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August 1, 2014

Posts by Elena


Total # Posts: 4,343

physics
CoP=4.5 CoP=Qh/(Qh-Qc)=1/{1-(Qc/Qh)}=4.5 Qc/Qh=0.78 Qc=46.1 cal Qh= Qc/0.78 = 46.1/0.78=59.1 cal

physics
c₁=129 J/kg•℃, m₁ =2.6 kg,t₁ =90℃ c₂=4180 J/kg•℃,m₂=0.21 kg, t₂=23℃ t=? Q₁=c₁m₁(t₁-t) Q₂=c₂m₂(t-t₂) Q₁=Q₂ => c₁m₁(t₁-t) = c...

physics
F= mv²/R

physics
Q=cm(t₂-t₁) Q= 1502 J, m=0.032kg, t₁=29℃ c=387 J/kg•℃ Solve for t₂

physics
Increasing the wavelength of the light, Changing the metal, Decreasing the frequency of the light

science
a=F/m

science
Incomplete question

physics
Points: left end - A, Sam - B, center of mass - C , Joe - D , right end - E Torques about the point B: mg•BC –F(J) •BD =0 F(J) =mg•BC/BD= 430•2.8/4.6 = 261.7(N) Torques about the point D F(S) •BD - mg•CD = 0 F(S)= mg•CD/BD = 430•1.8...

Physics
m=W/g=W1/g1 g1=g•W1/W

physics
W=KE₂-KE₁=mv₂²/2 -mv₁²/2= =0.5m(v₂² - v₁²) Law of conservation of angular momentum I₁ω₁=I₂ω₂ (m₁ r₁²)(v₁/r₁)=(m₂ r₂²)(v₂/r₂) v...

physics
KE2-KE1=W(fr) =F•s mv₂²/2 - mv₁²/2 = F•s Solve for F

science
Please see the Related Questions below

Physics
W₀=mg g=GM/R². W=mg´, g=GM/(R+h)² ΔW= W₀-W gravitational constant G =6.67•10⁻¹¹ N•m²/kg², Earth’s mass is M = 5.97•10²⁴kg, Earth’s radius is R = 6.378•10⁶ m.

Physics
ω₀=2πn₀=2π•2000/60 rad/s ω=2πn =2π•150/60 rad/s ω=ω₀-εt ε= (ω₀-ω)/t=…. L₀=I ω₀=… L=I ω=… L(ave) =(L+L₀)/2

physics
ma= F(fr)= μN =μmgcosα a= μgcosα

physics
L=Iω I(hoop) =mR² I(sol.cyl)= mR²/2 I(sol.sph) =2 mR²/5 I(hol.sph) =2 mR²/3

Physics
E=mc²=320•10⁻⁶•9•10¹⁶=2.88•10¹³ J E/3.65•10⁷=2.88•10¹³ /3.65•10⁷=7.9•10⁵ L 7.9•10⁵•12.75=1•10⁷ km

Physics
v(n+1) = {v´+v(n)}/{1+(v´•v(n)/c²} v2= {v´+v1}/{1+(v´•v1/c²}= ={0.5c+0.5c}/{1+(0.5c•0.5c/c²} =0.8c. v3={0.8c+0.8c}/{1+(0.8c•0.8c/c²}...0.929 c v4=...=0.97561c, v5=...= 0.9918c v6=...=0.99726c, v7=...=0.99909c > 0.9...

Physics
0= - mg+N+Fsinα => N=mg-Fsinα => F(fr) =μN =μ(mg-Fsinα) ma=Fcosα-F(fr) = Fcosα - μ(mg-Fsinα) a=0 Fcosα =μmg- μFsinα F(cosα + μsinα)=μmg F= μmg/(cosα + μsinα)= …

Physics
0= - mg+N+Fsinα => N=mg-Fsinα => F(fr) =μN =μ(mg-Fsinα) ma=Fcosα-F(fr) = Fcosα - μ(mg-Fsinα) a=0 Fcosα =μmg- μFsinα F(cosα + μsinα)=μmg F= μmg/(cosα + μsinα)= …

physics
(a) p=mv km/h -> m/s !!! (b) F=ma=mv/t

Physics
rest energy of electron m₀c²=0.512 MeV E=mc²=1533 MeV mc² =m₀c²/sqrt(1-β²)... (1) τ=τ₀/sqrt(1-β²) …..(2) Divide (1) by (2) mc²/τ= m₀c²/τ₀ τ₀=τ• m₀...

physics
t=sqrt(2h/g) L=v• t

Physics
ma=mgsinα –F(fr) = mgsinα – μmgcosα a= g(sinα – μcosα ) = 9.8• (0.59-0.16•0.81)=4.5 m/s² The speed after the first 5 sec is v=at= 4.5•5=22.5 m/s If the net force=0, a=0 => 0 = mgsinα – μ...

science
(a) V=2.68 L = 0.00268 m³, t=37°C => T=310 K, p=743 torr =99058.246 Pa R=8.31 J/mol pV=nRT n= pV/RT = 99058.246•0.00268/8.31•310 =0.1 mol N= n•N₀=0.1•6.02•10²³=6.02•10²² molecules (b) V=5•10³ L=5 m&...

