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December 20, 2014

Posts by Elena


Total # Posts: 4,338

PHYSICS
ΔQ = m•c•ΔT =1000•0.11•(95-20)=8250 cal
July 3, 2013

gen physics
a=v/t s=at²/2
July 2, 2013

Physics
PE=KE=KE(trans) +KE(rot) PE= mgh=mgLsinα KE= mv²/2 + Iω²/2= = 2 mv² /2 + 2mr²v²/5•2•r²= =0.5 mv² + 0.2 mv² =0.7 mv² mgLsinα= 0.7 mv² v =sqrt{gLsinα/0.7} = = sqrt{9.8•4•sin42⁰/0.7} =...
July 2, 2013

phy
Hook’s Law F₁=kx₁ F₂=kx₂ F₁/F₂=x₁/x₂ x₂=x₁F₂/F₁=0.4•100/80 =0.5 m
July 2, 2013

phy
242 – 22.8 =219.2 mm, 100⁰ /219.2 = 0.456 ⁰/mm, 22.8 + 0.456•20=31.92 mm.
July 2, 2013

Physics
Load = ultimate strength x Area/ Factor of safety= =630•10⁶•π•0.03²/4•5=8.9064•10⁴ N= =89.064 kN
July 2, 2013

Physics
cross sectional area has to be measured in cm² or m² => A= 5.300cm² = 5.3•10⁻⁴ m² = 0.00053 m² Factor of safety = ultimate strength/allowable strength= = ultimate strength x Area/ Load = =630•10⁶•5.3•10⁻&#...
July 2, 2013

physics
ave) = total distance/ total time =s/t t=s/v(ave) = 100/20 = 5 s s=v₀t+at²/2 ….(1) v= v₀+at a= (v -v₀)/t ….(2) Substitute (2) in (1) 2s= v₀t +vt v₀ =( 2s –vt)/t =( 200 -25•5)/5 = 15 m/s a=(v -v₀)/t =(25-15)/5 = 2 m/s...
July 2, 2013

physics
ave) = total distance/ total time =s/t t=s/v(ave) = 100/20 = 5 s s=v₀t+at²/2 ….(1) v= v₀+at a= (v -v₀)/t ….(2) Substitute (2) in (1) 2s= v₀t +vt v₀ =( 2s –vt)/t =( 200 -25•5)/5 = 15 m/s a=(v -v₀)/t =(25-15)/5 = 2 m/s...
July 2, 2013

Sciences
mg = Tsinα T=mg/sinα=0.875•9.8/sin10.5 =0.817 N mv²/R = Tcosα v=sqrt{TRcosα/m} = =sqrt{0.817•3.46cos10.5/0.875} = 1.78 m/s
July 2, 2013

General physics
a= v²/R. top ma= mg –N N=m(g-a) = =m (g- v²/R) = = 34.1{9.8 - (4.23²/9.15 )}= =267 N. bottom ma=N-mg N= m(g+a) = = m (g+ v²/R) = = 34.1{9.8 +(4.23²/9.15 )}= =401 N
July 2, 2013

general physics
a) KE=mv²/2= 13900•23.5²/2 = 3.83•10⁶ J. b) KE= PE₁+KE₁ KE₁ = KE-PE = mv²/2 -mgh₁ = =3.83•10⁶ - 13900•9.8•12.5= =3.83•10⁶- 1.7•10⁶ =2.13•10⁶ J. mv₁²/2 = KE&#...
July 2, 2013

physics
v(ave) = total distance/ total time =s/t t=s/v(ave) = 100/20 = 5 s s=v₀t+at²/2 ….(1) v= v₀+at a= (v -v₀)/t ….(2) Substitute (2) in (1) 2s= v₀t +vt v₀ =( 2s –vt)/t =( 200 -25•5)/5 = 15 m/s a=(v -v₀)/t =(25-15)/5 = 2 m...
July 2, 2013

physics
a= v²/R. top ma= mg –N N=m(g-a) = =m (g- v²/R) = = 34.1{9.8 - (4.23²/9.15 )}= =267 N. bottom ma=N-mg N= m(g+a) = = m (g+ v²/R) = = 34.1{9.8 +(4.23²/9.15 )}= =401 N
July 1, 2013

