# Posts by Elena

Total # Posts: 4,389

physics mechanical energy and power
P(i)=F(d) •v =300 •30=9000 W=12.07 hp P=[P(d)+mgsinα] •v= =(300+1850•9.8•sin12) •30 = =18231.3 W=24.45 hp

physics mechanical energy
W(fr)=PE-KE = mgh - mv²/2 W(fr) =F(fr) •s=F(fr)•h/sinα KE=W(fr)₁ mv²/2 =F(fr)₁ •s₁ F(fr)₁= mv²/2•s₁

physics
mv²/2= mgh h= v²/2g = 16²/2•1.62 =79 m

Physics
v=gt t=v/g =20/9.8 =2.04 s h=gt²/2 =9.8•2.04²/2 =20.4 m h=(v²-v₀²)/2g v=sqrt{2gh+ v₀²} =sqrt{2•9.8•20.4 +20²}= =28.3 m/s

Physics
(1) x₁=11.8-9.8 = 2 cm V=kx₁²/2 2.2V =kx₂²/2 2.2V/V = 2kx₁²/2 kx₂² 2.2= x₁²/ x₂² x=sqrt{2.2•2²} =2.97 cm L=9.8+2.97 =12.77 cm (2) x=sqrt{2.3•2²} =3.03 cm L=9.8-3.03=6.77 cm

Physics
x: mgsinα = F(fr) y: N=mgcosα + F mgsinα = F(fr) =μN =μ(mgcosα + F), F =mgsinα/μ - mgcosα = =mg(sinα/μ – cosα)

physics
âsin53/sin 90 = n/n(gl) n=n(gl) •sin53=1.47•0.8=1.17

Physics/Electricity
http://answers.yahoo.com/question/index?qid=20120314175225AAwIJ7M

Physics/electricity
T= 2πR/v, I=e/T=ev/2πR= =1.6•10⁻¹⁹•5.48•10⁵/2•π•2.12•10⁻¹º= =6.58•10⁻⁵A

Physics/electricity
resistivity at 20℃ is ρ=22•10⁻⁸ Ohm•m R= ρL/A= 4ρL/πD²= =2•22•10⁻⁸•19/ π(1.024•10⁻³)²= =5.076 Ohms

Physics
q =E/U =0.1/19•10⁶ =5.26•10⁻⁹ C

Physics
http://www.physics.brocku.ca/Courses/1P22_DAgostino/samples/Ch21P.pdf SP37 page 24

physical science
mgh/2=mcΔT For iron c=444 J/kg•K ΔT=gh/2c = 9.8•90/444•2=0.99℃

college physics
E=k2λ/r E=9•10⁹•2•87•10⁻⁶/2•0.1 =... E=9•10⁹•2•87•10⁻⁶/2•0.26 =... E=9•10⁹•2•87•10⁻⁶/2•1.4 =...

physics
The time to rich the highest point is tₒ= 2vₒ•sinα/2g =2•20•sin35/2•10 =1.15 s The time for covering the distance to the wall ‚d’ is t₁=d/vₒ•cosα =15/20•cos35= 0.92 s At horizontal distance d from the ...

physics
v⒳=v₀•cosα=10.02m/s v⒴=v₀•sinα=29.44 m/s a(x)=0 a(y)= -g

Physics
v=0.197m/s (?!?!) => t=s/v =5000/0.197 =25381 s=7.05 h (?!?!)

PHYSICS
The time to rich the highest point is tₒ= 2vₒ•sinα/2g =2•20•sin35/2•10 =1.15 s The time for covering the distance to the wall ‚d’ is t₁=d/vₒ•cosα =15/20•cos35= 0.92 s At horizontal distance d from the ...

physics(help)
The time to rich the highest point is tₒ= 2vₒ•sinα/2g =2•20•sin35/2•10 =1.15 s The time for covering the distance to the wall ‚d’ is t₁=d/vₒ•cosα =15/20•cos35= 0.92 s At horizontal distance d from the ...