Physics
Fick’s Law M= -D•(Δρ/Δx)•A, where M = m/t = mass flux [kg/s], D= 4.9•10 ⁻⁹ m ²/s is the diffusion coefficient (diffusivity) [m²/s], Δρ/Δx is the gradient of density [kg/m⁴], A is the area [m²]. ...

physical science
v₁= {-2m₂v₂₀ +(m₁-m₂)v₁₀}/(m₁+m₂) v₂={ 2m₁v₁₀ - (m₂-m₁)v₂₀}/(m₁+m₂)

Physics
The law of conservation of angular momentum L₁ = L₂ {(MR²/2) +(mR²)}ω₁ ={(MR²/2) +(mr²)}ω₂ ω₂=ω₁{(MR²/2) +(mR²)}/{(MR²/2) +(mr²)}= =2{60•4/2 + 32•4}/(60•4/2+ 32•...

physics
Doppler effect Frequency (observed) f=c/λ=3•10⁸/5.87•10⁻⁷=5.11•10¹⁴ Hz Frequency (apparent) f´=c/λ´=3•10⁸/5.9•10⁻⁷=5.085•10¹⁴ Hz f'=cf/(c+u) u=c{(f/f´)-1} =1.53...

physics
I = P/A = P/4πr² = 100/4π(8)² = 0.12 W•m⁻² If the sound intensity level is halved to a value of I = 0.06 W•m⁻², the sound intensity level will decrease by 3 dB. I = P/4πr² = 100/4π(x) ² = =0.06 W•m...

physics
F=mg g=F/m=236/63=3.746 m/s² h=gt²/2 t=sqrt(2h/g)=sqrt(2•2.1/3.746)=1.06 s.

physics
I = P/A = P/4πr² = 100/4π(8)² = 0.12 W•m⁻² If the sound intensity level is halved to a value of I = 0.06 W•m⁻², the sound intensity level will decrease by 3 dB. I = P/4πr² = 100/4π(x) ² = =0.06 W•m...

physics
λ=4L=4•0.9=3.6 m f=v(sound)/ λ

physics
(a) Stretch in the spring is L₁=sqrt(x²+L₀²) = sqrt(0.7² +0.5²)=0.86 m Elongation is Δx= L₁-L₀= 0.86-0.5=0.36 m. E(total) = PE=2•k•Δx²/2=2•37.7•0.36²/2=4.9 J. (b) PE=KE =mv²/2 v=sqrt(2...

physics
m1= 443 kg, m2=181 kg, F(fr) = F =G•m1•m2/R², μ•m2•g= G•m1•m2/R², μ•g= G•m1/R², R =sqrt(G•m1/ μ•g).

physics
see the Related Questions below

physics
mg=GmM/R² g=GM/R² g´=GM/(R+h)² g´= 0.337g GM/(R+h)² =0.337• GM/R² R²/0.337=(R+h)²= R²+2Rh+h² h²+2Rh - 1.96R² = 0 h=- R±sqrt{R²+1.96 R²}= =-R±1.72R h=0.72R=0.72•6.38•10⁶...

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

physics
m1= 443 kg, m2=181 kg F(fr) = F =G•m1•m2/R² μ•m2•g= G•m1•m2/R² μ•g= G•m1/R² R =sqrt(G•m1/ μ•g)

Physics
http://ca.answers.yahoo.com/question/index?qid=20101003132118AAicaXe

physics
v=sqrt(T•L/m) λ=v/f => f=v/λ= sqrt(T•L/m)/ λ f₁/f₂={sqrt(T₁•L/m)/ λ}/{sqrt(T₂•L/m)/ λ} (f₁/f₂)² =T₁/T₂ T₂=T₁(f₂/f₁)² (T₂-T₁)/T₁=(...

