, 2012

PHYSICS - PLEASE HELP
W=m•g•h=m•gvdvsin30
November 30, 2012

Physics
U =mgh-mv²/2
November 30, 2012

Physics
by 4
November 30, 2012

PHYSICS - PLEASE HELP
(A) KE₁=m₁v₁²/2= (m₁v₁)²/2 m₁=p₁²/2m₁ KE₂=m₂v₂²/2= (m₂v₂)²/2 m₂= p₂²/2m₂ KE₁=KE₂ p₁²/2m₁=p₂²/2m₂ p₁...
November 30, 2012

physics
Δy=Lλ/d = 1•500•10⁻⁹/0.001=…
November 30, 2012

physics
ΔPE=m•g•h=m•g•s•sinα
November 30, 2012

physics
ΔKE=ΔPE +W(fr)= m•g•s•sinα+μ•m•g•s•cosα= =m•g•s(sinα+μ•cosα)
November 29, 2012

Physics
v⒳=v₀•cosα v⒴=v₀•sinα L=vₒ²•sin2α/g, h= vₒ²•sin²α/2g, t= 2vₒ•sinα/g
November 29, 2012

physics
mgh₁=mv₁²/2 mgh₂=mv₂²/2= m(3.9v₁)²/2=15.21 mv₁²/2 h₂=15.21h₁
November 29, 2012

Physics, Please Help
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², R=h+R(Earth)= (455+6370)•10³ m
November 29, 2012

PHYSICS PLEASE HELP ME
The law of conservation of linear momentum vector p₁ +vector p₂ =vectorp₁`+vector p₂` Projections on the axis x and y p₁⒳ +p₂⒳= p₁`⒳+p₂`⒳ p₁⒴ +p₂⒴= p₁`⒴+p₂`⒴...
November 29, 2012

science
stratovolcano
November 29, 2012

physics
p₁+ρ‧ν₁²/2 +ρ‧g‧h₁ = p₂+ρ‧ν₂²/2 +ρ‧g‧h₂ p₁ = p₂+ρ(ν₂²-ν₁²)/2 +ρ‧g(h₂-h₁)= =141855 +1354‧...
November 29, 2012

physics
(a) continuity equation: A₁v₁=A₂v₂ π‧d₁²/4‧v₁=π‧d₂²/4‧v₂ v₂=v₁(d₁/d₂)² =82.4 m/s. (b) p₁=1.4 atm = 141855 Pa h₂-h₁ =-7.82 m Bernoulli ...
November 29, 2012

Physics
a=F/m
November 29, 2012

Physics
F=k•q1•q2/r² k =9•10^9 N•m²/C²
November 29, 2012

math
Write the expression thrice the sum of m and 8
November 27, 2012

Physics
Units????????
November 27, 2012

Physics
F(total) =4748 -3969 =779 (directed to the east) Win – Theta Chi It’s better to pull straight on
November 27, 2012

physics
The pressure at the depth d p1= ρ•g•d + p (atm) =1024•9.8•18.9 + 101325 =2.91•10 ⁵ Pa, The pressure at the height h p=p₀exp{-μgh/RT) Since we don’t know the temperature, we use another expression. Air pressure above sea level...
November 27, 2012

Physics
sinα=1/20=0.05 sinα=h/s => h=s•sinα W=ΔPE=m•g•h=(m₁+m₂)•g•s•sinα=..
November 27, 2012

physics
m₁=1500 kg, m₂=2500 kg, v₁=5mph=2.24 m/s, claimed velocity is u=10 mph=4.47 m/s, real speed of the pickup is v₂=? μ=0.49, s=5 m. Law of conservation of linear momentum m₁•v₁+m₂•v₂=(m₁+m₂)•v, law of...
November 26, 2012

Physics
m=2.5 kg. R=D/2=0.1 m, n₀=3600 rpm=3600/60=60 rev/s t=10 s. F=? 2πn=2πn₀-εt. Final n=0 2πn₀ = εt. ε =2πn₀/t. Newton’s 2 law for rotation: Iε=M. If the wheel is disc I=mR²/2, M=FR. Then (mR²/2) •...
November 26, 2012