PHYSICS
E=σ/2ε₀=2.05•10⁻⁶/2•8.85•10⁻¹²=1.16•10⁵

Physics
The time to rich the highest point is tₒ= 2vₒ•sinα/2g =2•20•sin35/2•10 =1.15 s The time for covering the distance to the wall ‚d’ is t₁=d/vₒ•cosα =15/20•cos35= 0.92 s At horizontal distance d from the ...

physics
The time to rich the highest point is tₒ= 2vₒ•sinα/2g =2•20•sin35/2•10 =1.15 s The time for covering the distance to the wall ‚d’ is t₁=d/vₒ•cosα =15/20•cos35= 0.92 s At horizontal distance d from the ...

physics
θ=θ(max) •sin(ωt+α) dθ/dt =θ(max) •ω•sin(ωt+α) (dθ/dt)(max) = θ(max)•ω= θ(max)√(g/L) v(max) =(dθ/dt)(max) •L = L•θ(max)√(g/L)

Physics
R=0.5 m W= mg mg =F(buoyant) W = (1/2) •(4πR³/3) •ρ•g = =1000•4π•0.5³•10/2•3= =2618 N

physics
ma=T-mg a=(T/m)-g= 19.5 – 9.8 = 9.7 m/s² h=at²/2=> t=2h/a = 2•10/9.7 = 2.06 s.

physics
F=ma=mv/t =12.3•10⁻⁶•4/1•10⁻³ =49.2•10⁻³ N F/mg = 49.2•10⁻³/12.3•10⁻⁶•9.8 =408.2

physics
r =(0.020m/s³)t ³ i ^ +(2.2m/s)tj ^ −(0.060m/s² )t²k ^. v= dr/dt =(3•0.020m/s³ ) •t²• i ^ +(2.2m/s) • j ^ −2• (0.060m/s² )t•k ^. a=d²r/dt²=(6•0.020m/s ³) •t i ^ -2• (0....

physics
The ball moves in projectile motion. When it is moving horizontally, v(y) =0 +x is directed to the right, +y is directed upward, a(x)= 0, a(y) =-g v₀(y)=sqrt(2gh) = sqrt(2•9.8•4) = 8.85 m/s v= v₀(y)-gt At the top point v=0 => t= v₀(y)/g =8.85/9.8...

Physics
v(x) =v₀(x) = 50 m/s v₀=84 m/s cosα =v₀(x)/ v₀=50/84 =0.6 α=53.5⁰

Physics
F(fr) +mg= F(y) F(y) = Fsinα F(fr) =Fsinα-mg

Physics
W=PE+KE+W(fr) =mgh+mv²/2 +W(fr) = =m(gh+ v²/2)+W(fr) =1260(0.6•9.8 +3²/2)+2870 = =13078.8+2870 =15948.8 J

Physics
mv²/2 =W(fr) = μNs= μmgs μ=v²/2gs =5.8²/2•9.8•20 =0.086

Electricity and Electronics
15. A 19. D

physics
d(x)=dcos46⁰=110•cos46⁰=76.4 m. d(y) =- dsin46⁰=- 110•sin46⁰= - 79.1 m. v(x) = vcos28⁰=350•cos28⁰= 309 m/s v(y) = vsin28⁰=350•sin28⁰=164.3 m/s a(x) = 0 a(y) = - 9 m/s²

Physics
Magnetic ﬁeld at the center of a circular current-carrying loop of N turns and radius r is B=Nμ₀I/2r….. (1) N=L/2πr ….(2) I=U/R=U/R₀L ….(3) Substitution (2) and (3) in (1) gives B=Nμ₀I/2r = (L/2πr) •(μ&#...

Physics
ma=F mv²/R =qvBsinα. v⊥B => sinα = 1. mv/R =qB, R = mv/ qB, T=2πR/v=2π m /qB= = 2π/B(q/m) =2π/0.69•5.7•10⁸0.69= =1.6•10⁻⁸ s

Physics
http://einstein.drexel.edu/~wking/courses/phys101_w07/hwk/hwk4.pdf

physics
(a) the work done by the applied force W=F(x) •s=F•cos α•s= 18.6•cos23.7•2.09 = …. (b) the magnitude of the normal force exerted by the table N =mg+F(y) =mg+Fsin α = 2.4•9.8 +18.6•sin23.7 = … (c) the magnitude of the force...

physics
d=17.7 m vₒ =15.4 m/s α =38.7⁰ =>2 α =77.4⁰ L=vₒ²•sin2α/g=15.4²•sin77.4/9.8 =23.6 m t= 2vₒ•sinα/g=2•15.4•sin38.7/9.8 = 1.97 s. s=(L-d)/t =(23.6-17.7)/1.97 =3 m/s

Physicis
Make the route plan s₁= 300 =x₁+x₂ s₂ =395, α =26.5⁰ s₃ = 150 x₃ connects the point of s₂ and s₃ intersection and the point on s₁ which divides s₁ by x₁ and x₂ (x₃ ⊥ s₁) s&#...

