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July 23, 2014

Posts by Elena


Total # Posts: 4,343

Physics
-F1+F2•cos α=-23 +33.8•cos39°= 3.27 N

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)] Sol...

Physics
mv²/2=mgh h= v²/2g

PHYSICS
c = e > a > d > b

physics
M/m=1

Physics
The law of conservation of linear momentum for inelastic collision m1•v1 - m2•v2=(m1+m2)•u u= {m1•v1 - m2•v2}/(m1+m2)= ={0.241•1.53 -0.321•2.49)/(0.241+0.321)= =-0.766 m/s. (in the direction of the second pizza motion)

Physics
Cosine Law u=sqrt(V²+v²-2•V•v•cos135°)= =sqrt(200²+90²-2•200•90•cos135°)= =sqrt(40000+8100 +25455.8)=271 km/h s=u•t=271•3=813 km Sine Law 271/sin135°=90/sinβ sinβ=90•sin135°/271=0.235 &#...

Physics
(a) Centripetal (or normal) acceleration is a(c)= m•v²/R=… (b) Tangential acceleration a(τ)= 1 m/s² a=sqrt{a(c)² +a(τ)²}=... (c)tanα= a(c)/a(τ)= ..

physics
ω=2π/T=2•3.14/7•10⁻⁵=… x(max) =A. v(max)=Aω => A= v(max)/ω=…

Physics
The mass of gravel is m2=441•2.67 = 1177.47 kg The law of conservation of linear momentum m1•v1= (m1+m2)v2 v2= m1•v1/(m1+m2) = =2150•2.29/(2150+1177.47)=1.48 m/s

Physics
c)

Physics
m1•v1 =(m1+m2)v v= m1•v1/m1+m2)

Physics
h₁=40 m, h₂=5m, v₁=15 m/s PE1+KE1 =PE2+KE2 mgh₁+mv₁²/2= mgh₂+ mv₂²/2 Solve for v₂

Physics
(a) Centripetal (or normal) acceleration is a(c)= m•v²/R=… (b) Tangential acceleration a(τ)= 1 m/s² a=sqrt{a(c)² +a(τ)²}=... (c)tanα= a(c)/a(τ)= ..

Physics
Find the solution in Related Questions

Physics
Δp=FΔt Δp= mv₂-(-mv₁)= m(v₂+v₁), m(v₂+v₁)=FΔt F= m(v₂+v₁)/Δt= =0.148•(10.1+8.95)/10.1•10⁻³=132.6 N

physics
λ=v/f f= v/λ

physics 209
s=at²/2 => a=2s/t²=2•0.4/2²=0.2 m/s² The equation of the load motion ma=mg-T => T=m(g-a) The equation of the pulley motion Iε=M-M(fr) M(fr) = M-Iε = TR-Ia/R= =m(g-a)R – Ia/R = ...

physics, university
m=0.05 kg, ρ =11•10⁻⁸ Ω/m d=7860 kg/m³ R=1.5Ω R= ρ•L/A d=m/V=m/A•L R/d= ρ•L²•A/A•m = ρ•L²/m. L=sqrt{m•R/ρ•}=… A= ρ•L/R = … A=πD²/4 D=sqrt(4A...

physics, university
J=nev, where J is the current density, n is free electron density, e=1.6•10⁻¹⁹C , drift velocity v= 2.98•10⁻⁴ m/s J=U/RA, where U=10 V, R=0.2 Ω, A= πr² n•e•v= U/R•π•r² n= U/R•π•r...

Physics
h₁=40 m, h₂=5m, v₁=15 m/s PE1+KE1 =PE2+KE2 mgh₁+mv ₁²= mgh₂+ mv₂²/2 Solve for v₂

Physics
m1•v1 =(m1+m2)v v= m1•v1/m1+m2)

Physics
P =mgh/t, t=20 min =1200 s

physics
λ=v/f=s/tf=2.5/1.7•3=0.49 m

Physics
m•a=F(fr) m•v²/R=μ•m•g v=sqrt(μ•R•g)

Physics
Flows to the Earth ΔS(E)=1000/290 =3.448 J/K Flows out of the Sun ΔS(S)=-1000/5700 =- 0.1754J/K ΔS= ΔS(E)+ ΔS(S)= 3.448-0.1754=3.2726 J/K

Physics
(3500-2500)•30/4100=7.32 pounds

Physics
Coefficient of performance = energy removed from fridge / ( total energy expelled – energy removed from fridge ) k=Q1/(Q-Q1) Q=Q1(k+1)/k=2.4•10⁴•5/4=3•10⁴ J

Physics
η =1 –T(cold)/T(hot) = = 1- (273+18)/(273+22) = =1-291/493 = 0.41

Physics
Thermal E~kT, where k is the Boltzmann constant, T is the temperature in Kelvins 5℃=278K Answ. 278 x 2=556 K

Physics HELP!
(a) Compare x = (7.1 cm) sin (2.1π t) with x=Asin(ωt) Then ω= 2.1π, => T=2π/ ω = = 2 π/2.1π=0.7 rad/s (b) f=1/T=1.42 Hz (c) A=7.1 cm (d) x=Asin(ωt) 2.6 = 7.1 sin (2.1π t) sin (2.1π t) =2.6/7.1=0.366 (2.1π t)=sin...

