Tuesday

October 21, 2014

October 21, 2014

Total # Posts: 4,334

**physics**

v=ω•R=2π•n•R =2π•(1800/60) •0.26=… a(centripetal) = v²/R=…
*December 3, 2012*

**Physics- Elena 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=...
*December 3, 2012*

**Physics**

F=F(fr)=μN=μmg
*December 3, 2012*

**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*

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