Afisherman of mass m = 90.8~\mathrm{kg}m=90.8 kg is sitting in a canoe with mass m = 176~\mathrm{kg}m=176 kg on a warm summer day. the canoe has length l=7.32~\mathrm{m}l=7.32 m and he is sitting at the very end of the canoe. after several hours of not catching anything, he decides to try his luck from the other end of the boat, so he gets up and walks over to the other end of the canoe, then sits down again. assuming that the water applies no frictional force on the canoe, what is the (magnitude of the) distance the canoe itself has traveled in this process?

The particle in a two-dimensional well is a useful model for the motion of electrons around the indole ring (3), the conjugated cycle found in the side chain of tryptophan. we may regard indole as a rectangle with sides of length 280 pm and 450 pm, with 10 electrons in the conjugated p system. as in case study 9.1, we assume that in the ground state of the molecule each quantized level is occupied by two electrons. (a) calculate the energy of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels. 9.27 electrons around the porphine ring (4), the conjugated macrocycle that forms the structural basis of the heme group and the chlorophylls. we may treat the group as a circular ring of radius 440 pm, with 20 electrons in the conjugated system moving along the perimeter of the ring. as in exercise 9.26, assume that in the ground state of the molecule quantized each level is occupied by two electrons. (a) calculate the energy and angular momentum of an electron in the highest occupied level. (b) calculate the frequency of radiation that can induce a transition between the highest occupied and lowest unoccupied levels.