Physics URGENT!!!
k=F/Δx=8.4/0.0214 = 393 N/m ω= sqrt(393/1.3)=302.3 rad/s ω=2πf f= ω/2π=302.3/2•3.14 =48.14 Hz

Physics
b) False

Physics
Δ=2bn-λ/2 = 2k(λ/2) 2bn =(2k+1)λ/2 λ=4bn/(2k+1) For k=0, λ=4bn=4•1.25•10⁻⁷•1.38=6.9•10⁻⁷m= =6.9•10⁻⁵cm ============= λ=3mm=3•10⁻³m v=340 m/s f=v/ λ=340/3•1...

physics
(a) At the point D ma=mg mv²/r=mg v=sqrt(g•r)=sqrt(9.8•2.87)=5.3 m/s (b) KE(C)=PE+KE= =mg•2r+mv²/2= =m(2gr+5.3²/2)=54.8 J. (c) KE(B)=KE(C) + W(fr)= = KE(C) + μ•mg•s= =54.8+0.29•0.78•9.8•4.08= =63.8 J (d) PE1=KE(B) mgh...

Physics
Problem#62 http://www.physics.umn.edu/classes/2012/fall/Phys%201401V.001/downloads/169171-Ch09_ISM.pdf

physics
(a) ma=mgsinα sinα=a/g=5/9.8 =0.51 α=30.7° (b) s=at²/2 t=sqrt(2s/a)=... (c) the same acceleration

physics
KE=mv²/2

Physics. Please please help!
Δφ=φ₁-φ₂=kQ/r₁-kQ/r₂= =kQ(r₂-r₁)/r₁•r₂= =9•10⁹•4.5•10⁻⁶•8•10⁻²/20•10⁻⁴=1.62•10⁶ V mv²/2= q•Δφ, v= sqrt...

physics
n₀= 9.80 101 rev/min =….rev/s ε=2 rad/s² 2•π•n=2•π•n₀ - ε•t, since n=0, 2•π•n₀ - ε•t=0, t=2•π•n₀/ ε=… φ=2•π•n₀•t- ...

Physics
W=(F,s)=F•s•cosα = =8740•1130•cos180º= =8740•1130•(-1)= = -9876200 J

Physics HW Help, Please
mg=76300 N, m=76300/9.8 kg, s= 418 m, v₀=66.5 mph =29.7 m/s v=28.9 mph=12.2 m/s, h=10.7 m KE1-KE2= W(dr)+ PE m•v₀²/2 - m•v²/2= F(dr) •s +m•g•h Solve for “F(dr)” Answer this Question

Physics
The amplitude at resonance (ω₁ = ω₀) ia Ar =F₀/b•ω₀, A/Ar=A/( F₀/b•ω₀)= { b•ω₀/m}/sqrt{( ω₁²- ω₀²)²+(b²•ω₁²/m²)}= =1/sqrt{(m...

Physics
hole d=0.09 m ball D=d+Δd=d+10⁻⁵m=0.09001 m t=27.3℃ ΔL=αLΔT D+ΔD = d+Δd D+ α1•D•ΔT =d + α2•d•ΔT D-d = α2•d•ΔT - α1•D•ΔT= ΔT(α2•d- ^...

physics, help!!
q = Ne=- (8.2•10⁹•1.6•10⁻ ¹⁹)= =- 1.36•10⁻⁹ C. q(sph)+q =4•10⁻⁹ - 1.36•10⁻⁹ = + 2.64•10⁻⁹ C

Physics
The drops begin to move with horizontal speed v(x)=2•π•n•R=2•π•N•R/t= =2•π•22•0.5/44=1.57 m/s The time for falling down is t=sqrt(2h/g) = sqrt(2•1.5/9.8)=0.55 s. L=v(x) •t =1.57•0.55 =0.87 m

Physics
Change in velocity vecorΔv =vecor v₂-vecorv₁

Physics
Change in velocity Δv⃗=v⃗₂-v⃗₁ |Δv|=sqrt(v²+v²-2v•v•cos60°)=sqrt(2v²(1-cos60°))= =sqrt{2•60(1-0.5)}=7.74 m/s The distance covered by the car is s= 2•π•R•60°/360°=2•&#...

