We can understand why 235u is readily fissionable, and 238u is not, by usingthe following calculation.
(a) find the energy difference between 235u + nand 236u. we can regard this as the "excitation energy" of 236u.
(b) repeat (a) for 238u + nand 239u.(c) (2 pts) comparing your results for (a) and (b), explain why 235u will fission with very low energy neutrons, while 238u requires fast neutrons of 1 to 2mev of energy to fission.

Look at the spectrums of a star moving towards earth and a motionless star. which of these is a correct inference that can be draw from the observation of the two spectrums? (2 points) the spectrum of a motionless star is difficult to be viewed separately using oridinary telescopes. the spectrum of a motionless star is identical to the spectrum of a star which moves towards earth. the spectrum of a star shifts towards the red region when the star moves towards earth. the spectrum of a star shifts towards the blue region when the star moves towards earth.