Saturday
November 22, 2014

Posts by Elena


Total # Posts: 4,334

PHYSICS help please!!!!!!!!!!
Q(gained) =Q(lost) Q(lost) =Q₁+Q₂+Q₃ Q₁ = c₁m(Δt₁)=2020•1•(120-100) = 40400 J Q₂ = Lm=2256000•1= 2256000 J Q₃=c₂m(Δt₂)=4186•1•(100-85) = 62790 J Q(lost) =40400 +2256000+62790 =...
March 31, 2013

PHYSICS help please!!!!!!!!!!
Q(gained) =Q(lost) Q(gained) =Q₁+Q₂+Q₃ Q₁ = c₁m(Δt₁)=2020•1•(120-100) = 40400 J Q₂ = Lm=2256000•1= 2256000 J Q₃=c₂m(Δt₂)=4186•1•(100-85) = 62790 J Q(gained) =40400 +2256000+62790 =...
March 31, 2013

physics
After the 1st rebounce the speed is v/2, after the 2nd rebounce – v/4, after the third rebounce –v/8, => m(v/8)²/2=mgh₁ v=sqrt(128gh₁) =141.7 m/s mv²/2=mgh h= v²/2g=141.7²/2•9.8=1024 m
March 31, 2013

math
An elementary school collected a total of 240 cans during a food drive. Grade 3 students collected 1/3 of all the cans grade 4 students collected 52 cans, and the rest of the cans were collected by grade 5 students. How many cans did grade 5 collect? A.28 B.80 C.108 D.188
March 29, 2013

physics
Assume g=10 m/s². The ball upward motion 0=v₀-gt, t=v₀/g=10/10=1 s. The train motion for time 1 s 0= v-at, a=v/t=5/1 = 5 m/s², the distance s= v t -at²/2 =5•1 -5•1²/2 = 2.5 m
March 29, 2013

Physics. LAST PROBLEM!!
A small metal ball with a mass of m = 82.5 g is attached to a string of length l = 1.72 m. It is held at an angle of θ = 58.5° with respect to the vertical. The ball is then released. When the rope is vertical, the ball collides head-on and perfectly elastically with ...
March 26, 2013

physics
y=gt²/2 t=sqrt(2y/g) =sqrt(2•920/9.8)=13.7 s
March 26, 2013

Physics
mv²/2=qU v=sqrt(2qU/m) R=mv/qB= (m/qB)• sqrt(2qU/m)= R3/R4 = sqrt{ 2Um q₄B²/q₃B²2Um)= =sqrt(q₄/q₃) sqrt(4e/3e)=1.15
March 26, 2013

Physics
T=t/N=11.8/10=1.18 s ω=2π/T=2π/1.18=5.32 rad/s T=mv²/R=mω²R=0.013•5.32 ²•0.93=0.34 N
March 25, 2013

physics
s=2.08 m m=0.592 kg R=0.0786 m a is the acceleration of the system (m1+m2) m₁a= T₁ m₂a= m₂g-T₂ Iε=M => mR²•a/2R = (T₂-T₁)R, T₂-T₁= ma/2, a= m₂g/( m₁+m₂+m/2)=... a=v²/2s v=sqrt(2as...
March 24, 2013

physics
s=2.08 m m=0.592 kg R=0.0786 m a is the acceleration of the system (m1+m2)
March 24, 2013

physics
m₁a= T₁ m₂a= m₂g-T₂ Iε=M => mR²•a/2R = (T₂-T₁)R, T₂-T₁= ma/2, a= m₂g/( m₁+m₂+m/2)=... a=v²/2s v=sqrt(2as)=... ω=v/R=...
March 24, 2013

Physics
Magnetic field of the current-carring wire at distance b from it is B=1/2πb If B=B(Earth)/3= 5•10⁻⁵/3 T, I=2πbB= 2π•0.3•5•10⁻⁵/3 = …
March 24, 2013

Physics
x=0.45 m, D=0.12 m, I= 2 A, B=2.1 kG=2100G= 0.21 T μ₀=4π•10⁻⁷ H/m B=μ₀nI = μ₀NI/x N=Bx/ μ₀I The length of the wire L=N•πD= Bx πD / μ₀I= =0.21•0.45•π•0.12/4π&#...
March 24, 2013

