Sunday
October 23, 2016

# Posts by Elena

Total # Posts: 4,384

physics
ΔKE= ΔPE 480-200=mgh h=(480-200)/27•9.8 = 1.06 m
July 8, 2013

physics
1. W(grav) = -mgh 2. W(es) = mgh
July 8, 2013

physics
W=(F,s)=F•s•cosα = = 2350•817•cos180º= = 2350•817•(-1)= = - 1919950 J
July 8, 2013

math
9 x 8 +22 =94
July 8, 2013

Maths
h=sqrt{H²-(a/2)²} = =sqrt{15²-6²} = 13.75 cm, V=ha²/3 =13.75•12²/3=660 cm³, S= 4•(ha/2) =2•15•12 =360 cm².
July 8, 2013

Math
http://www.mathcaptain.com/algebra/simultaneous-equations.html ax +by =a-b bx-ay=a+b ax+by +(b-a) = 0 bx –ay +(-a-b) = 0 x y 1 -------------------------------- b ↘ b-a ↘ a ↘ b -a ↗ -a-b ↗ b ↗ -a x/{-ab-b²+ab-a²} = y/{b²-...
July 8, 2013

Math
AB=sqrt{(x₂-x₁)²+(y₂-y₁)²} = =sqrt{(0-(-2))²+(5-(-2)) ²} = =sqrt(4+49)=7.3 BC = sqrt{(x₃-x₂ )²+(y₃-y₂)²} = =sqrt{(3-0)²+(-1-5) ²} = =sqrt(9+36)=6.7 CA = sqrt{(x₁-x₃ )²+(y&#...
July 8, 2013

physics
a=v/t = 28/20 = 1.4 m/s^2
July 7, 2013

physics
Work= W=ΔKE= mv²/2 Power= P=W /t = mv²/2t t= mv²/2P = 1000•50²/2•100000 = =12.5 s.
July 7, 2013

physics
L=vₒ²•sin2α/g, vₒ =sqrt{Lg/ sin2α}= =sqrt{8.59•9.8/sin46º}= =10.8 m/s
July 7, 2013

physics
... if the vertical distance between the lid of the garbage can andthe runner’s point of release is 0.50m h=gt²/2 t=sqrt(2h/g)= sqrt(2•0.5/9.8) = 0.32 s s=vt= 6.2•0.32 = 2 m
July 7, 2013

Physics
a) I=mR²/2 http://cnx.org/content/m14292/latest/ b) KE= Iω²/2 http://www.dummies.com/how-to/content/how-to-calculate-rotational-kinetic-energy.html
July 7, 2013

physics
A. 100 cm B. 200 cm C. 50 cm
July 7, 2013

Physics
F=(m+M) g +F(fr)= (1000+800)9,8 + 4000 = 5440 N P=Fv = 5440•3=16320 W
July 7, 2013

physics
mv²/2=mgh h= v²/2g
July 6, 2013

Physics
(1) I=mR² ω=2π/T KE=Iω²/2 (2) PE= KE(hoop)=KE(trans) +KE(rot) = =mv²/2 + Iω²/2= = mv²/2 + mR²v²/2 R²= = mv²/2+ mv²/2 = mv² PE= KE(block) = mu²/2 => mv²=mu²/2 v²=u²/2 s=v²...
July 6, 2013

phy
Q1 the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², Radius of the Earth is 6400 000 m =6.4•10⁶ m ===Your data is incorrect!!! mg=G•m•M/R² mg`= G•m•M/(R+h)² (R+h)²/ R² = g /g`=9.8/4.9 = 2 R...
July 5, 2013

physics
C=εε₀A/d Energy =CU²/2 = εε₀A U² /2d New energy = εε₀A (2U)² /2•2d = εε₀A U² /d= Doubled iniutial energy
July 5, 2013

Thermodynamics
Q= 460000 J m = 27.300kg c = 390 J/kg t₁ = 35℃ t₂ = Final temperature in ℃ t₂ = Q/mc +t₁ = 460000/27.3•390 + 35 =43.2 +35 = 78.2℃
July 5, 2013