Physics
s=v₀t+at²/2, v₀= 4.5 m/s, a= 0.04 m/s², t= 12s

Physics
a=(v-v₀)/t=v/t F=ma

physics
http://ca.answers.yahoo.com/question/index?qid=20110714100031AAk4Hfp

Physics
Find answer in the Related Questions

Physics
C=q/U =Ne/U , N=CU/e=55•10⁻ ¹²•5.3/1.6•10⁻ ¹⁹ =1.82•10⁹

Physics
closed end – node open end - antinode => A quarter of the wavelength is on the length of the pipe => λ=4L=4•0.6 = 2.4 m λ=v/f f=v/ λ=340/2.4 =141.5 Hz

Physics
A) 141.5 Hz

physics
From similar triangles: Hi/di =Ho/do => Hi/Ho=di/do =M

physics
mgh =179 m=179/mg =179/0.296•9.8 = 61.7 kg

Physics
Magnetic field due to the long wire B₁=μ₀I/2πb=4π•10⁻⁷•20/2•π•0.003=1.3•10⁻³ T ( B₁ is directed normal to the axis of solenoid) B=sqrt(B₁²+B₂²) =sqrt{(1.3•10⁻...

physics
PE=kx²/2 k=2•PE/ x²= =2•2.5/0.15²=222 N/m

physics
PE =KE =KE(trans)+ KE(rot) = mgL=mv²/2 +Iω²/2= =m ω²L²/2 + m ω²L²/3•2= =2 m ω²L²/3, ω=sqrt(3g/2L)=sqrt(3•9.8/2•1.2) = =sqrt(12.24)=3.5 rad/s

physics
mg= F =G•m •M/(R+h)² g= G•M/(R+h)² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², h=3600000 m=3.6•10⁶ m Earth’s mass is M = 5.97•10²⁴kg, Earth’s radius is R = 6.378•10...

Physics
F(fr)=μ•N=μ•m•g•cosα

Physics
F(fr)=μ•N=μ•m•g μ=F(fr)/mg

Science
The most common mineral of the Earth's continents is quartz, the mineral SiO2.

science
http://en.wikipedia.org/wiki/Ion

science
http://en.wikipedia.org/wiki/Isotope

science
http://www.chem4kids.com/files/elem_pertable.html http://en.wikipedia.org/wiki/Periodic_table

science
http://www.chem4kids.com/files/atom_bonds.html

Science
http://www.chem4kids.com/files/atom_electron.html

physics
μ=0.14, s=30 m=160 kg x: m•a= m•g•sinα - F(fr), y: 0= - m•g•cosα +N. F(fr)=μ•N= μ• m•g•cosα m•a= m•g•sinα - μ• m•g•cosα a= g(sinα - μ•cosα...

English
we are learning about the 14 tenses: past,present,future,past perfect,present perfect, future perfect, past progressive..., past perfect progressive..., emphatic..and then there is another one but i forgot what that one was. Anyway, i need a website that can help me with these...

Math
Christine currently has $5000 in her 401(k) and plans to contribute $100 each month for the next 30 years into it. What will be the value of Christine's 402(k) in 30 years if the per annum rate of return is assumed to be 12% compounded monthly?

English
We are working on Passive and Active voice. i really dont understand it, so do you know any websites that could help me with passive and active voice.

math
i typed it in my calculator and i got : 1910 but i dont know if thats right? sorry

Math
Christine currently has $5000 in her 401(k) and plans to contribute $100 each month for the next 30 years into it. What will be the value of Christine's 402(k) in 30 years if the per annum rate of return is assumed to be 12% compounded monthly?

physics
weight = mg

physics
2.5x/25 = x/do do=25x/2.5x=10cm 1/di+1/do=1/f 1/25 + 1/10 =1/f 7/50=1/f f=50/7=7.14 cm

Physics
N=mgcosα F(fr)= μN = μmgcosα ma=F(fr)+mgsinα => ma= μmgcosα + mgsinα a=g(μcosα+sinα)=.... s=v²/2a=....

Physics
N=mgcosα ma=T-mgsinα => T=m(a+gsinα)

physics please help!
http://www.physics.utoronto.ca/~poptor/solutions05/pss4_optics.pdf

Physics
B.Electric field? A.Magnetic

Physics
index of refraction = c/v=λ(vac)/λ(substance) λ(water) =λ(air)/n=650 nm/1.33=489 nm. This is the wavelength of violet light The swimmer sees the red-orange color since our eyes detect the frequency of the light

Physics
In vacuum v(red)=v(blue)=v(green)= c=3 x10^8 m/s In glass v(red)>v(green)>v(blue)

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

Physics
Yes F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg² (!!!!)