Physics
F=ma=mv²/R = =9.1•10⁻³¹• (2.3•10⁶ )²/ 5.1•10⁻¹¹= =9.45•10⁻⁸ N

Physics
http://answers.yahoo.com/question/index?qid=20090929074248AA1Q7sZ

physics URGENT! HELP
v₀ =21.82 mi/h, H= 1.60 x 102 ft. Upward motion h=v₀²/2g Downward motion H+h=v²/2g. v=sqrt{2g(H+h)}

physics
v₀ =21.82 mi/h, H= 1.60 x 102 ft. Upward motion h=v₀²/2g Downward motion H+h=v²/2g. v=sqrt{2g(H+h)}

Physics
a1=ω²•R1 a2=ω²•R2 a1/a2= R1/R2 a2=a1•R2/R1

physics
T=2•π•r/v=2•π•sqrt(r³/GM) T²=4π²r³/GM, r=cuberoot{GMT²/4π²}=.... v=sqrt(GM/r)=.....

physics
a=4.7g =v²/R v=sqrt(4.7•9.8•15)=26.3 m/s

physics
φ=90°=π/2 ω= φ/t a= ω²R= φ²R/t²=π²•0.59/0.31²=60.6 m/s²

physics
I1=m1•r² I2=m2•r² I3=m3•r²

Physics HELP!
M= m•g•L•sinα=7.4•9.8•2.1•sin3°=7.97 N•m

Physics
Before collision PE=KE m•g•h =m•v²/2 v=sqrt(2•g•h)= v₁₀=v₂₀=sqrt(2•9.8•5.8)=10.7 m/s (b) After collision v₁= {-2m₂•v₂₀ +(m₁-m₂)•v₁₀}/(m₁+m₂)= =...

Physics
When the objects are moving in opposite directions v₁= {-2m₂•v₂₀ +(m₁-m₂)•v₁₀}/(m₁+m₂) v₂={ 2m₁•v₁₀ - (m₂-m₁)•v₂₀}/(m₁+m₂)

Physics
On the Earth mg=GmM/R² In the spacecraft mg'=GmM/(5R)²= {GmM/R²}/25=mg/25 His weight is 50.0/25 =2.0 N

Physics
tan α=ma₁/mg = (mv₁²/r)/mg= v₁²/rg tan β=ma₂/mg = (mv₂²/r)/mg= v₂²/rg tan α/ tan β= v₁²/v₂² v₂ = v₁•sqrt(tan β/tan α)=18.5•sqrt(tan16/tan11)= =22.4...

physics
Q=c•m•ΔT For brass c= 385 J/kg•K ΔT= Q/c•m=760/385•1=1.97º

physics
Q=c•m•ΔT For brass c= 385 J/kg•K ΔT= Q/c•m=760/385•1=1.97º

physics
KE of the objects transforms into PE, and then PE→KE => v(start) =v(land)

Physics
F(fr) =2•μ•N=m•v²/R R= m•v²/2•μ•N=6•10⁻³•17²/2•0.73•1.8 = …

Physics Help!
β = ΔV/V•ΔT β =10•10⁻⁴(1/℃) ΔV=β•V•ΔT=10•10⁻⁴43.3•10⁻³•(34.5-14.5)=8.66•10⁻⁴ m³=0.866 liter.

Physics Help!
Linear expansion coefficient α=ΔL/L•ΔT For steel α =12•10⁻⁶ (1/℃) ΔL=α• L •ΔT= =12•10⁻⁶•514•(32.7+20.3)=0.327 m

physics
r= v²/a

Physics B
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², R= 0.241 m F13= G•m1•m3/R² F23= G•m2•m3/R² F23-F13= =G •m3• (m2-m1)/R²= =6.67•10⁻¹¹•41.1&#...

Physics
T=2•π•r/v=2•π•sqrt(r³/GM) T1=T2

physics
T2=mg/sin52 =57/0.788=72.3 N T1 = T2cos52=72.3•0.616= 44.5 N

physics
F(fr) =μ(s) •m•g•cosα

physics
T=F(fr) =μ(s) •m•g

physics
0=v₀-at a=v₀/t s=at²/2

physics
v=at

Physics B
F =G•m1•m2/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², R= 0.241 m F13= G•m1•m3/R² F23= G•m2•m3/R² F23-F13= =G •m3• (m2-m1)/R²= =6.67•10⁻¹¹•41.1&#...

