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    Kirchoff rule

    Homework Statement write two independent equations using kirchoff rule to describe the circuit. Homework Equations V=IR Emf = IR The Attempt at a Solution The answer is emf2 -I1R3-I2R2-I1R1 = 0 (ok i have questions here: why is it I1R1? shouldnt it be I4R1?) and...
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    One voltage, 3 resistors

    Homework Statement A circuit with one 5V and 3 resistors in parallel. What is the voltage across one of the resistors? Homework Equations V=IR The Attempt at a Solution 5/3 V?? or should i put R1 = 5V/I -R2-R3 V how do we get voltage across one of the resistors without...
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    Intergration Dipole

    wats the R for V_a? wats the R for V_p? are they different? i think the R for V_a is ((s/2)^2 + d^2 ) )^ (1/2) but for V_p.... is it just s/2? if thats true i dont think i will get 0 for \DeltaV = V_p - V_A
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    Intergration Dipole

    Homework Statement We know the magnitude of the electric field at a location on the x axis and at a location on the y axis, if we are far from the dipole. (a) Find \DeltaV= V_p - V_a along a line perpendicular to the axis of a dipole. Do it two ways: from superposition of V due to the two...
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    2 Protons

    Homework Statement He2+ 2 protons and 2 neutrons Homework Equations E = Kq/r^2 The Attempt at a Solution to get q do square the charges of the proton? or do I multipy it by 2
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    Unwinding Cylinder-Dynamics

    im having trouble with part c it says its a yoyo and the string is wrapped around the axis and the radius casing >>>> radius of axis but i didnt that would matter because the string is wrapped around the axis but then the problem says I >>>> m(r_axis)^2 and then i go ...
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    Unwinding Cylinder-Dynamics

    is that right? now that im looking at the problem more if T = mg shouldnt a_y equal to 0?
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    Unwinding Cylinder-Dynamics

    ok for vertical a in the -y direction a_y = ( -gmr^2 ) / (I + mr^2) i dont see T in the equation so but it has to affect a_y but i do see I and if i make that equal to 0 i get a_y = -g WOWOW thats amazing thanks!
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    Unwinding Cylinder-Dynamics

    ur right i contradicted myself anyway my logic tells me if t = 0, there is no tension and the object should just fall and so -y direction its a=g (linear) but the equations tells me otherwise that when t = 0 a = 0 (as seen in picture) that does not make sense to me...
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    Unwinding Cylinder-Dynamics

    im having trouble with part B i think when t=0, a = 0 because if I goes to zero, t no longer does work on rotation but does work on linear acceleration but if the tension goes to 0 then the object will continue to spin but simply fall in the -y direction due to gravity right?
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    Unwinding Cylinder-Dynamics

    Unwinding Cylinder--Dynamics Homework Statement A cylinder with a moment of inertia I (about its axis of symmetry), mass m, and radius r has a massless string wrapped around it which is tied to the ceiling (Intro 1 figure) . At time t=0 the cylinder is released from rest at height h...
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    Moving two blocks connected by a spring

    what are you trying to say? the initial energy = 0 becuz the objects are at rest and spring is at its natural lenght so therefore the final energy is K + U which is equal to Wd that? and so .5m(v_1f)^2+.5m(v_2f)^2-.5kx^2 = (100N/m)(.08m) KE m1 KE m2...
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    Moving two blocks connected by a spring

    Homework Statement m_1, v_1f m_2, v_2f m_2 = m_1 = m Homework Equations KE = .5mv^2 W = F*d spring: F= -kx pot energy = PE = -.5kx^2 The Attempt at a Solution A) K + U = .5m(v_1f)^2 + .5m(v_2f)^2 - .5kx^2 .5(.1kg)(v_1f)^2 + .5(.1kg)(v_2f)^2 -.5(100N/m)(.02m)^2 B) ...
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    The Rotational Kinetic Energy of the Earth