Physics
(a) mv²/2=W(fr) =F(fr)s=μNs=μmgs s= mv²/2μmg= v²/2μg s is the same for the both cars (b) s↑ since μ↓

Physics
(a) using dynamics mgh=mv²/2 v=sqrt(2gh) (b) using kinenatics h=gt²/2 =>sqrt(2h/g) v=gt=gsqrt(2h/g)=sqrt(2gh)

science
L=10 cm, E= 200 GPa=200•10⁹ Pa σ=F/A =350 MPa =350•10⁶ Pa ε= ΔL/L Hook's law E= σ=E•ε=E•ΔL/L, ΔL= σ•L/ E =350•10⁶•10/200•10⁹ =0.0175 cm

Physics
L=0.2 m (a) mg=kx₁ L₁=L+ x₁=L+ (mg/k)=… (b) m•sqrt(g²+a²)=kx₂ L₂=L+x₂= L + m•sqrt(g²+a²)/k = …

physics
The roentgen is the quantity of radiation which liberates by ionisation 1 esu of electricity per 1 cm³ of air under normal conditions of temperature and pressure 1 electrostatic unit of charge (esu) = 3.33•10⁻¹º C 150 mR/hr =150•10⁻³/3...

physics
V=60 cm³ 500 mR/min= 500•10⁻³/60 = 8.33•10⁻³ R/s, the charge in 1 cm³ is q= 8.33•10⁻³•3.33•10⁻¹º =2.78•10⁻¹² C in chamber Q=2.78•10⁻¹²•60 =1.67&#...

Physics
The alcohol in the first arm floats on top of the denser glycerin and pressures it down distance h from the initial level. As a result, the glycerin rises by the distance h in the second arm. Due to the equilibrium condition, the point of the two liquids contact in the 1st arm...

Physics
Use T=2π•sqrt(L/g)

Physics, check my answer pls
Ans: C

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

Science ~conversions~
a= F/m=0.001/1.5•10⁻³=0.67 m/s²

Math 310 Math for Teachers
v(X)=v1 v(Y) = v2 s is the distance between A and B t is the time before the 1st meeting v1•t=120, v2•t=s-120, {(s-120)+(s-90)} =v1•6, v2•6=120+90. => v2=(120+90)/6=210/6=35 mph ----- t=120/v1 (1) 2s-210=6•v1 (2) 35•t=s-120 (3) === Substitute ...

physics
m₁v₁²/2 =qU => v₁ =sqrt(2qU/m₁) m₂v₂²/2 =qU => v₂=sqrt(2qU/m₂) v₁/v₂=sqrt(2qU/m₁)/sqrt(2qU/m₂)=sqrt(m₂/m₁) in magnetic field: ma=qvBsinα a=v²/R, α=90°, sin90...

Science
Radioactive decay law N =N₀exp(-λt)= =N₀exp(-ln2•t/T)= =20exp(-0.693•18000/6000) = 2.5 g

Physics
KE=mv²/2 = (mv)²/2m =p²/2m p=sqrt(2m•KE) = ... p=mv => v=p/m=...

Physics
Units????

pHYSICS
water: Q=cmΔT=4180•0.063•(49.7-21.2)=7505.19 J=1792.6 cal peanut: 0.59 g (or kg???) calorie content = 7505.19/0.59•10⁻³ J/kg=1792.6 /0.59•10⁻³ cal/kg =

Physics
Δt=1min/110=60/110=0.55 s FΔt=Δp= mΔv= m[v-(-v)] =2mv F=2mv/Δt =2•0.008•550/0.55 =16 N

Phyiscs
The height of the first stone is h₀=v₀²/2g=27²/2•9.8 = 37.2 m. v=v₀-gt, v=0 => the time of the upward motion is t= v₀/g =27/9.8=2.8 s. The 1st stone was falling down during t₁=5.5-2.8 = 2.7 s, when the 2nd stone started. The 1st ...

physic
v=200 km/h, v₀= 70 km/h, Angle that make v and v₀ is 45° => An angle α in cosine law is α (360°-2•45°)/2 =135° Cosine law: V=sqrt(v²+v₀²-2vv₀cos α)= =sqrt[40000+4900-2•200•70•(-0.707)]=254 ...

Physic
A₁v₁=A₂v₂ (πd₁²/4)v₁=(πd₂²/4)v₂ v₂=(d₁²/d₂²)v₁=(16d₁²/d₁²)1 m/s=16 m/s

Physics
F=ma a=F/m v=sqrt(2as)

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