Physics
a) KE=mv²/2= 13900•23.5²/2 = 3.83•10⁶ J. b) KE= PE₁+KE₁ KE₁ = KE-PE = mv²/2 -mgh₁ = =3.83•10⁶ - 13900•9.8•12.5= =3.83•10⁶- 1.7•10⁶ =2.13•10⁶ J. mv₁²/2 = KE&#...
July 1, 2013

general physics
a) the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², r=1.74•10⁶ m M=7.35•10²² kg ma=F F =G•m•M/R² ma=mv²/R G•m•M/R² =mv²/R v=sqrt(GM/R) T=2πR/v = 2π•sqrt{R&#...
July 1, 2013

general physics
the 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. r=R+h =6.378•10⁶ +0.327•10⁶ =... ma=F F =G•m•M/r²...
July 1, 2013

physics
L=vₒ²•sin2α/g, vₒ² = Lg/sin2α F=mvₒ²/R=m Lg/Rsin2α=2259.69 N
July 1, 2013

physics
Weight =W= mg m=W/g =491 / 9.8 =50.1 kg F = mv²/ r=173.6 =50.1•4.2²/5.09 = 173.6 N since his partner is in the straight-down position, the man also has to apply force to keep his partner from falling down due to gravity, so you have to add the partner's ...
July 1, 2013

physics
W= mg=> m=W/g = 507 /9.8 = 51.7 kg. ma=T-mg a= T/m - g = =590/51.7 - 9.8 = 1.6 m/s² h=at²/2 t= sqrt(2h/a) = =sqrt(2•30.1/1.6) =6.13 s.
July 1, 2013

physics
http://answers.yahoo.com/question/index?qid=20090818145339AAdPF06
July 1, 2013

Physics
F=12 N
July 1, 2013

physics
ω=2π/T= 2π/24•3600= 7.27•10⁻⁵rad/s 1) equator v= ω•R=7.27•10⁻⁵•6.38•10⁶ = … m/s a=ω²•R= … m/s² 2) at a latitude of 76.0 ° north of the equator r=Rcos76.6⁰=6....
July 1, 2013

physics
v=at= 0.1g•3.15•10⁷=3.087•10⁷ m/s, s=at²/2=0.1g•(3.15•10⁷)²/2=4.86•10¹⁴m, s₁=d-s=4•10¹⁶-4.86•10¹⁴=3.95•10¹⁶ m, t₁=s₁/v = 3.95•10¹&#...
July 1, 2013

Physics
[Load] =N (not Pa)
July 1, 2013

physics
t=2πR/v
June 30, 2013

physics
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², F =G•m₁•m₂/R² m₁=m m₂=5.65-m F =G•m •(5.65-m)/R² Solve for m
June 30, 2013

Phyiscs
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², Earth’s mass is M = 5.98•10²⁴kg, Earth’s radius is R = 6.38•10⁶ m. T=L/v F = m₁•m₂/R= G•m•M/(2.07R) ² F=ma=m•v²...
June 30, 2013

Physics
φ=ω₀t-εt²/2 ω=ω₀-εt ω=0 ω₀=10π rad/s ε=1.2 rad/s² φ=2πN 0=ω₀-εt => t = ω₀/ε 2πN = ω₀t-εt²/2= =ω₀²/ε - ε...
June 30, 2013

Physics
T =>he first law states that if the net force (the vector sum of all forces acting on an object) is zero, then the velocity of the object is constant => 1. One force acts on the object.
June 30, 2013

Physics
f. Force acting down and constant This force is gravity - mg
June 30, 2013

Physics
F=ma=mv/t
June 30, 2013

Physics
e. Force acting down and constant (mg - gravity)
June 30, 2013

PHYSICS 2
KE=W=eU=1• 10⁴ eV
June 30, 2013

physics
1) ma=T-mg T=m(a+g) 2) a=0 => 0=T-mg T=mg
June 30, 2013

physics
mgsinα=μN=μmgcosα μ=tanα
June 30, 2013

physics
v=const => ΣF=0 F₁₂=sqrt(F₁²+F₂²) F₃=F₁₂ F₃(x)= -F₂ F₃(y)= -F₁ tan α= F₃(y)/ F₃(x)= =F₁/F₂ α is the angle that F₃ makes with +x direction (south of east)
June 30, 2013

