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November 23, 2014

Posts by Elena


Total # Posts: 4,334

Physics help
ma=F-F(fr) a=[F-F(fr)]/m s=at²/2
October 26, 2012

Physics
ω₀=2πn₀=2π/33.2=0.19 rad/s centripetal acceleration is a(cen) = ω₀²R=0.19²•42.2=1.52 m/s² tangential acceleration is a(tan) =ε•R =0.0542•42.2=0.12 m/s² acceleration is a=sqrt{ a(cen)²+a(tan)&#...
October 26, 2012

Physics
Man: φ =ω•t Dog: φ –π/2=ε•t²/2 ω•t= ε•t²/2 +π/2 ε•t² -2 ω•t+π=0 t={2±sqrt(4-2•3.14•0.31}/2•0.31 t1=3.74 s, t2 = 1.48 s ω(dog) = ε•t=0....
October 26, 2012

Physics
Man: φ=ω•t Dog: φ=ε•t²/2 ω•t= ε•t²/2 t=2 ω/ ε=2•0.5/0.31 =3.23 s ω(dog) = ε•t=0.31•3.23= 1 rad/s
October 26, 2012

Physics- PLEASE HELP
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.
October 25, 2012

Physics
-0.33
October 25, 2012

Physics
13.3 cm
October 25, 2012

Physics
angle of incidence = 30o angle of reflection = 60o angle between incident ray and reflected ray = 120o
October 25, 2012

physics
α=arctan(Fy/Fx)=arctan(60/40)=arctan 1.5=56.3°
October 25, 2012

Physics
y: mg=T+N x: F(fr)=T N=mg-T F(fr)= μN=μ(mg- T) = μmg-μT =T T(1+μ)= μmg T= μmg/(1+μ)=0.49•710/1.49=233.5 Newtons
October 25, 2012

Physics
2•T•sinφ=2•19.5•sin16º=10.75 N
October 25, 2012

Physics!
F(x) =F1(x) +F2(x) F(x)= 57•cos30°+57•cos60° = F(y) =F1(y) +F2(y) F(y) =57•sin30°+57•sin 60° = F=sqrt{F(x)²+F(y)²} tan θ=F(y)/F(x) F(x) =F1(x) +F2(x) +F3(x) =0 57•cos30°+57•cos60° +F3(x) =0 F(y) =F1(y) +F2(y...
October 25, 2012

Physics
Initial heights of the blocks: m1 -> H; m2 -> h Initial energy of the “two blocks” system is E1 = m1•g•H+m2•g•h When the blocks covered s=0.9 m the energy of ”two blocks+spring” system is E2= m1•g(H-s•sinα) +m1•...
October 25, 2012

Physics
0.73 Tesla
October 25, 2012

Physics
Electrons are emitted with more velocity.
October 25, 2012

Physics
The atomic number increases by one.
October 25, 2012

Physics
Both the number of emission of electrons and the maximum velocity will increase.
October 25, 2012

Physics
1.103 m
October 25, 2012

Physics URGENT! PLEASE
ΣF(x) =F1(x) +F2(x) +F3(x) =0 0+42•cos60°+F3(x) =0 F3(x) = -42•cos60°= -21 N ΣF(y) =F1(y) +F2(y) +F3(y) =0 36+42•sin60°+F3(y) =0 F3(y) =-36 -42•sin60°= -72.4 N F=sqrt{F(x)²+F(y)²} tan θ=F(y)/F(x)
October 25, 2012

Physics
F=mv²/R m=FR/ v²
October 25, 2012

Physics
(m1+m2)a=F m1+m2 =F/a m2=F/a – m1
October 25, 2012

physics
change of current
October 25, 2012

physics
h=g•t²/2 t=sqrt(2•h/g) S=v(x) •t
October 25, 2012

physics
KE=W(fr) KE = m•v²/2 W(fr) =F(fr) •s m•v²/2 =F(fr) •s F(fr)= m•v²/2•s
October 25, 2012

physics
m1=130/9.8 kg , m2=63/9.8 = m1•a=0=T-F(fr) m2•a=0= m2g-T => T=m2•g F(fr) =T =m2•g
October 25, 2012

