Wednesday
July 23, 2014

Posts by elena


Total # Posts: 4,343

Physics
F=qvB sin12⁰ 1.8F=qvBsinφ sinφ/sin12⁰ =1.8 sinφ =sin12⁰•1.8=0.208•1.8=0.374 φ=sin⁻¹0.374=22⁰

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 =235919...

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 =23...

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

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

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

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 ...

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

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

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

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)=....

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

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=...

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 = …

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...

Physics
r1=r2=3 m

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

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)}

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

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) ...

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

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”

physics
R=ρL/A R =4ρL/πd² R₁ =4ρL/ (π4d²- πd²) =4ρL/ 3πd² R₁=R/3

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=...

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

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&...

Physics
sini/sinr=n2/n1 n2=n1(sini/sinr)=1.45(sin64.8/sin68.0)=...

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.

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. nut...

Physics
http://en.wikipedia.org/wiki/Torque

Physics
F=Rmv=140•0.0026•510/60=3.1 N

Physical Science
convection.

Physical Science
convection.

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...

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

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= ...

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

Physics
See my answer to a similar question below under related questions.

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

Physics
Work=mgh==30•9.8•250 =... Power =mgh/t=30•9.8•250/30•60 =...

physics
a(centr)= mv²/R=0.036•36²/1.31 =…

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

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

physics
ω=v/R ω =2πf v/R=2πf f=v/2πR= …

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}=...

physics
The airplanes have the same speed -true The airplanes have the same velocity-false

Physics
http://www.physlink.com/education/askexperts/ae72.cfm

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&...

PHYSICS
ΔKE=ΔPE=mgΔh=60•9.8•42 =24696 J

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

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&#...

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

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

Phyics
ΔQ =4KCal=16747.2 J ΔQ=ΔU+W ΔU=ΔQ-W =16747.2-1000=15747.2 J

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

Physics
h= vₒ²•sin²α/2•g = =L•g•sin²α/2•g•sin2α= = L•sinα/4•cos α= =L•tanα/4

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/ ...

Physics
F=mg=100•9.8=980 N

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/...

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

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

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

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 = ...

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

physics
F(hor) =Fcos45 F(vert) =Fsin45

physics
F=ILB I=F/LB

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

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

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

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

physics
http://answers.yahoo.com/question/index?qid=20090308072337AA3lVRt

Check my physics
OK

PHYSICS
mgh=mv²/2 v=sqrt(2gh)=...

PHYSICS
v(fin)=v₀=20 m/s

PHYSICS
mgh₁-mgh₂=mv²/2 h₂=h₁-v²/2

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

PHYSICS
Q=ΔKE=mv²/2

PHYSICS
F=ma=mv²/2s v=sqrt(2Fs/m)

PHYSICS
W=kx²/2

PHYSICS
mgh=mv²/2 v=sqrt(2gh)=...

physics
Q=W=F(fr)s=μNs=μ•mg•s =…

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

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

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...

Physics
h= vₒ²•sin²α/2g, Solve for vₒ

Physics
T=F/cosφ =60/0.707 = =60/0.707 = 84.87 N

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

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

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

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

physics
http://answers.yahoo.com/question/index?qid=20120417015851AAp5Qdo

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

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

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)= …

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...

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.

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

Physics
See the answer to a similar question below under related questions

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

Physics
5T=68 => T=68/5=13.6 s λ=34.1 m v= λ/T f=1/T

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