    Homework Statement The Earth can be approximated as a sphere of uniform density, rotating on its axis once a day. The mass of the Earth is 5.97×10^24 kg, the radius of the Earth is 6.38×10^6 m, and the period of rotation for the Earth is 24.0 hrs. What is the moment of inertia of the...
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    Spinning situation

    Homework Statement Suppose you are standing on the center of a merry-go-round that is at rest. You are holding a spinning bicycle wheel over your head so that its rotation axis is pointing upward. The wheel is rotating counterclockwise when observed from above. For this problem, neglect...
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    Colliding Balls

    Homework Statement There are two balls travelling and they collide. How do there momentum change. What is the impulse done to ball B by ball A. Homework Equations delta momentum = 0 impulse = ? The Attempt at a Solution the first part i think its C becuz A is moving up...
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    An Exciting Encounter

    Homework Statement its asking me if if it is easier to use the mass units Homework Equations PART A The Attempt at a Solution its it easier to to use numbers given becuz when add the numbers (3.9) / ( 1 - 16 / (16+133) ) = 4.3 = kinetic energy needed for O ionize C 4.3 > 4...
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    Weird globe

    ok the next questions asks about about momentum im thinking centripital acceleration cannot be zero becuz is it zero? i dont think so becuz its traveling on a circular path prior to leaving the globe normal force must be zero becuz nothing is pushing up the net acceleration is...
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    Two worlds spinning

    Homework Statement There are two balls with masses m_a and m_b connected by a string. m_b is moving at a velocity v upwards (perpendicular to the string) and it asks for the Tension (T) in the string. Homework Equations a=(v^2)/R delta Energy of system = 0 T = m((u^2)/r) u is...
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    Weird globe

    and so it is a and c becuz once the block leaves the globe nothing is pushing the box up (but friction) and nothing is slowing the box down in the horizontal direction (but friction) and so the only force is the earth? right?
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    Weird globe

    Homework Statement there is a block sliding down a big globe in Italy. Homework Equations uhh The Attempt at a Solution does the globe have its own gravity? i'm thinking its A and C.
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    Launching from Mars

    im solving for Vo the object is launched from above the atmosphere im given the distance between object and mars (R_m) and I'm given the weight of mars (m) and I'm given Vf of the object so what I did (but I did not get a good answer) was use F=Gm1m2/r^2 m1 = object m2 =...
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    Launching from Mars

    Homework Statement The Radius of Mars is R_m its mass is m The radius of Mars (from the center to just above the atmosphere) is R_m and its mass is m. An object is launched from just above the atmosphere of mars. A) what is the object's initial velocity if its final velocity is V_f Homework...
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    Two blocks of power (2)

    ok now both the blocks have the same speed and now have the same V ok... and its asking for distance so i have to find out how far each box is pushed and work of larger box = W_L= F*D_L W_S=F*D_S KE_L = .5(4M)(v)^2 KE_S = .5(M)(v)^2 and since W=chainge in KE (KE_initial...
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    Two blocks of power (2)

    ok for part b it is asking how fast the lighter block is moving when compared to the big block. im thinking the F*D is the same and KE is .5mv^2 and so .5(4m)(v_L)^2 = .5m(v_S)^2 the m and .5 cancel out so i have 4(V_L)^2=(V_S)^2 SQRT BOTH SIDE and then V_S = 2V_L so therefore the...
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    Power dissipation

    ok i figured out the first part how do i figure out part B? I kno the power is proportional to v^3 and so if i increase the power by 10% i should get ?? if Pi = -(vi^3)AC_d then 1.1Pi=-(vf^3)AC_d Pi = (-(vf^3)AC_d ) / 1.1 (vf^3) = 1.1(vi^3) then what?
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    Power dissipation

    Homework Statement Homework Equations P=F*V The Attempt at a Solution why isn't it P = Cd(A^2)(v^2) * (v) i dont see what i could do
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    Two blocks of power

    how do i delete this?
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    Two blocks of power (2)

    Homework Statement the force is given as F the distance pushed is given as D Homework Equations W= F*d F=ma KE = 1/2 mv^2 The Attempt at a Solution the blocks have the same kinetic energy
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