Tuesday

September 16, 2014

September 16, 2014

Total # Posts: 4,331

**science**

Incomplete question
*December 16, 2012*

**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...
*December 16, 2012*

**Physics**

m=W/g=W1/g1 g1=g•W1/W
*December 16, 2012*

**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&#...
*December 16, 2012*

**physics**

KE2-KE1=W(fr) =F•s mv₂²/2 - mv₁²/2 = F•s Solve for F
*December 16, 2012*

**science**

Please see the Related Questions below
*December 16, 2012*

**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.
*December 16, 2012*

**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
*December 16, 2012*

**physics**

ma= F(fr)= μN =μmgcosα a= μgcosα
*December 16, 2012*

**physics**

L=Iω I(hoop) =mR² I(sol.cyl)= mR²/2 I(sol.sph) =2 mR²/5 I(hol.sph) =2 mR²/3
*December 15, 2012*

**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
*December 15, 2012*

**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....
*December 15, 2012*

**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)= …
*December 15, 2012*

**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)= …
*December 15, 2012*

**physics**

(a) p=mv km/h -> m/s !!! (b) F=ma=mv/t
*December 15, 2012*

**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...
*December 15, 2012*

**physics**

t=sqrt(2h/g) L=v• t
*December 15, 2012*

**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&#...
*December 15, 2012*

**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...
*December 15, 2012*

**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]. ...
*December 15, 2012*

**physical science**

v₁= {-2m₂v₂₀ +(m₁-m₂)v₁₀}/(m₁+m₂) v₂={ 2m₁v₁₀ - (m₂-m₁)v₂₀}/(m₁+m₂)
*December 15, 2012*

**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•...
*December 14, 2012*

**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...
*December 14, 2012*

**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&#...
*December 14, 2012*

**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.
*December 14, 2012*

**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&#...
*December 14, 2012*

**physics**

λ=4L=4•0.9=3.6 m f=v(sound)/ λ
*December 14, 2012*

**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&#...
*December 14, 2012*

**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).
*December 13, 2012*

**physics**

see the Related Questions below
*December 13, 2012*

**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...
*December 13, 2012*

**physics**

F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,
*December 13, 2012*

**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)
*December 13, 2012*

**Physics**

http://ca.answers.yahoo.com/question/index?qid=20101003132118AAicaXe
*December 13, 2012*

**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=(...
*December 13, 2012*

**Physics**

s=v₀t+at²/2, v₀= 4.5 m/s, a= 0.04 m/s², t= 12s
*December 13, 2012*

**Physics**

a=(v-v₀)/t=v/t F=ma
*December 13, 2012*

**physics**

http://ca.answers.yahoo.com/question/index?qid=20110714100031AAk4Hfp
*December 13, 2012*

**Physics**

Find answer in the Related Questions
*December 12, 2012*

**Physics**

C=q/U =Ne/U , N=CU/e=55•10⁻ ¹²•5.3/1.6•10⁻ ¹⁹ =1.82•10⁹
*December 12, 2012*

**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
*December 12, 2012*

**Physics**

A) 141.5 Hz
*December 12, 2012*

**physics**

From similar triangles: Hi/di =Ho/do => Hi/Ho=di/do =M
*December 12, 2012*

**physics**

mgh =179 m=179/mg =179/0.296•9.8 = 61.7 kg
*December 12, 2012*

**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⁻...
*December 12, 2012*

**physics**

PE=kx²/2 k=2•PE/ x²= =2•2.5/0.15²=222 N/m
*December 12, 2012*

**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
*December 12, 2012*

**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&#...
*December 12, 2012*

**Physics**

F(fr)=μ•N=μ•m•g•cosα
*December 11, 2012*

**Physics**

F(fr)=μ•N=μ•m•g μ=F(fr)/mg
*December 11, 2012*

**Science**

The most common mineral of the Earth's continents is quartz, the mineral SiO2.
*December 11, 2012*