Physics
(A) L=18.3 m, h=0.809 m h=gt²/2 t=sqrt(2h/g) = .... L=vt => v=L/t=.... (B) h=gt²/2 t=sqrt(2h/g) = … L₁=v₁t =... L₂=v₂t =....

physics
d(x)=dcos46⁰=110•cos46⁰=76.4 m. d(y) =- dsin46⁰=- 110•sin46⁰= - 79.1 m. v(x) = vcos28⁰=350•cos28⁰= 309 m/s v(y) = vsin28⁰=350•sin28⁰=164.3 m/s a(x) = 0 a(y) = - 9 m/s²

Physics
(A) v=gt t=v/g h=gt²/2 =gv²/2g²=v²/2g (B) mv²/2 = mgh h= v²/2g

physics
g=1.6 m/s² Upward motion v=v₀-gt v=0 t= v₀/g=5/1.6 =3.125 s Downward motion t₁=15-3.125 =11.875 m/s v=gt₁=1.6•11.875=19 m/s

Physics
F₁ =qvBsinα₁ F₂ =qvBsinα₂ F₂=2.4F₁ F₁/F₂=1/2.4 =qvBsinα₁/qvBsinα₂ sin α₂=2.4•sin α₁ =2.4•sin19⁰=0.78 α₂=51.4⁰

physics urgent please help!
v=81.7 km/h =81700/3600=22.7 m/s d= v²/2a=22.7²/300=1.72 m

PHYSICS HELP PLEASE!!
v=81.7 km/h =81700/3600=22.7 m/s d= v²/2a=22.7²/300=1.72 m

Physics
6.7 lb = 3.04 kg mg₁=3.04•9.8 =29.8 N mg₂=mg₁/6 =3.04•9.8/6=4.97 N

phusics
a=v²/2s F=ma=m v²/2s =2.1•10⁵•30²/2•120 = 787500 N

phys223
http://answers.yahoo.com/question/index?qid=20130422100626AAOAlzD

physics
v =at => a=v/t P=W/t = Fs/t=Fv = ma•v= mv²/t

physics
KE=PE mv₀²/2=mgh=mgxsinα x= v₀²/2gsinα=3²/2•9.8•sin22=1.23 m. a₁=v₀²/2x =9/2•1.23=3.66 m/s² Upward v= v₀-a₁t₁ v=0 t₁=v₀/a₁=3/3.66=0.82 s. Downward PE=KE mgxsinα= ...

physics
http://answers.yahoo.com/question/index?qid=20110214141546AAp0rSP

Physics
An initial velocity of the projectile v₀ = the velocity of the plane. v₀ (x) = v₀cosα, v₀ (y) = v₀sinα, h= v₀ (y) •t+ gt²/2= =v₀sinα•t + gt²/2. v₀={h- gt²/2}/ sinα•t= ={790 –...

science
p=mg/A = 50•9.8/2(0.15•0.005)= =326666 Pa

Physics
x: Fcosα-μN =0, y: mg-N-Fsinα=0 =>N= mg-Fsinα, μ= Fcosα/N = Fcosα/(mg-Fsinα)= =77•cos30/(24.5•9.8-77•sin30)= =0.33

physics
h=gt²/2 = 10•2²/2=20 m v=gt =10•2 =20 m/s v=v₀-gt₁ v=0 t₁= v₀/g=15/10=1.5 s h₁=v₀t₁-gt₁²/2 = =15•1.5 -10•1.5²/2=11.25 m a=Δv/Δt= (-15-20)/0.02= - 1750 m/s

physics
1 amu = 1.6605•10⁻²⁷ kg 19.992439 amu = 3.3197•10⁻²⁶ kg m=10 m(p) +10 m(n) = =10• (1.6726+1.6749) •10⁻²⁷ = =3.3475•10⁻²⁶ kg Δm=(3.3475-3.3197) •10⁻²⁶= =0....