physics
a=(v-v₀)/t=- 42/0.014=3000 m/s²

Physics- PLEASE HELP
http://www.mathematische-basteleien.de/ladder.htm Problem #7

Physics- PLEASE HELP
L•sinθ

physics
vector T +vector mg +vector F(el) =0 x: -T+F(el)cos37 =0 y: Fsin37 –mg =0 F(el) =qE q•E•cos37 = T q•E •sin37 =mg tan37 =mg/T T=mg/tan37= ... E=T/q•cos37=...

physics
(a) T= m1•g + F(el)= m1•g+ k•q1•q2/r²= =7.5•10⁻³•9.8 + 9•10⁹•32•10⁻⁹•58•10⁻⁹/0.02²=… (b) T1= m1•g + F(el)= m1•g+ k•q1•q2/r1²= T1=0.18 N. Solv...

Physics
T1=m1•a=1•7.885 = 7.885 N

Physics
For m1: m1•a=T1 (block m1=1 kg is on the surface ) For m2: m2•a=m2•g – T2 (m2=9 kg) For pulley: I•ε = M => I•a/R= (T2-T1)R => (T2-T1) = I•a/R² a(m1+m2+ I/R²)=m2•g a= m2•g/(m1+m2+ I/R²) =9•9.8/{1+9+(0.3...

Physics
For m1: m1•a=T1 For m2: m2•a=m2•g – T2 For pulley: I•ε = M => I•a/R= (T2-T1)R => (T2-T1) = I•a/R² a(m1+m2+ I/R²)=m2•g a= m2•g/(m1+m2+ I/R²) T1= m1•m2•g/(m1+m2+ I/R²) T2 = m2•g -m2•...

Physics HELP!
http://www.physics.umd.edu/~richman/phys141/hw8.pdf

Physics HELP!
The law of conservation of angular momentum I₁•ω₁ = I₂•ω₂ I₁ =mR²/2, ω₁ = 5.1 rad/s I₂ = mR²/2 +m₀•r². ω₂ = ? (mR²/2) • ω₁=(mR²/2 +m₀•r&...

Physics HELP!
The law of conservation of angular momentum I₁•ω₁ = I₂•ω₂ I₁ =mR²/2, ω₁ = 5.1 rad/s I₂ = mR²/2 +m₀•R². ω₂ = ? (mR²/2) • ω₁=(mR²/2 +m₀•R&...

Physics- PLEASE HELP
KE(tr) =m•v²/2, KE(rot) = I•ω²/2 =m•R²•v²/2•2• R²=m•v²/4. KE= KE(tr)+ KE(rot)= =m•v²/2 + m•v²/4= 3• m•v²/4.

Physics
M = I•ε I=M/ε

Physics- Elena please help!
Nnewton’s 2 Law for rotation M = I•ε, where angular acceleration ε=0.87 rad/s², the torque M = F•R , the moment of inertia I=mR²/2 , F•R= m•R²•ε/2, m=2•F/R•ε=2•180/0.45•0.87=919.54 kg I=mR...

Physics- Elena please help!
x=(m1•x1+m2•x2+m3•x3+m4•x4)/(m1+m2+m3+m4) = 0+0+3•4+5•x4/ 22 = 0 y=( m1•y1+m2•y2+m3•y3+m4•y4)/(m1+m2+m3+m4) = 0+3•5+0+5•y4/22 =0 12+5•x4 = 0 => x4 = - 2.4 m 15+5•y4 =0 => y4= - 3 m

physical science
ΔPE=KE mgΔh=mv²/2 v=sqrt(2gΔh) (a) Δh=5 m, (b) Δh=7.5 m.

Physics
You must know the directions of the forces

help one question
moonquakes. http://www.wcskids.net/grissom/staff_websites/fleming/Textbook%20pdfs/Space%20text%20pdfs/Chapter%207%20-%20Earth,%20Moon,%20Sun%20System.pdf

physics
Electric flux through the sphere with the point charge in its center is Φ = q/ε₀, the area of this sphere is A = 4πr². If the area of the spherical segment is A1=2πr(r-h) Then, from the proportion: q/ε₀ ….. 4πr². Φ1...

science
V=mass/density

Physics... URGENT !!!!
mg=66700 N, m=66700/9.8 kg, s= 418 m, v ₀=66.5 mph =29.7 m/s v=28.9 mph=12.9 m/s, h=13.1 m KE1-KE2= W(dr)+ PE m•v₀²/2 - m•v²/2= F(dr) •s +m•g•h Solve for “F(dr)”

physics
F= m•v²/R

Physics
(a) ω=2π/24•3600 rad/s v= ω•R=... a=ω²R=… (b) r=R•cos42° v1= ω•r=... a1=ω²r=…

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