Physics
v=2πR/t = … a= a(n) =mv²/R F=ma
October 25, 2012

High School Physics
L=vₒ²•sin2α/g, sin2α=L•g/ vₒ²=126•32.174/98²=0.42 1) 2α=25° , α=12.5° 2) 2α =25+90=115°,, α=57.5° t= 2vₒ•sinα/g=...
October 25, 2012

Physics
m₀=ρV=ρ•πD³/6 ρ =920 kg/m³, D=0.021 m
October 24, 2012

Physics
mgh =mv²/2 v²= 2gh) = 2•9.8•10 =196 m²/s² a=v²/2•s =196/2•2.7=36.3 m/s² F(fr) = ma=69•36.3 =2504.7 N
October 24, 2012

physics
KE=PE KE=mgh h=KE/mg =50/0.55•9.8 =9.28 m
October 24, 2012

Physics- Projectiles
h= vₒ²•sin²α/2g,
October 24, 2012

physics college
Forward force = T•cosα
October 24, 2012

physics
Units????
October 24, 2012

Physics
m1•g=N+T m2•g=T m1•g=N+ m2•g N=(m1-m2)g
October 24, 2012

Physics
PE=KE + W(fr) mgh =mv²/2 + F(fr)•s m•g•s•sinα =mv²/2 +μ•m•g•cosα•s Solve for μ
October 24, 2012

Physics
m1 =4.3•10^-3 kg, m2 = 22.6•10^-3 kg, h =1.4 m, L= 3.1 m., v1 =? m1 •v1 = (m1+m2) •v, v= m1 •v1 /(m1 + m2) . h =g•t²/2 => t = sqrt(2•h/g) L= v•t = v• sqrt(2•h/g), v =L/sqrt(2•h/g), m1 •v1 /(m1 + m2) = L/sqrt(2...
October 24, 2012

Physics HELP!!
F(x) =F1(x)+F2(x)+F3(x) =0+19.9 +0 =19.9 N F(y) =F1(y)+F2(y)+F3(y) =11.1+0-14=-3 N F=sqrt{F(x)^2 + F(y)^2} a=F/m tan alpha=F(y)/F(x) unknown angle =appha +90 degrees
October 24, 2012

Physics HELP!!
(a) ma=F1-F2 F2=F1-ma (b)F2=F1 (c) -ma=F1-F2 F2=F1+ma
October 24, 2012

Physics
You accidentally got the right answer. Correect solution is following: The Earth makes one revolution (2π) during 1 year => the angular displacement for 5 days is θ= 2π•5/365 = 0.086 rad. The angular velocity of the Earth is ω= θ/t = 0.086/5&#...
October 24, 2012

Physics
If your question is: If a rod is moving at a velocity equal to 1/2 the speed of light parallel to its length, what will a stationary observer observe about its length? The answer is L=L₀•sqrt{1-(v/c)²}=0.866L₀ The length of the rod will decrease.
October 24, 2012

Physics
F=ILBsinα sinα=1 B=F/IL = 2.2/2•1.5 =0.73 T
October 24, 2012

Physics
Electrons are emitted with more velocity. ε(energy of photon) = Work function + KE ε(blue)>ε(green) => KE(blue) >KE(green) => v(blue) > v(green)
October 24, 2012

Physics
The atomic number increases by one.
October 24, 2012

Physics
The atomic number increases by one.
October 24, 2012

Physics
Both the number of emission of electrons and the maximum velocity will increase
October 24, 2012

physics
(a) sin r = sini/n =sin 58°/1.6=0.53 r =32 ° α=180°-58°-32°=90° (b) δ= 58 -32 =26°
October 24, 2012

Physics
Q(t)=Q₀•exp(-t/RC) E~Q² => E=E₀•exp(-2•t/RC) 100-80=20% 0.2•E₀=E₀•exp(-2•t/R•C) ln0.2 =- 2•t/R•C t= - ln0.2• R•C/2 =- (-1.6) •60•90•10⁻⁶/2 =0.0043 s.
October 24, 2012

texas southern university
p1•V1=p2•V2 p2=p1•V1/V2
October 24, 2012

texas southern university
T=1/f
October 24, 2012

physics/light reflection
(a) sin r = sini/n =sin 58°/1.6=0.53 r =32 ° α=180°-58°-32°=90° (b) δ= 58 -32 =26°
October 24, 2012

physics
Find the solution in Related Questions
October 24, 2012

physics
m1=1.7 kg, m2 =2.4 kg, L=1.29 m. PE=KE m1•g•L=m1•v²/2 v=sqrt(2•g•L) The velocities of the bodies after elastic collision are u1=(m1-m2)v/(m1+m2), u2=2m1v1/(m1+m2) “-“ means the motion in opposite direction
October 23, 2012