Physics
s₁=45 m α=26⁰ s₂=? ΔPE +W(fr)₁ =KE =W(fr)₂, ΔPE +W(fr)₁ =W(fr)₂, mgh+ F(fr)₁•s₁ = F(fr)₂•s₂. h=s₁•sinα, F(fr)₁ =μ•N₁=μ•mgcosα, F(fr...

AP Physics
mg=mv²/r v=sqrt(rg)

Physics
a=ω²R =(2πn)²R= (2•3.14•60)²•0.15 = …

Physics
a. sandpaper

physics
L=vₒ²•sin2α/g= vₒ²•2sinα•cosα/g h= vₒ²•sin²α/2g, L/h= 2•vₒ²•2sinα•cosα•g/ vₒ²•sin²α• g= =4/tanα tanα = 4h/L = 4•...

physics
v₁=v₀-gt₁ v₀=v₁+ gt₁=18+9.8•5.4= 40.54 m/s At the top point v=0 0 =v₀-gt t = v₀/g=40.54/9.8 =4.14 s. t₃=t₂- t=5.4 – 4.14 = 1.26 s v₂=gt₃ = 9.8•1.26 = 12.38 m/s (directed dowmward)

Physics
A(x) =45.6•cos51.2 = 28.57 A(y) = 45.6•sin51.2 =35.74 B(x)= -23.6•cos32.8 = -19.84 B(y) = 23.6•sin32.8=12.78 C(x) = 0 C(y) = -34 (A-B+C)(x)= 28.57-(-19.84) +0 =47.84 (A-B+C)(y) = 35.74-12.78 +(-34)=-11.04 (A-B+C) =sqrt[47.84²+(-11.04)²] = 49.1 tan...

college physics
Example 2.2: Electric Field on the Axis of a Rod (page 2-17) http://web.mit.edu/viz/EM/visualizations/coursenotes/modules/guide02.pdf

college physics
F=k•q₁•q₂/r² k =9•10⁹ N•m²/C² e =1.6•10⁻¹⁹ C. F=k•e²/r²= =9•10⁹•(1.6•10⁻¹⁹)²/(0.542•10⁻¹⁰)² = =7.84•10⁻&#...

physics
N= 0.1 rev n= 4.31•10² rev/s t=N/n = 0.1/4.31•10² = 2.32 •10⁻⁴ s v=s/t =60000/2.32•10⁻⁴=2.59•10⁸ m/s Ans. d

physics
h =s/2 = vt/2= 1530•8/2 =6120 m

Pysics
t₁=s₁/v₁ =185/6=30.83 s t₂=s₂/v₂= 310/2=155 s v(ave) =(s₁+s₂)/(t₁+t₂)= =(185+310)/(30.83+155)=2.66 m/s

physics
s=at²/2 a=2s/t² F=ma eU =Fs =mas =m2s²/t² U= 2ms²/et² = =2•9.1•10⁻³¹•(0.15)²/1.6•10⁻¹⁹•(19•10⁻⁹)²= =709 V

physics
http://www.physicsforums.com/showthread.php?t=200266

PHYSICS!!!
a=ω²R =(2π/T)²R =4g T= πsqrt(R/g)= 3.7 s

college physics
http://www.physics.drexel.edu/~wking/courses/phys102_s08/notes/rec1_sols.pdf

physics
v= v₀ + at v₀=0 a=v/t=21500/3600•6.9 =0.87 m/s² s= at²/2 = 0.87•6.9²/2=20.6 m

physics
mgh₁ = mv₁²/2 v₁=sqrt(2gh₁) = sqrt(2•9.8•4.31)=9.2 m/s mv₂²/2= mgh₂ v₂ =sqrt(2gh₂) = sqrt(2•9.8•2.51)=7 m/s a=[v(fin) – v(in)]/t v(fin) =v₂ (directed upward ) v(in)] = v₁ (directed ...

