The Center of Mass of Water Find the center of mass of a water molecule, referring to Figu...

The Center of Mass of Water Find the center of mass of a water molecule, referring to Figure9-26. for the relevant angles and distances. The mass of a hydrogen atom is 1.0 u, and the mass of an oxygen atom is 16 u, where u is the atomic mass unit (see Problem). Use the center of the oxygen atom as the origin of your coordinate system.

△Figure 9-26 Problem

Problem

Moderating a Neutron In a nuclear reactor, neutrons released by nuclear fission must be slowed down before they can trigger additional reactions in other nuclei. To see what sort of material is most effective in slowing (or moderating) a neutron, calculate the ratio of a neutron’s final kinetic energy to its initial kinetic energy, Kf/Ki, for a head-on elastic collision with each of the following stationary target particles. (Note: The mass of a neutron is m = 1.009 u, where the atomic mass unit, u, is defined as follows: 1 u = 1.66 × 10−27 kg.) (a) An electron (M = 5.49 × 10−4 u). (b) A proton (M = 1.007 u). (c) The nucleus of a lead atom (M = 207.2 u).