1. Welcome to Physics 7C Emily Ashbaugh eashbaugh@physics.ucdavis.edu

2. Some Logistics Course Webpage: http://physics.ucdavis.edu/physics7 http://physics.ucdavis.edu/physics7

3. Simple Harmonic Oscillation Review How can we describe the motion of oscillating objects?

4. Simple Harmonic Motion (SHM) Constructs Amplitude: maximum distance from equilibrium Period (or frequency): amount of time required to complete a cycle (or number of cycles per unit time) Equilibrium: position at which all forces acting on the object sum to zero. Displacement: position of the object relative to equilibrium Restoring Force: a force that acts on an object that tends move it toward equilibrium Defining SHM: The restoring force is proportional to the displacement. Anything missing?

5. Mathematics of SHM y=Displacement A=Amplitude T=Period t y In this image, which numbers, if any, show… Displacement? 1 4 3 5 2 6 Amplitude? Period?

6. Mathematics of SHM y=Displacement A=Amplitude T=Period t y y(t) = A sin (2 t/T)??? In this image, what is the mass doing at t=0 seconds? A T T A Is the equation correct as is?

7. Mathematics of SHM y=Displacement A=Amplitude T=Period t y y(t) = A sin (2 t/T + ) In this image, what is the mass doing at t=0 seconds? In this image, what value does  have? T  =phase y(t) = A sin (2 t/T)? A

8. Making Waves Watch waves How does the motion you are watching differ from the motion of the mass-spring? How is it the same? What new constructs are needed to describe waves? What constructs can I control when I start the wave? What moves from one end of the machine to the other?

9. Wave Constructs Waves: A transfer of energy without bringing along the mass. Particles in the medium get disturbed and collide, but they stay oscillating about one position; they don’t travel with the wave. The medium does not effectively move. The disturbance advances, that’s the wave.

10. Graphing Waves a) At a particular time (holding position constant) b) At a particular position (holding time constant)

11. Mathematics of Harmonic Waves Displacement (y) is a function of both position along the medium and time. y(x,t) In space, function repeats every wavelength In time, function repeats every period

12. Longitudinal vs. Transverse Wave Polarization Longitudinal WaveTransverse Wave `