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April 18, 2014

Posts by Elena


Total # Posts: 4,309

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=…

Physics
θ=29°=0.5 rad The angular displacement θ=ω•t=(v/R) •t => t=θ•R/v OA=v•t=v• θ•R/v= θ•R=0.5•3.6=1.8 m

physics
ω=ε•t ε=ω/t=100/10=10 rad/s² M=I•ε=(m•R²/2) • ε= 1•0.2²•10/2=0.5 N•m

physics
ω=ε•t ε=ω/t M=I•ε=(m•R²/2) • ε=…

physics
mg=kx k=mg/x=760/0.5•10⁻³=... mgh=mv²/2 mv²/2=kx²/2. mgh=kx²/2. x=sqrt(2mgh/k)

physics
http://www.jiskha.com/display.cgi?id=1351542188

Physics
N1=500, U1 = 120 V, U2 = 24V N2=N1•U2/U1= 500•24/120 =100

physics
mg=55.5•9.8 =...

Physics
vector m•a=vector m•g +vector F(spring) a=0 => 0=vector m•g +vector F(spring) x: 0 = m•g•sinα –k•x, x=m•g•sinα/k=6.1•9.8•sin 39°/126 =0.3 m

physics
R=4.3 m, a(τ)=8.8 m/s². a(τ)=a(c) =v²/R => v=sqrt{a(c) •R}= sqrt{a(τ) •R}= =sqrt{8.8•4.3}=6.15 m/s. v=a(τ) •t, t= v/a(τ)=6.15/8.8 =0.699 s= 0.7 s. s= a(τ) •t²/2 =8.8•0.7²/2=2.156 m.

physics
If polarized light of intensity I₀ is incident on a polarizing sheet, the intensity transmitted by the sheet depends on the angle between the polarization direction of the light and the transmission axis of the sheet, φ, via I= I₀•cos²φ. After t...

physics HELP
F=ma F=F(fr)=> ma=μmg μ=a/g

Physics
V(pool) =π•D²•h/4 V= π•d²•vt/4 π•D²•h/4= π•d²•vvt/4 t=D²vh/d²•v

Physics
Centripetal acceleration a=ω²•R=T/m R=T/m•ω² The law of conservation of angular momentum I• ω²=I₀•ω₀² ω=(I₀/I)•ω₀²=(R₀²/R²)•ω₀ R³=(m...

Physics
m=7,45 g, m1=1220 g, m2=1603 g, v=348 m/s, v1 = 0.648 m/s The law of conservation of linear momentum for the 1st collision m•v+0=m1•v1+m•u u=(m•v-m1•v1)/m = v –(m1/m)v1= 348 – (1220/7.45) •0.648 = 241.9 m/s, The law of conservation of li...

physics
What is direction of initial velocity? If v=5 m/s is downward velocity, PE+KE1=KE2 mgh+mv1²/2 =mv2²/2 v2 =sqrt(2gh+v1²)

physics
The question is.....???

phisics
m=7,45 g, m1=1220 g, m2=1603 g, v=348 m/s, v1 = 0.648 m/s The law of conservation of linear momentum for the 1st collision m•v+0=m1•v1+m•u u=(m•v-m1•v1)/m = v –(m1/m)v1= 348 – (1220/7.45) •0.648 = 241.9 m/s, The law of conservation of li...

College Physic
If the inclined plane is not frictionless, you have to know the coefficient of friction. If it is frictionless, then PE=KE=KE(transl) +KE(rot) mgh= mv²/2 + Iω²/2. I=mR²/2, ω=v/R mgh= mv²/2 + mR² v²/4 R²= = 3mv²/4 v=sqrt(4gh/3)

physics
x3=7•cos30=6.06 m, y3=7/2 =3.5 m. x=(m1•x1+m2•x2+m3•x3)/(m1+m2+m3) = =0+0+69•6.06/104 =4.022 m. y=( m1•y1+m2•y2+m3•y3)/(m1+m2+m3) = =0+21•7+69•3.5/104 =3.74 m.

physics
W=W(fr)= μ•m•g•s

Physics
The torque is M=F•cosα•L. The ball is material point => its moment of inertia is I=m•L². The Newton’s 2 law for rotation M=I•ε, F•cosα•L= m•L²•ε, ε= F•cosα•L/ m•L²=F...

physics
20.7-2.25=18.45 cm Effort x Effort-arm = Load x Load-arm Load is 18.45 29.3/2.25=…

Physics
s=v₀•t+a•t²/2 Solve for v₀

physics
R=4.3 m, a(τ)=8.8 m/s² a(τ)=a(c) =v²/R => v=sqrt{a(c) •R}= sqrt{a(τ) •R}= =sqrt{8.8•4.3}=6.15 m/s v=a(τ) •t, t= v/a(τ)=6.15/8.8 =0.699 s= 0.7 s. s= a(τ) •t²/2 =8.8•0.7²/2=2.156 m.

Physics Help, Please
m•a=F(fr)=μ(s)•m•g a= μ(s)•g

Physics
N = mg+Fsinα = 14•9.8 +200•sin37

physics
The torques: m(A) •g•2 +(m/2) •g•1 = =(m/2) •g•1+m(B) •g•2+m(C) •g•x 2{m(A)-m(B)}=m(C) •x x=2(42-26)/21 = 1.52 (meters)

physics
m1•0+m2•v2=(m1+m2)v v=m2•v2/(m1+m2)

physics
T=2•π•sqrt(l/g) T= 2•π•sqrt(m/k) sqrt(l/g) =sqrt(m/k) L/g=m/k Solve for ‚m’.

physics
Let V be the volume of the duck. Weight of displaced water = weight of the duck 0.26•V•ρ•g= mg 0.26•V•1000•g =mg 260 V = m The density of the duck is ρ= m/V= 260 V/V= 260 kg/m³ V= m/V=2.6/260=0.01 m³

physics
v₁= (m₁-m₂)v₁₀/(m₁+m₂) v₂=2m₁v₁₀ /(m₁+m₂)

Physics
2) 8.8 m/s2 m•a=F(fr)=μ(s) •m•g a= μ(s) • g

Physic
ε= ω/t=32.4/0.861=37.63 rad/s² φ=ω²/2ε=32.4²/2•37.63=13.95 rad=799.3°

Physics
Centripetal acceleration a=ω²•R=T/m R=T/m•ω² The law of conservation of angular momentum I• ω²=I₀•ω₀² ω=(I₀/I)•ω₀²=(R₀²/R²)•ω₀ R³=(m...

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