Physics
Tuning fork has frequancy f= 200 Hz +> it makes 200 oscollations during 1 s. Since 1 min=60 s, it makes 200•60=12000 oscillations/min. Each oscillation = 4A=4•0.13 cm=4•0.0013 m=0.0052 m. Therefore, s=0.0052•12000=62.4 m.
November 26, 2012

physics
Ampere’s force F=ILBsinα F(ℓ)=F/L=IBsinα=7.5•0.7•sin45 = ...
November 26, 2012

Physics
F(fr)=μN=μmg=0.032 •55.2•9.8=....
November 26, 2012

physics
Δp=(m1+m2)Δν=(66+7.1)(9.4-6.5)=202 kg•m/s
November 26, 2012

Physics
t= 2vₒ•sinα/g
November 26, 2012

physics
h=gt²/2 t=sqrt(2h/g) L=v•t=36•sqrt(2•162/9.8)=… v(x)= 36 m/s v(y)=gt=g•sqrt(2h/g)=...
November 26, 2012

physics
T=2•π•sqrt(m/k) Solve for ’m’
November 26, 2012

physics ..PLEASE HELP ASSIGN DUE SOON :(
http://answers.yahoo.com/question/index?qid=20121124093302AA02rcf
November 26, 2012

physics
T=2π•sqrt(L/g) g=3.7 m/s² Solve for ‘L’
November 26, 2012

physics
T=2π•sqrt(L/g) g=9.8 m/s² Solve for ‘L’
November 26, 2012

Physics
Flows to the Earth ΔS(E)=6000/295 =20.34 J/K Flows out of the Sun ΔS(S)=-6000/5650 =- 1.062 J/K ΔS= ΔS(E)+ ΔS(S)= 20.34 -1.062= 19.278 J/K
November 26, 2012

Physics
Q=r•m ΔS=Q/T₀=r•m/T₀=333•10⁵•0.0951/273=1.16•10⁴ J/K If environment temperature is T, ΔS= - Q/T= - 333•10⁵•0.0951/T= …
November 26, 2012

Physics
m = W•T1/(T1-T2)• r =...
November 26, 2012

Physics
T1=273+170=443 K T2=273+23=296 K efficiency =(Q1-Q2)/Q1 =W/Q1 efficiency =(T1-T2)/T1 W/Q1 = (T1-T2)/T1 Q1=W•T1/(T1-T2) Q1= r•m r= 333•10⁵ J/kg W•T1/(T1-T2) =r•m r= W•T1/(T1-T2)•m=...
November 26, 2012

Physics
W=1,300 J Q2=6,100 J Q1 =? W=Q1-Q2 Q1=W+Q2 efficiency =(Q1-Q2)/Q1 =W/Q1
November 26, 2012

Physics
W= - p•ΔV = -0.8•(-5)•10⁻³•1.013•10⁵ = =405.2 J ΔU =Q+W=-380+405.2=252 J
November 26, 2012

Physics
(a) Ti=273+7.4=280.4 K Vi/Ti = Vf/Tf Vi/280.4 =8 Vi/Tf Tf=8•280.4 = 2243.2 K b) p•ΔV=νRΔT ν =1 mol p•ΔV= RΔT W = p•ΔV= RΔT= = 8.31•(2243.2-280.4)= =1.63•10⁴ J =16.3 kJ
November 26, 2012

physics
When the cart is 14 cm from the left end of the track, it has a displacement of x=14 -11 cm =3 cm= 0.03 m from the equilibrium position. The speed of the cart at this distance from equilibrium is v=sqrt{k(A²-x²)m}=…
November 26, 2012