Physics
a=v/t
June 29, 2013

physics
a=v²/2s= 5.5²/2•0.45 = … t=v/a=….
June 29, 2013

Physics (Stress & Strain)
Factor of safety = ultimate strength/allowable strength Allowable strength= ultimate strength/ Factor of safety= =550•10⁶/3=183.33•10⁶ Allowable strength=Load/Area => Load= Allowable strength x Area = = Allowable strength x (π•d²/4) =183...
June 28, 2013

Physics (Stress & Strain)
Allowable strength=Load/Area, Factor of safety = =ultimate strength/allowable strength= = ultimate strength x Area/ Load= =550•10⁶•7•10⁻⁴/79000=4.873
June 28, 2013

physics
vt/L=5.45•10³•111•10⁻³/91.4 =6.62
June 28, 2013

physics
http://www.god-and-science.com/physics/phy111/2009/eoc02/ch01_a.pdf Problem #27
June 28, 2013

physics
L=37 m v₁=5.95 m/s v₂=7.8 m/s L+ v₁t= v₂t t=L/ (v₂-v₁)= =37/(7.8-5.95) =20 s d= v₁t=5.95•20=119 m.
June 27, 2013

physics
N=5540 lines/cm=554000 lines/m d=1/N=1.8•10⁻⁶ m 1) m=2 tanφ₂= x₂/L=26/42.5 =0.61 φ₂=tan⁻¹0.61= 31.5⁰ sinφ₂=sin 31.5⁰=0.52 dsinφ =mλ dsinφ₂=2λ λ= dsinφ₂/m=1...
June 27, 2013

Physics
C=εε₀A/d ε=1 ε₀=8.85 •10⁻¹² F/m A=Cd/ ε₀= =3.78•10⁻¹²•0.303•10⁻³/8.85•10⁻¹²= =1.29•10⁻⁴ m²
June 26, 2013

Physics (Stress & Strain)
Shearing stress (tangential stress) τ=V/A, where V ia resultant shearing force which passes through the area A being sheared. V= τA=τ•πdh Shear force is equal to the punching force P P=τπdh= =670•10⁹•3.14•0.03•0.08...
June 26, 2013

Physics (Stress & Strain)
OK
June 26, 2013

Physics (Stress & Strain)
Shearing stress (tangential stress) τ=V/A, where V ia resultant shearing force which passes through the area A being sheared. V= τA=τ•πdh Shear force is equal to the punching force P P=τπdh= =670•10⁹•3.14•0.03•0.08...
June 26, 2013

astonomy
A=4πr²
June 25, 2013

physics
a=v²/2s =1.9²/2•7.8=0.23 m/s² ma=F(fr)=μN=μmg μ=a/g = 0.23/9.8=0.23
June 25, 2013

Physics
v₀⒳=v₀•cosα v₀⒴=v₀•sinα L=vₒ²•sin2α/g,
June 25, 2013

Please help how do I calculate this
Hot water lost Δ H₁=CmΔT₁ =4.180• 25•(51.5-35) =1724 J Cold water got Δ H₂=CmΔT₂ =4.180• 25•( 35-25) =1045 J Δ H = Δ H₁-Δ H₂=1724-1045=679 J heat capacity of the calorimeter (Calorimeter...
June 25, 2013

Physics
F=ma=mv²/2s
June 25, 2013

Physics
F=ma=mv/t
June 25, 2013

physics
pV=mRT/M => ρ =m/V = pM/RT => RT=pM/ ρþ U= miRT/2M = =mipM/2M ρ =mip/2 ρ= =1•5•80000/2•4 = 50000 J
June 25, 2013