PHYSICS H
http://www.physicsclassroom.com/mmedia/newtlaws/efar.cfm
October 23, 2012

Physics
v=sqrt(2gh)
October 23, 2012

Physics
units???
October 23, 2012

physicsssss
ω=sqrt(k/m) = sqrt(160/0.885) =13.45 rad/s x=A•sinωt v=A•ω•cosωt v(max) = A•ω A= v(max)/ω =0.38/13.45 =0.028 m a= - A•ω²•sinωt a(max)= A•ω²=0.028•13.45²=5.065 m/s²
October 23, 2012

physics
k=mg/x=0.625•9.8/0.16 =38.3 N/m T=2•π•sqrt(m/k) m= k•T²/4π²
October 23, 2012

Physics
v(max) = A•ω ω = v(max)/A T=2π/ω k=mg/A
October 23, 2012

Physics
y(max1) =mλL/d λ=y(max1)•d/m•L tanα=y(max1)/L λ=tanα•d/m=tan2.5°•20•10⁻⁶/1=0.873•10⁻⁶ m tanα=L •m/d=….
October 23, 2012

Physics
Frequency is inversely proportional to wavelength. Wavelength is directly proportional to speed. λ=c/f
October 23, 2012

Physics
f=c/λ=3•10⁸/10⁻⁸ =3Hz
October 23, 2012

Physics
f=c/λ=3•10⁸/10⁸ =3Hz
October 23, 2012

Physics
λ=c/f=3•10⁸/6•10¹⁴=
October 23, 2012

Physics
ultra violet region
October 23, 2012

Physics
ℰ(max) =NBAω =30•0.04•0.25•100 = 30
October 23, 2012

Physics
L=L₀•sqrt{1-(v/c)²}=0.866L₀ The length of the rod will decrease.
October 23, 2012

Physics
Jenifer is right 1/F = 1/0.2 – 1/0.125 – 1/0.4 +1/0.1429 = =5-8-2.5+7 = +1.5 F= + 0.667 m
October 23, 2012

Physics
Lens 1- F'= +200mm=+0.2 m Lens 2- F'= -125mm = - 0.125 m Lens 3- F'= -400mm =- 0.4 m Lens 4- F'= +142.9mm= +0.1429 m 1/F = 1/0.2 – 1/0.125 – 1/0.4 +1/0.1429 = =5-8-2.5+7 = -3.5 F= - 0.286 m
October 23, 2012

Physics
C=Q/(T2-T1) c=Q/m(T2-T1)
October 23, 2012

physics to be conceptualize
In an isolated system where only conservative forces cause energy changes, the kinetic energy and potential energy of the system can change, but the mechanical energy of the system cannot change. The work done by a conservative force on a particle moving between two points ...
October 23, 2012

Physics helppp
An isolated system is one in which objects inside the system are not influenced by any forces from outside the system.
October 23, 2012

Physics Please help !!
ΔU = U(x) - U(0) = ∫(6x - 12)dx Therefore, with U(0) = 23 J, we obtain by integrating U = 23 + 12x - 3x ² F = 0 when 6x - 12 = 0 Thus x = 2 m Substituting into U = 23 + 12x² - 3x , U = 35 J Using the quadratic equation find the negative and positive values...
October 23, 2012

physics
55 µm =55•10⁻⁶ m=0.000055 m=5.5 •10⁻⁷ m
October 22, 2012

physics
10.1 nm =0.0000000101=1.01•10⁻⁸ m= =1.01•10⁻ ⁵mm=1.01•10⁻ ²µm
October 22, 2012

physics
2. x = v t
October 22, 2012

Physics
F=qvBsinα sinα=1 => F=qvB F(p)=e2vB F(e) =evB F(p)/F(e) =2 ...2:1
October 22, 2012

Physics
m1+m2+m3 = 92.5 kg. m1= 0.31 kg m2+m3 =92.19 kg v=0.55 m/s v1= - 17 m/s v2=? (m1+m2+m3) •v= - m1•v1+(m2+m3) •v2 v2= {(m1+m2+m3) •v +m1•v1}/(m2+m3)=…
October 22, 2012

