Rolling motion, energy

The over-all length of the chute, 58 inches, forces each fruit to rotate completely five to six times during its passage. Since the fruits are injected by a gating system normal to the irradiation chute, they already have some rotational energy in this direction. The effect is to add some gyrating motion to the fruits as they roll through the chute. Each element of the surface is then exposed to the variety of flux patterns as it rotates the five to six complete turns to the exit. 

We will not discuss the actual construction of potential energy surfaces. This monograph deals exclusively with the nuclear motion taking place on a PES and the relation of the various types of cross sections to particular features of the PES. The investigation of molecular dynamics is — in the context of classical mechanics — equivalent to rolling a billiard ball on a multi-dimensional surface. The way in which the forces i fc(Q) determine the route of the billiard ball is the central topic of this monograph. In the following we discuss briefly two illustrative examples which play key roles in the subsequent chapters. 

Friction is defined as the resistance encountered when one body moves tangentially over another and they are in contact. Friction often embraces two classes of relative motion sliding and rolling. In industrial processes, frictional energy is usually dissipated as waste heat. The friction force is represented by F and the friction coefficient by p. Under many sliding conditions, the p for a given pair of materials and fixed conditions of lubrication is mostly constant. The three laws of friction are ... 

If, however, the same amount of energy is present solely as translational kinetic energy, then the system moves along a successful encounter trajectory C and travels smoothly over the saddle point into products. We can therefore conclude that reactions with attractive potential energy surfaces proceed more efficiently if the energy is in relative translational motion. Moreover, the potential surface shows that once past the saddle point the trajectory runs up the steep wall of the product valley, and then rolls from side to side as it falls to the foot of the valley as the products separate. In other words, the products emerge in a vibrationally excited state. 

If a dwell time is required or desired in punch-and-die presses (Fig. 5.11, upper right), special drive systems must be used [B.48, B.97]. It is obvious from Fig. 5.11, lower left and right, that no such possibility exists in roller presses where a continuous rolling action densifies the material between approaching surfaces until, immediately after passing the point of closest approximation, the relative motion is reversed, the surfaces retract, and the pressing force drops, ideally to zero if no expansion due to compressed gas and/or stored elastic energy takes place. 

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