Physics (Stress & Strain)
σ= F/A A=1•2.5=2.5 cm²=2.5•10⁻⁴m² σ= 150000/2.5•10⁻⁴=6•10⁸ N/m². Strain is defined as "deformation of a solid due to stress" and can be expressed as ε= σ/E, where E= Young’s ...
June 24, 2013

Physic (Stress & Strain)
L=1.9 m, A= 11 cm²= 11•10⁻⁴m² F=5450 N ΔL = 2.42 mm =2.42•10⁻³ m Stress σ= F/A = 5450/11•10⁻⁴=4.95•10⁶ N/m²= =4.95 MPa Strain ε = ΔL/L= 2.42•10⁻³/1.9 =1.27•10&#...
June 24, 2013

physics
PE=mgh
June 24, 2013

physics
http://gmanacheril.com/PHY2048/Text%20Materials/Lesson%204.4%20Conditions%20of%20Equilibrium.pdf Example #2
June 24, 2013

Physics
P₁₀₀>P₂₅ => U²/R₁₀₀ > U²/R₂₅. Since U = const => R₂₅>R₁₀₀
June 24, 2013

Physics
50/km/h=13.9 m/s m•a=N•sinα 0=N•cosα - m•g m•v²/R=N•sinα = m•g•sin α/cos α =m•g•tan α tan α = v²/gR =13.9²/9.8•59.9=0.329 α = tan⁻¹=18.19⁰
June 24, 2013

physics
a=(F-R)/m = (4500-1500)/2000=1.5 m/s^2
June 24, 2013

physics
Mv₁=mu+Mv₂ u = M(v₁-v₂)/m = = 208(27.9-20.1)/45.9 = =35.3 m/s
June 24, 2013

Physics
Work =power x time
June 23, 2013

physics
v(vert) = sqrt (2gh) = =sqrt(2•9.8•0.8)=3.96 m/s
June 23, 2013

physics
d=sqrt{(8-6)²+5²}= 5.4 m
June 23, 2013

physics
n=R/A A=R/n = 0.6/1.31=0.458 m http://www.saburchill.com/physics/chapters3/0004.html
June 23, 2013

Physics
E=F/q=0.032/0.003=10.67 V/m, E= - grad φ E=Δφ/Δx= Δφ/d => Δφ=Ed= 10.67•0.04=0.427 V. ΔPE = - Work of electric field= =-q•Δφ=-0.003•0.427= -1.28•10⁻³ J. Δφ=V. C=εε₀...
June 20, 2013

Physics
F=eE=1.6•10⁻¹⁹•2805 = 4.5•10⁻¹⁶ N
June 20, 2013

Physics
ℰ=Δφ=1378 V mv²/2=qΔφ v=sqrt(2qΔφ/m)=…
June 20, 2013

Physics
the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², F₁₂ =G•m₁•m₂/y²= ... F₃₂ =G•m₃•m₂/x²= ... F=sqrt(F₃₂²+F₁₂²)=... φ is the ...
June 20, 2013

physics
Average speed = =Total distance/ total time = = 2s/{t₁ +t₂} = = 2s/{s/v₁) +(s/v₂)} = =2v₁v₂/(v₁+v₂) = =2•30•45/(30+45) = 36 km/h
June 20, 2013

Physics (Intro)
f=ω/2π =sqrt(k/m)/ 2π f=N/t=20/5=4 Hz
June 19, 2013

physics
C=εε₀A/d ε=1 ε₀=8.85 •10⁻¹² F/m A=1•1=1 cm²=1•10⁻⁴ m² C=q/U=q/Ed ε₀A/d= q/Ed q=ε₀AE=8.85 •10⁻¹²•1•10⁻⁴•1•10⁶= =...
June 19, 2013

science
c) Pascal/s law
June 19, 2013

science
a) Uranium
June 19, 2013

science
d) Gold
June 19, 2013

science
mv=(m+M)u u=mv/(m+M) = 4•10/(4+40) = 0.9 m/s d) 1 m/s
June 19, 2013

science
a) AgNO3
June 19, 2013

science
T=0⁰C = 273 K, p= 1.01325•10⁵ Pa, M=(12+16+16) •10³ = 40•10³ kg/mol. V=mRT/Mp= = 0.004•8.31•273/44•10⁻³•1.01325•10⁵= =0.00204 m³= 2.04 L
June 19, 2013

