Two life preservers have identical volumes, but one is filled with Styrofoam while the other is filled with sand. When the two life preservers are worn by swimmers, one swimmer floats with part of the preserver above water, and the other swimmer sinks. In this case the buoyant force is greater on the life preserver filled with:.
A) Styrofoam.
B) Sand.
C) Same on each as long as their volumes are the same.

How does the amount of energy required to hold each proton and neutron in the nucleus compare to the energy released when they are removed?

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.

The heliocentric and the geocentric models of the solar system included these central principles