Physics
r1=r2=3 m
March 24, 2013

Physics
The speed is v=s/t=186/3=62 km/h <65 km/h He can arrive on time.
March 24, 2013

Physics
1. g =GM/R² g₁=GM/(R+h)² g₁/g=30/100= GM R²/(R+h)²GM => 0.3= R²/(R+h)² Solve for “h” (Earth’s radius is R = 6.378•10⁶ m) 2. mv²/(R+h)= GmM/(R+h)² v=sqrt { GM/(R+h)}
March 24, 2013

physics
Tsinα =ma Tcosα =mg tanα=a/g=3.2/9.8 = 0.33 α = 18°
March 24, 2013

Physics
E =kq/r² (a) E(x) = E₁-E₃=kq₁/r² - kq₃/r² = =9•10⁹{(1•10⁻⁶/0.23²)- (7•10⁻⁶/0.23²)}= -1.02•10⁶ V/m (b) An altitude of a triangle is h=0.46cos30=0.46•0.866=0.398 m E(y...
March 24, 2013

physics
1. Flowrate=A•v=21•0.89 = 18.69 m³/s 2. A₁v₁=A₂v₂ v₂=A₁v₁/A₂=21•0.89/17=1.1 m/s
March 22, 2013

Math/Physics
Q=55034175 J c(ice)=2060 J/kg•℃ λ=330000 J/kg c(water)=4183 J/kg•℃ Q=Q₁+Q₂+Q₃ Q=c(ice)m(12.15-0)+λm+c(water)m(t-0), Q/m=12.15•c(ice) +λ+c(water)•t. Solve for “t”
March 22, 2013

physics
R=ρL/A R =4ρL/πd² R₁ =4ρL/ (π4d²- πd²) =4ρL/ 3πd² R₁=R/3
March 21, 2013

Physics
sinα=R/L=0.3/1=0.3 α=17.45° mv²/R=Tsinα …..(1) mg=Tcosα …..(2) Divide (1) by (2) v²/Rg=tanα v=sqrt(R•g•tanα)= =sqrt(0.3•9.8•0.31)=0.27 m/s ω=v/R=0.27/0.3=0.9 rad/s f= ω/2π=0.9/2•3.14=...
March 21, 2013

physics impulse
1) p=mv=2•4= 8 kg•m/s 2) KE=mv²/2 3) At elastic collision p= - mv 4) Δp= p1-(-p2) =mv – (-mv)= 2mv 5) p(wall)= Δp=2mv 6) F•Δt=mv F= mv/ Δt
March 21, 2013

physics
We’ll use Kirchhoff’s Current Law: At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. Node: I₁, I₂ and I₁₂ currents: I₁+I₂-I₁...
March 20, 2013

Physics
sini/sinr=n2/n1 n2=n1(sini/sinr)=1.45(sin64.8/sin68.0)=...
March 20, 2013

Ecology
The effect of humans on the environment is more drastic than that of other species because people have a greater ability to 1. adapt to seasonal changes. 2. learn new skills. 3. alter the environment. 4. eat different types of food.
March 19, 2013

Biology
Eutrophication refers to 1. the concentration of a toxic substance in the tissues of organisms. 2. depletion of mineral resources as a result of leaching. 3. the warming of the earth’s surface. 4. the damage to the ozone layer that protects the earth from UV light. 5. ...
March 19, 2013

Physics
http://en.wikipedia.org/wiki/Torque
March 19, 2013

Physics
F=Rmv=140•0.0026•510/60=3.1 N
March 19, 2013

Physical Science
convection.
March 18, 2013

phical science
Neutrinos are almost massless, travel close to the speed of light, and pass through matter almost undisturbed. Photons, on the other hand, have no mass, travel at the speed of light, yet are absorbed and/or reflected even by fairly sparse matter such as gasses. A photon has an...
March 18, 2013

physics
kx²/2 = mv²/2 v=sqrt(kx²/m)=sqrt(244•16•10⁻⁴/0.099) =...
March 18, 2013

physics
v₀ = 8.9 m/s m=4.1 kg R = 0.116 m μ=0.34 === F=ma F(fr)=μmg F=F(fr) ma= μmg a= μg=0.34•9.8=3.33 m/s² The torque M=Iε=(2mR²/5)•ε M=F(fr)•R= μmgR (2mR²/5)•ε= μmgR ε= 5μmgR/2mR²...
March 18, 2013

physics
kx²/2=mgh k=2mgh/ x²= 2•0.0961•9.8•0.591/(0.04754)²=...(N/m)
March 18, 2013