Physics
v₀=7m/s; d=4 m; L 45 m; a= 0.5 m/s². (v₀t + at²/2) - (v₀t) = d t =sqrt (2d/a) = sqrt(2•4/0.5) = 2.83 s (a) t=2.83 s v₁=v₀+at = 7 + 0.5•2.83 = 8.42 m/s x = v₀t+ at²/2 = 7•2.83 + 0.5•2.83²= 21.8 m (b) s...

physics
(a) Upward motion v=v₀ -gt v=0 v₀ =gt =9.8•1.9 =18.62 m/s (b) h=v₀t -gt²/2 = 18.62•1.9 - 9.8•1.9²/2= =35.38 – 17.69 = 17.69 m (c) If H is the height of the building t₀= 9 – 1.9 = 7.1 s H+h = gt₀²/2 = 9.8&#...

physics
h= gt²/2 t=sqrt(2h/g) = sqrt(2•196/9.8)=6.32 s. The first 96 m h/2=gt₁²/2 t₁=sqrt(h/g)=sqrt(196/9.8)=4.47 s. The 2nd 96 m t₂=t-t₁=6.32-4.47 =1.85 s

Physics
h=v₀t +gt²/2 v= v₀+gt v₀ =v-gt h=( v-gt)t + gt²/2 = =vt - gt² + gt²/2= = vt - gt²/2. gt² -2vt +2h = 0 t = (2•34.9±sqrt{(2•34.9)²-4•9.8•2•34.9}/2•9.8 = 0.7 s v₀ =v-gt =34.9 – 9....

physics
n=30 rpm = 30/60 =0.5 rev/s ω=2πn =2π•0.5 = π =3.14 rad/s (along the axis of rotation)

physics
See the answer in Related Questions

phyiscs
H=gt²/2 t =sqrt(2H/g) = sqrt(2•81/9.8)=4.07 s h=(1-0.28)H =58.32 s t₁ =sqrt(2h/g) =3.45 s. t₂=4.07 – 3.45 = 0.62 s. v₁=gt₁ =9.8•3.45 =33.81 m/s v₂ = gt₂ =9.8•4.07 = 39.89 m/s

Physics
F =G•m₁•m₂/R² the gravitational constant G =6.67•10⁻¹¹ N•m²/kg², F₁=F₂ = G•m₁•m₂/R²= =6.67•10⁻¹¹•1•100/1²=6.67•10⁻ ⁹ N.

physics
T₁=2πsqrt(m₁/k) T₂ =2πsqrt(m₂/k) T₂ /T₁ =sqrt{ m₂/m₁} T₂ = T₁sqrt{ m₂/m₁}= =3.5•sqrt(2/1) =4.95 s.

Phyics
v₂t +at²/2 -v₁t =10.7 0.6t²-2.6t -10.7 =0 t=6.92 s

physics
1. F(el) =F(magn) qE=qvB v=E/B=1.08•10⁴/2•10⁻³ =5.4•10⁶ m/s ma=mv²/R= qvB q/m=v/RB =5.4•10⁶/1.53•10⁻²•2•10⁻³ = =1.76•10¹¹ C/kg +> This is electron (e/m= 1.6•10&#...

physics
Centripetal acceleration a=ω²•R =(2πn)²•R =4π²n²•R => n=sqrt{aR/4π²} =sqrt{1090•9.8•0.123/4•π²}=5.77 rev/s

physics
v=v₀+at a= (v-v₀)/t

physics
(a) E=0 (b) E=k•2λ/r =9•10⁹•2•36•10⁻⁹/0.135=4800 N/C (c) E=k•2λ/r =9•10⁹•2•36•10⁻⁹/1.25=518.4 N/C

Physical Science
Two magnets will be attacted by their opposite poles, and each will repel the like pole of the other magnet. A. attract each other.

science
Osmosis http://en.wikipedia.org/wiki/Osmosis http://www.beaconlearningcenter.com/documents/1965_3263.pdf

physics
pressure = Weight/area = mg/A = = 50000 x 9.8/5 = 98000 Pa

physics
ma=-mg +F a= F/m- g = 1005/92.3 - 9.8 = =10.9 -9.8 = 1.1 m/s²

Physic,
From http://teacher.nsrl.rochester.edu/phy_labs/appendixe/appendixe.html Error in experiments have several sources. First, there is error intrinsic to instruments of measurement. Because this type of error has equal probability of producing a measurement higher or lower ...

physics
P=Fv v=P/F

Physics
mv=(m+M)u u=mv/(m+M)

Physics (Kinematics)
s= at²/2

Physics (Kinematics)
s=at²/2 a=2s/t² = …

Physics (Kinematics)
v=v₀+at a=(v-v₀)/t = … s= v₀t + at²/2=...

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