Periodic Motion2 PHYS116 A01 32910 Lecture 30 Momchil

Periodic Motion-2 PHYS-116 A-01, 3/29/10, Lecture 30 Momchil Velkovsky

Energy in SHM • Energy is conserved during SHM and the forms (potential and kinetic) interconvert as the position of the object in motion changes.

Energy in SHM II • The figure shows the inter-conversion of kinetic and potential energy with an energy versus position graphic.

Energy and momentum are related in SHM

To double the total energy of a mass-spring system oscillating in simple harmonic motion, the amplitude must increase by a factor of 1. 4. 2. 3. 2. 4. 5.

Angular SHM • Watches keep time based on regular oscillations of a balance wheel initially set in motion by a spring.

Vibrations of molecules • Two atoms separated by their inter-atomic distance r can be pondered as two balls on a spring. The potential energy of such a model is constructed many different ways. The Lennard–Jones potential is shown.

The physical pendulum • A physical pendulum is any real pendulum that uses an extended body in motion.

Dinosaurs, long tails, and the physical pendulum • The stride of Tyrannosaurus rex can be treated as a physical pendulum.

A simple pendulum consists of a point mass suspended by a massless, unstretchable string. If the mass is doubled while the length of the string remains the same, the period of the pendulum • • • A. becomes 4 times greater. B. becomes twice as great. C. becomes greater by a factor of. D. remains unchanged. E. decreases.

Reading for next time • Chapter 13. 4 -13. 8 • Try problems 13. 17, 13. 31, 13. 35, 13. 49, 13. 55