The Binding Energy of Electrons?
Energy of photon: E = hc/λ h = Planck’s constant = 6.626•10⁻³⁴ J•s = 4.14•10⁻¹⁵ eV•s c = speed of light = 3•10⁸ m/s λ = wavelength = 0.954 nm = 0.954•10⁻⁹m E = 4.14•10⁻...
November 26, 2012

physics
A=4.2 cm = 0.045 m. v(max) =Aω=A•sqrt(k/m)=...
November 26, 2012

physics
T=2•π•sqrt(m/k)= 2•π•sqrt(0.223/10.20)= …
November 26, 2012

Physics
Flows to the Earth ΔS(E)=6000/295 =20.34 J/K Flows out of the Sun ΔS(S)=-6000/5650 =- 1.062 J/K ΔS= ΔS(E)+ ΔS(S)= 20.34 -1.062= 19.278 J/K
November 26, 2012

PHYSICS - PLEASE HELP
mv=MV M=mv/V=9.6•0.53/0.12=42.4 kg
November 26, 2012

Physics
Mv²/2 =4mcΔT ΔT = Mv²/8mc=1750•28²/8•8•448=47.9℃
November 26, 2012

PHYSICS
KE=mv²/2 ½KE=mcΔT ΔT= KE/2mc= mv²/4mc= = v²/4c=390²/4•130=292.5℃
November 26, 2012

Physics Can you help me get started
http://answers.yahoo.com/question/index?qid=20100629105308AAL8TBp
November 26, 2012

Physics
p=mv=2.3•10⁶•6•10⁶=13.8•10¹² kg•m/s. p₁= m₁v₁= 5.2•10⁵•2•10⁶=10.4•10¹¹kg•m/s. p₂=m₂v₂=8.4•10⁵•9•10 ⁵=75.6•10¹...
November 26, 2012

PHYSICS
For water, density is ρ =1000 kg/m ³, V =4•10¹¹ m³ => m=ρ•V=1000•4•10¹¹ =4•10¹⁴ kg, c =4183 J/kg•K, ΔT=11-9 =2 K. E=Q= m•c• (T₁-T)= m•c• ΔT =4•10¹...
November 26, 2012

PHYSICS
mgh=mv²/2 mv²/2=mcΔT => mgh=mcΔT gh=cΔT c =4183 J/kg•K, ΔT=gh/c=9.8•807/4183 =1.9° T1=T+ ΔT=16.7+1.9=18.6℃
November 26, 2012

Physics
Cu: m₁=0.1 kg, c₁=385 J/kg•K, T₁=460 K, Al: m₂=0.2 kg, c₂=930 J/kg•K, T₂=220 K, Water: m₃=0.5 kg, c₃=4183 J/kg•K, T₃280 K. T=? m₁c₁(T₁-T) = m₂c₂(T-T₂) +m₃c₃(T-T...
November 26, 2012

optics
http://www.optiboard.com/forums/showthread.php/18768-Need-Help-For-Ophthalmic-Question! and page 30 from http://www.optometry.co.uk/uploads/articles/949e0d09ac024c2edb6d55bad5da4d11_jalie20050225.pdf
November 26, 2012

physics
k = 1080 N/m, r = 0.0143 m, A = πr²= π•0.0143²=6.42•10⁻⁴ m² The pressure P = F/A = ρ•g•h, where water density is ρ = 1000 kg/m³ g = 9.8 m/s² , x = 0.0075 m For the elastic force of the spring F = kx. ...
November 26, 2012

physics/optics
Try this http://www.opticampus.com/files/introduction_to_ophthalmic_optics.pdf
November 26, 2012

physics
¹⁵₈O + ₋₁⁰e=¹⁵₇N
November 26, 2012

Physics
0=v-at a=v/t F=ma=mv/t (a) F₁ =m•v/t₁= =60.8•5.31/4.52•10⁻³=71426.5 N (b) F₂=m•v/t₂ = =60.8•5.31/0.209 = 1544.7 N. (c) mg=60.8•9.8=595.8 N ground force: F=F₁+mg=71426.5+595.8=72022.3 N F=F₂+mg=1544.7+...
November 26, 2012

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

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