Physics
See my answer to a similar question below under related questions.
March 17, 2013

Physics
L₁= μ₀N²A/x₁ => x₁=μ₀N²A/L₁ L₂= μ₀N²A/x₂ => x₂= μ₀N²A/L₂ Δx=x₂-x₁=μ₀N²A{(1/L₁)–(1/L₂)}
March 17, 2013

Physics
Work=mgh==30•9.8•250 =... Power =mgh/t=30•9.8•250/30•60 =...
March 16, 2013

physics
a(centr)= mv²/R=0.036•36²/1.31 =…
March 16, 2013

Chemistry
0.25mol of CO are mixed with 0.90mol of H2 and heated to 950 degrees celcius in a 15L flask at equilibrium 0.190mol of H2O were present, what is the concentration of the other reactants and products at equilibrium and what is Kc
March 16, 2013

Physics 1
The law of conservation of linear momentum 0=mv-MV V=mv/M= 12•7.7/76.9 =1.2 m/s S=Vt=1.2•2•60 = 144.2 m
March 14, 2013

physics
ω=v/R ω =2πf v/R=2πf f=v/2πR= …
March 14, 2013

Physics (Algerbra-based)
a(centr) = a•cosα=14.3•cos30=… a(tang)=a•sinα=14.3•sin30=… a(centr)= v²/R, v=sqrt{a(centr) •R}=...
March 14, 2013

physics
The airplanes have the same speed -true The airplanes have the same velocity-false
March 14, 2013

Physics
http://www.physlink.com/education/askexperts/ae72.cfm
March 14, 2013

physics
C=Q/V C=εε₀A/d Situation I: The capacitor is disconnected from the battery, => Q=const (a) V=Q/C=Qd/εε₀A d₁=4d=> V₁=Q/C₁=Qd₁/εε₀A=4 Qd/εε₀A=4V (b) U=CU²/2=Q²d/2εε...
March 14, 2013

PHYSICS
ΔKE=ΔPE=mgΔh=60•9.8•42 =24696 J
March 14, 2013

Physics 11th Grade
(a) cm₁(80-T)=cm₂(T-27) 2(80-T)=20(T-27) T=31.8 ℃ (b) λ= 330000 J/kg Q= λm=330000•0.1 =33000 J
March 14, 2013

Physics
Motion of the particle without deflection => F(el) = F mag) qE =qvB B=E/v=2607/6.81•10³=0.38 T For the second particle F=qE-qv₁B v₁=(F+qE)/qB= =1.8•10⁻⁹•3.72•10⁻¹²•2607}/ 3.72•10⁻¹²&#...
March 13, 2013

Physics
mv²/R=qvB R=mv/qB ΔR=R₂-R₁= =m₂v/qB - m₁v/qB= = v(m₂ - m₁)/qB)= =3•10⁵•(238-235)•1.67•10⁻²⁷/92•1.6•10⁻¹⁹•0.6= =1.7•10⁻⁴ m
March 13, 2013

Physics
ΔV=VB-VA =kq/r(B)-kq/r(A)= =kq{r(a)-r(B)}/r(A)•r(B). q = r(A)•r(B)•ΔV/k{r(a)-r(B)}= =(3.4-4.5)•45/9•10⁹•3.4•4.5 = = - 9.5•10⁻¹⁰ C
March 12, 2013

Phyics
ΔQ =4KCal=16747.2 J ΔQ=ΔU+W ΔU=ΔQ-W =16747.2-1000=15747.2 J
March 12, 2013

physics
ΔPE=A= q •Δφ Δφ= A/q=6.7•10⁻³/1.85•10⁻⁴=36 V
March 12, 2013

Physics
h= vₒ²•sin²α/2•g = =L•g•sin²α/2•g•sin2α= = L•sinα/4•cos α= =L•tanα/4
March 12, 2013