Physics
W = m•g =G•m•M/R² g= G•M/R² the 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.
June 18, 2013

physics
PE=KE+PE₁ mgH = mv²/2 + mgR v²= 2g(H-R) at point A N=mv²/R =2mg(H-R)/R= =2•4.3 •10⁻³•9.8•(0.8-0.31)/0.31 = = 0.133 N
June 18, 2013

Physics
Δh= 13•4.47 m ΔPE =mgΔh = 86.9•9.8•13•4.47= =49487.6 J
June 18, 2013

physics
F =G•m₁•m₂/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg²,
June 18, 2013

physics
υ = 1.5 mol p= 3 atm = 303975 Pa V=7 L = 0.007 m³ R=8.31 J/mol•K T=? pV= υRT T=pV/υR= =303975•0.007/1.5•8.31=170 K
June 18, 2013

physics
the 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. r = 850000 m ma=F mv²/(R+r)= G•m•M /(R+r)² v=sqrt{G•M /(R+r...
June 18, 2013

physics
Wavelength = speed/frequency
June 18, 2013

physics
I=q/t q=Ne t=2πR/v I=Nev/2πR= =10¹¹•1.6•10⁻¹⁹•3•10⁸/2π•300 = =0.0025 A
June 18, 2013

physics
v=v₀-gt v=0 t=v₀/g=14/10=1.4 s
June 17, 2013

physics
λ= 630•10⁻⁹ m, d= ? μm = ? •10⁻⁶ m L=4 m k=1 x=? d•sin φ =k•λ sin φ=k•λ/d φ=sin⁻¹(k•λ/d) tan φ= x/L x=L•tan φ
June 17, 2013

Physics
s=v²/2a
June 17, 2013

physics
H-h= gt²/2 t=sqrt{2(H-h)/g} = =sqrt{2(51.5-12.9)/9.8}=2.8 s. v=gt =9.8•2.8=27.44 m/s h₁=12.9 – 1.6 =11.3 m h₁=vt₁+gt₁²/2 gt₁² + vt₁-h₁= 0, t₁² + 27.44t₁- 11.3 = 0, t₁² + 2.8t₁...
June 17, 2013

Physics
Δh=H-h= gt²/2 t=sqrt(2•Δh/g)= =sqrt{2• (3520-1760)/9.8}=18.95 s. s=vt=10•18.95=189.5 m
June 14, 2013

Physics
t=s/v=2300/320=7.1875 h
June 14, 2013

Physics
initial position d₀=0, The maximum height at the motion with initial velocity v₀=20 m/s is H=v₀²/2g=20²/2•9.8 = 20.4 m (!!!) H=v₀t-gt²/2, v(fin)= v₀ -gt, v(fin)=0, => 0= v₀ -gt => v₀ =gt, H=gt²-gt²/2...
June 14, 2013

Physics
Electric field on the axis of the ring at the distance ‘x’ from the center of it is E = k xq/{sqrt(R²+x²)}³ k=1/4πε₀ The test charge is in equilibrium => E₁=E₂ k x₁q₁/{sqrt(R²+x₁²)}³= =k x...
June 13, 2013

physical science
Buoyant force=Weight ρ•V₁•g = Weight V₁=x•y•z₁ ρ•x•y•z₁•g = Weight z₁=Weight/ ρ•x•y•g = =445/1000•4•3•9.8=0.0038 m =3.8 mm
June 13, 2013

physics
The second law for rotation M=Iα => α=M/I M₁/I₁=M₀/I₀ => M₁/M₀=I₁/I₀ I₁ = I₀ => M₁ = M₀ F₁x₁=F₀x₀ F₁/F₀=x₀/x₁=x₀/2x₀ =1/2
June 13, 2013

Physics
The reflectivity R represents the fraction of the incident light that is reflected at the interface R=I/I₀, where I₀ and I are the incident and reflected beams intensities respectively. If the light is normal (or perpendicular) to the interface, then R={(n₂-n...
June 13, 2013

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