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1. ### Neutron energy needed to produce fission of 208Pb

Homework Statement Estimate the neutron energy needed to produce fission of 208Pb. Is it likely that such neutrons woould be released in the resulting fission? Homework Equations Eexcitation=Qexcitation+Tn Qexcitation=[m(208Pb)+mn-m(209Pb)]c2 V=(e2/4πεo)(Z1Z2/r)...
2. ### Polarization by reflection and Brewsters Angle

Homework Statement A beam of light is reflected off the surface of some unknown liquid, and the light is examined with a linear sheet polarizer. It is found that when the central axis of the polarizer (that is, perpendicular to the plane of the sheet) is tilted down from the vertical at an...
3. ### Group Velocity in terms of Wavlength and velocity

Got it, thanks that was way easier than I was making it
4. ### Group Velocity in terms of Wavlength and velocity

Homework Statement Show that the group velocity vg=dω/dk can be written as vg=v-λ*dv/dλ where v = phase velocity Homework Equations n=n(k)=c/v k=2∏/λ ω=2∏f=kv fλ=c The Attempt at a Solution dω/dk = d(kv)/dk= v+k(dv/dk)= v+ck(d(n^-1)/dk) =v-(ck/n^2)(dn/dk)...
5. ### Pendulum suspended from Horizontal rotating hoop

Homework Statement A massless hoop is suspended horizontally and is free to rotate about a vertical axis through its center with a constant angular velocity (omega). Attached to the edge of the hoop is a simple pendulum that is restricted to oscillate in only the radial direction. find the...
6. ### Lagrangian of suspended rod

Homework Statement A thin rod of length 2b is suspended by 2 light strings both attached to the ceiling. Using x, y1, y2 as your generalized coordinates right down the lagrangian of the system. Where x is the longitudinal displacement of the rod and y1 and y2 are the horizontal displacements...