Thermodynamics
ΔL = αLΔT = =12•10⁻⁶•920•420=4.637 m
July 4, 2013

Physics (Thermodynamics)
Q= 460000 J m = 27.300kg c = 390 J/kg t₁ = 35℃ t₂ = Final temperature in ℃ t₂ = Q/mc +t₁ = 460000/27.3•390 + 35 =43.2 +35 = 78.2℃
July 4, 2013

physics
s=at²/2 +> a=2s/t²= =2•910⁻³/3²=2•10⁻³ m/s². m₁a=T-F(fr) -m₁gsinα, 0=m₁gcosα –N, m₂a=m₂g –T. F(fr) =μN=μm₁gcosα . m₁a=T- μm₁gcosα...
July 4, 2013

phy
η={Q(h) –Q(c)}/ Q(h) = =(2000-750)/2000=0.625 => 62.5%. W= Q(h) –Q(c) =2000-750=1250 J. P=W/t=1250/0.5 =2500 W
July 4, 2013

physics
km/h -> m/s, a=v²/2s
July 3, 2013

physics
km/h -> m/s km -> m a=v²/2s
July 3, 2013

Physics
km -> m a=v²/2s s=at²/2 t=sqrt(2s/a)
July 3, 2013

Physics
s=at²/2
July 3, 2013

Physics
s=v₀t+at²/2
July 3, 2013

physical science
Find solution in the Related Questions
July 3, 2013

physics
0.262KE=PE 0.262m₁v²/2 = m₂gh v=sqrt{2m₂gh/0.262m)= =sqrt{2•0.413•9.8•4.22/0.262•11.6} = =3.35 m/s
July 3, 2013

Physics
cross sectional area has to be measures in cm ² 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&#...
July 3, 2013

Physics
Factor of safety = Ultimate strength/Allowable strength …(1) Allowable strength =Load/Area ….(2) Substitute (2) in (1) => Factor of safety = =Ultimate strength x Area/ Load => Load = ultimate strength x Area/ Factor of safety= =630•10⁶•π&#...
July 3, 2013

Physics
630.000MPa = 630000kN ?????? Factor of safety = ultimate strength/allowable strength= = ultimate strength x Area/ Load Load = ultimate strength x Area/ Factor of safety= =630•10⁶•π•0.03²/4•5=8.9064•10⁴ N= =89.064 kN
July 3, 2013

Physics
Correct
July 3, 2013

Physics
cross sectional area of 10.000cm^2 => Area =10 cm²=10•10⁻⁴ m²=0.001 m² !!!!! Stress =Load/Area = = 5750/0.001 =5750000 Pa = = 5750 kPa Strain = ΔL/L = 2.74•10⁻³/1 = 2.74•10⁻³=0.00274
July 3, 2013

Physics
Correct
July 3, 2013

Physics
Correct
July 3, 2013

phy
Q1 p₁V₁/T₁=p₂V₂/T₂ p₁=p₂ V₁/T₁=V₂/T₂ T₁=27℃= 300K T₂=V₂T₁/V₂ =2 T₁= 600K =327 ℃ Q2 mgh=mcΔT ΔT= gh/c=10•210/4200 =0.5℃
July 3, 2013

phy
Q1 R is the resistance at 1730℃ P=U²/R = > R=U²/P = 12²/36= 4 Ohms ΔR/R₀=αΔ T (R-R₀)/R₀=αΔ T Δ T=T-T₀=1730-0 =1730 R- R₀=R₀•α•Δ T R₀=R/(1+ α•Δ T...
July 3, 2013

phy
Q1 σ=Eε F/A = E ΔL/L E= F•L/A• ΔL= 3000•0.5/0.00006•0.2•10⁻³ = 125000000000 N/m² Q2 α= ΔL/L•ΔT ΔL= α•L•ΔT= =0.00002 •0.1•70 =0.00014 m L₁=0.1+0.00014=0....
July 3, 2013

phy
Q1 ΔQ = mcΔT + mL = 2•4186•10 + 2.26•10⁶•2 = 4.6•10⁶ J initial volume V=m/ρ(water) = 2/1000 =2•10⁻³ m³ final volume = 3.3 m³ Change in volume ΔV=V(fin) – V(init) =3.3-2•10⁻³...
July 3, 2013

phy
Q1 ΔQ/Δt =- κ•A•ΔT/L = > ΔQ =- κ•A•ΔTt/L= =- 50.4•0.1•(-20) •30•60/0.02 = = 9072000 ≈9100000 J Q2 q= ΔQ/Δt =- κ•A•ΔT/L κ = - q•L/ A•ΔT = = - 4...
July 3, 2013

phy
dS= dQ/T = m•c•dT/T After integration ΔS=mc ln(T₂/T₁). The temperatures must be in Kelvins. For piece of metal ΔS₁=0.5•600•ln(293/573) =201.2 J/K. For the pool of water (T=const) dS=dQ/T = > ΔS₂ = ΔQ/T = m•...
July 3, 2013

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
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
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)
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

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