The subject of moving reference frames is of importance in the study of forces, energy and momentum (Chapters 4-8). Since both kinetic energy and momentum depend on the velocity, observers who disagre...The subject of moving reference frames is of importance in the study of forces, energy and momentum (Chapters 4-8). Since both kinetic energy and momentum depend on the velocity, observers who disagree on the value of an object's velocity also will not agree on the value of the momentum or the kinetic energy. They are said to be viewing the motion from two different frames of reference. So who is measuring the correct value for the momentum and energy?