Physics
The voltage induced around the Al ring is ΔV=NΔΦ/Δt=Δ(0.5•B•A) /Δt = =0.5•A •ΔB /Δt. B =μ₀nI, ΔB /Δt= Δ(μ₀•nvI)/ Δt, ΔB /Δt= μ₀•n•ΔI...
March 12, 2013

Physics
F=mg=100•9.8=980 N
March 12, 2013

Physics
C=q/U C=εε₀A/d q=CU= εε₀AU/d A) q1= εε₀A4V/2d= 2 εε₀AV/d B) q2 = εε₀2A2V/d= 4 εε₀AV/d max C) q3 = εε₀2A V/2d= εε₀AV/d D) q4 = εε₀A V/...
March 12, 2013

Physics
KE= m•v²/2 => v²= 2•(KE)/m a=v²/2•s =2(KE)/2•m•s = KE/m•s m•a=e•E E= m•a/e = m•KE/e•m•s = KE/e•s = =250•1.6•10⁻¹⁹/1.6•10⁻¹⁹•0.2 = 1250 V/m
March 12, 2013

Physics
A) 2ma=F-2T = > a=(F-2T)/2m = (12000-2•2100)/2•700 = 5.57 m/s² s=v²/2a = 40²/2•5.57 =143.6 m. B) T₁=ma +F(fr) =700•5.57 + 2100 =5999 N
March 12, 2013

physics
Angular magnification M= - F(objective)/F(eyepiece) F(objective)=1/1.2 = 0.833 F(eyepiece) = -1/220= - 0.0045 M= 0.833/0.0045 = 185
March 12, 2013

Physics 11th grade 3
1) F=ma => a=F/m = 75/17 = 4.4 m/s² s=v²/2a=3.75²/2•4.4=1.6 m 2) p= mv=0.18•3.75 =... 3) Impulse =mv=0.18•3.75 =... 4) Q=mcΔT=2•2060•20 = ...
March 12, 2013

physics
Rate of cooling R= ΔT₁/t₁=(80-50)/5=6 degr/min t₂= ΔT₂/R=(60-30)/6=30/6=5 min
March 12, 2013

physics
F(hor) =Fcos45 F(vert) =Fsin45
March 12, 2013

physics
F=ILB I=F/LB
March 12, 2013

physics
h=gt²/2 t=2h/g=2•0.63/9.8 =0.13 s. L=vt=0.3•0.13 = 0.039 m
March 12, 2013

Physics
γ=(i+2)/i=5/3=1.67 W=νRT₁ /(γ-1)}•{1-(V₁/V₂)^(γ-1)} = ={p₁V₁/(γ-1)}•{1-(V₁/V₂)^(γ-1)} = =(330000•1.2/0.67) •(1-0.5^0.67)= =591044.8•0.37 =2.2•10⁵ J
March 10, 2013

Physics ~please help me~
1a) W1=W2 = mgh 2a) P1 > P2 , mgh/25 >mgh/35 2) W=Fs=80•10 =800 J
March 9, 2013

physics
I=(0.73/2)²(4+3+5+2) = 1.87 kg•m² M=Iε=1.87•0.63 =1.175 kg•m
March 9, 2013

physics
http://answers.yahoo.com/question/index?qid=20090308072337AA3lVRt
March 9, 2013

Check my physics
OK
March 7, 2013

PHYSICS
mgh=mv²/2 v=sqrt(2gh)=...
March 7, 2013

PHYSICS
v(fin)=v₀=20 m/s
March 7, 2013

PHYSICS
mgh₁-mgh₂=mv²/2 h₂=h₁-v²/2
March 7, 2013

PHYSICS
Simbol - Arial Unicode MS http://www.alanwood.net/unicode/fonts.html
March 7, 2013