**science**

http://en.wikipedia.org/wiki/Ion
*December 11, 2012*

**science**

http://en.wikipedia.org/wiki/Isotope
*December 11, 2012*

**science**

http://www.chem4kids.com/files/elem_pertable.html http://en.wikipedia.org/wiki/Periodic_table
*December 11, 2012*

**science**

http://www.chem4kids.com/files/atom_bonds.html
*December 11, 2012*

**Science**

http://www.chem4kids.com/files/atom_electron.html
*December 11, 2012*

**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...
*December 11, 2012*

**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...
*December 10, 2012*

**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?
*December 10, 2012*

**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.
*December 10, 2012*

**math**

i typed it in my calculator and i got : 1910 but i dont know if thats right? sorry
*December 10, 2012*

**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?
*December 10, 2012*

**physics**

weight = mg
*December 10, 2012*

**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
*December 9, 2012*

**Physics**

N=mgcosα F(fr)= μN = μmgcosα ma=F(fr)+mgsinα => ma= μmgcosα + mgsinα a=g(μcosα+sinα)=.... s=v²/2a=....
*December 8, 2012*

**Physics**

N=mgcosα ma=T-mgsinα => T=m(a+gsinα)
*December 8, 2012*

**physics please help!**

http://www.physics.utoronto.ca/~poptor/solutions05/pss4_optics.pdf
*December 8, 2012*

**Physics**

B.Electric field? A.Magnetic
*December 8, 2012*

**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
*December 8, 2012*

**Physics**

In vacuum v(red)=v(blue)=v(green)= c=3 x10^8 m/s In glass v(red)>v(green)>v(blue)
*December 8, 2012*

**Physics**

F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,
*December 8, 2012*

**Physics**

Yes F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg² (!!!!)
*December 8, 2012*

**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↓
*December 8, 2012*

**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)
*December 8, 2012*

**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
*December 8, 2012*

**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 = …
*December 8, 2012*

**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/...
*December 8, 2012*

**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&#...
*December 8, 2012*

**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...
*December 7, 2012*

**Physics**

Use T=2π•sqrt(L/g)
*December 7, 2012*

**Physics, check my answer pls**

Ans: C
*December 6, 2012*

**Physics**

F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,
*December 6, 2012*

**Science ~conversions~**

a= F/m=0.001/1.5•10⁻³=0.67 m/s²
*December 5, 2012*

**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...
*December 5, 2012*

**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...
*December 5, 2012*

**Science**

Radioactive decay law N =N₀exp(-λt)= =N₀exp(-ln2•t/T)= =20exp(-0.693•18000/6000) = 2.5 g
*December 5, 2012*

**Physics**

KE=mv²/2 = (mv)²/2m =p²/2m p=sqrt(2m•KE) = ... p=mv => v=p/m=...
*December 5, 2012*

**Physics**

Units????
*December 5, 2012*

**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 =
*December 5, 2012*

**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
*December 5, 2012*

**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 ...
*December 5, 2012*

**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 ...
*December 5, 2012*

**Physic**

A₁v₁=A₂v₂ (πd₁²/4)v₁=(πd₂²/4)v₂ v₂=(d₁²/d₂²)v₁=(16d₁²/d₁²)1 m/s=16 m/s
*December 5, 2012*

**Physics**

F=ma a=F/m v=sqrt(2as)
*December 5, 2012*

**Physics**

a=F/(m1+m2+m3)
*December 5, 2012*

**Physics**

mgh=mv₀²/2 v₀=sqrt(2gh)=sqrt(2•9.8•10.4)=14.28 m/s v= v₀-at, v=0 => a= v₀/t = 14.28/3.58 =4 m/s² F=ma=68.2•4=272.8 N
*December 5, 2012*

**Physics- PLEASE HELP**

v =331sqrt(T/273) v1=331sqrt(300/273) =347 m/s v2=331sqrt(313/273) =354 m/s Fundamental frequency λ=4L f=v/ λ => f1/f2 =v2/v1 => f2=f1(v2/v1)=715(354/347)=729 Hz f(beat) =f2-f1= 729-715 =14 Hz
*December 5, 2012*

**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*

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