Physics
3/sqrt2 = 2.1 A
October 22, 2012

physics
r(x)= 13.8•cos15.5◦ r(x)= 13.8•sin15.5◦
October 22, 2012

Physics
Change of the horizontal component of the stone’s linear momentum is Δp(x) = m•v(0x) – (-mv(1x)} = m{v(ox)+v(1x)} = m{v(0) •cos15 +v1•cos12} For the boat Δp=p2-p1 = M•u – 0 = M•u. Thje law of conservation of linear momentum &#...
October 22, 2012

physics
h=v²/2g
October 22, 2012

PHYSICS
m•g=k•x₁ k= m•g/x₁=0.116•9.8/0.035= 32.5 N/m When the spring rises 5.7 cm =0.057 m and the spring is compressed to x₂=0.022 m F= k•x₂ =ma a =k•x₂ /m=32.5•0.022/0.116 =6.16 m/s²
October 22, 2012

Physics
The rope it attached to the man’s hands, and the chair he is in. So, there are two tensions pulling upward on the “child-chair” system. m=(287+223)/g=510/g, T=265 N 2T=mg +ma ma= (2T-mg)/m = =g (2•265- 510)/510= =9.8(530-510)/510= =0.38 m/s² N=...
October 22, 2012

physics help i still dont get it
sinα =2,5/sqrt{2.5²+(43/2)²} =0.116 m•g=2•T•sinα T=m•g/2•sinα =52/2•0.116 =225 N
October 22, 2012

physics help i still dont get it
sinα =2,5/sqrt{2.5²+(43/2)²} m•g=2•T•sinα T=m•g/2•sinα
October 22, 2012

physics
F(net)=sqrt(F1²+F2²) a=F(net)/m
October 22, 2012

physics
m=1500/9.8 kg F=ma =0.8•1500/9.8= …(N)
October 22, 2012

Physics
(a) v₂= 2m₁v₁₀/(m₁+m₂) =2•5.9•27.6/(5.9+17.7)=13.8 cm/s (b) KE1(fin) –KE1(init) =m₁ •v₁₀²/2 –m₁•v₁²/2=0.5•m₁ (v₁₀² –v₁²)= =0.5...
October 22, 2012

Physics
Number of turns in the primary coil is more than the number of turns in the secondary coil.
October 22, 2012

physics
m•g=k•x₁ k= m•g/x₁=0.116•9.8/0.035= 32.5 N/m When the spring rises 5.7 cm =0.057 m and the spring is compressed to x₂=0.022 m F= k•x₂ =ma a =k•x₂ /m=32.5•0.022/0.116 =6.16 m/s²
October 22, 2012

Physics
I1=U/R1=6.3 =2 A
October 22, 2012

physics need help bad
Find the answer in the Related Questions
October 22, 2012

Physics
The rope it attached to the man’s hands, and the chair he is in. So, there are two tensions pulling upward on the “child-chair” system. m=(287+223)/g=510/g, T=265 N 2Tmg ma ma= ( 2T-mg)/m = =g (2•265- 510)/510= =9.8(...
October 22, 2012

Physics
1/R(eq)=3/R R(eq)=R/3
October 22, 2012

Physics
m1•v= (m1+m2) •u u = m1•v/ (m1+m2)
October 22, 2012

physics
(a) KE= KE(transl) +KE(rot) = m•v²/2+Iω²/2= = m•v²/2+ (2mR²)• v²/5•2•R²= = m•v²/2+ mv²/5 =0.7 mv² (b) KE=PE 0.7•m•v²=mgh h= 0.7•v²/g =…
October 22, 2012

Physics
(a) L1 = M•v•R = Earth’s mass is M = 5.97•10^24 kg, R= 1.5•10^11 m (Earth-Sun) v=ω•R=2•π•n•R n=1 rev/year =1/365•24•3600 rev/s L1 = M•v•R = M•2πn•R²= …(kg•m²/s) (b) ...
October 22, 2012

Physics
ma= mg - N N=mg -ma
October 22, 2012

Physics
ma=-mg+N N=ma+mg
October 22, 2012

physics
v=v₀-at a= (v₀-v)/t s=v₀t -at²/2
October 22, 2012

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