PHYSICS
Q=ΔKE=mv²/2
March 7, 2013

PHYSICS
F=ma=mv²/2s v=sqrt(2Fs/m)
March 7, 2013

PHYSICS
W=kx²/2
March 7, 2013

PHYSICS
mgh=mv²/2 v=sqrt(2gh)=...
March 7, 2013

physics
Q=W=F(fr)s=μNs=μ•mg•s =…
March 7, 2013

physics
α=ΔL/L•ΔT α=3.6•10⁻⁵/3 ΔL = 3.6•10⁻⁵•17• (5-100)/3 = = -0.05814/3=0.01938 m
March 6, 2013

physics
α=ΔL/L•ΔT ΔL = α• L•ΔT=3.6•10⁻⁵•17• (5-100) = = -0.05814 m
March 6, 2013

physics
The time that the bullet spends in the building t=x/v(0x) =7/340 =0.02 s. The vertical displacement of the bullet in the building y= 0.56 m. The vertical component of the velocity of the bullet as it passes through the window is v(y) = (y- gt²/2)/t = y/t - gt/2= =0.5/0.02...
March 5, 2013

Physics
h= vₒ²•sin²α/2g, Solve for vₒ
March 5, 2013

Physics
T=F/cosφ =60/0.707 = =60/0.707 = 84.87 N
March 5, 2013

Physics
cos φ=15/40= 0.375 φ=68⁰ F=Tsin φ = 1000•sin68 =927 N
March 5, 2013

Physics
v₁= {+2m₂v₂₀ +(m₁-m₂)v₁₀}/(m₁+m₂) v₂={ 2m₁v₁₀ + (m₂-m₁)v₂₀}/(m₁+m₂)
March 5, 2013

Physics
L=v(x)•t => t=L/v(x) h=gt²/2 = gL²/2v(x)² v(x)= sqrt (gL²/2h)
March 5, 2013

physics
k=mg/x=2.5•9.8/0.0305 =803.3 N/m the natural frequency is ω =sqrt(k/m) = sqrt(803.3/2.5)=17.9 rad/s
March 5, 2013

physics
http://answers.yahoo.com/question/index?qid=20120417015851AAp5Qdo
March 5, 2013

physics
(a) W(grav) = 0 since there is no change in height between the initial point and point A. (b) W(grav) – mgh –mg(h/2) = mgh/2 (c) W(grav) mgh -0 = mgh (d) mgh/2 (e) mgh
March 4, 2013

Physics
I=ℇ/(R+r) R= (ℇ-Ir)/I= (7.9-0.88•1.37)/0.88 = … P=I²r = …
March 4, 2013

Physics
x=Asinωt v=dx/dt =Aω cosωt= Aω•sqrt(1-sin²ωt) = =ω•sqrt(A² - A² sin²ωt)= ω•sqrt(A² -x²) A=0.076 m x= 0.045 m ω =17.8 rad/s v= ω•sqrt(A² -x²)= …
March 4, 2013

physics
ΔKE=-ΔPE KE2-KE1= -(PE2-PE1) ΔKE= KE2-KE1= m(v/2)²/2-mv²/2= = mv²/8-mv²/2= - 3mv²/8, ΔPE= PE2-PE1= k•q1q2/r-0=ke²/r - 3mv²/8 = - ke²/r, r=8ke²/3mv²= ... k =9•10⁹ N•m²/C² e =1.6...
March 4, 2013

Physics please help!!
Kepler’s Third Law. The square of the period is proportional to the cube of the distance from the star: T²∼R³ If the distance is increased by 25, then T² is increased by 25³, which means T is increased by the sqrt(25³)=125.
March 4, 2013

Physics please help!!
http://answers.yahoo.com/question/index?qid=20091117133730AAqpbug
March 4, 2013

Physics
See the answer to a similar question below under related questions
March 3, 2013

Physics
Elongation of the spring is x=2.69 –(2.22+0.28) = 0.19 m mg= kx k=mg/x- 145/0.19=763.16 N/m
March 3, 2013

Physics
5T=68 => T=68/5=13.6 s λ=34.1 m v= λ/T f=1/T
March 3, 2013

Physics
v = sqrt(T/m₀) =sqrt(TL/m) λ =v/f => v= λf (λf)²=TL/m L=(λf)²m/T
March 3, 2013

Physics
I can't see your drawing but if there are no nods of standing wave between the ends λ =2L v = sqrt(T/m₀) λ =v/f => f=v/ λ
March 3, 2013

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