Unit 4: Oscillatory Motion and Mechanical Waves
Terms: Oscillation: a repetitive back and forth motion Cycle: one complete oscillation Period (T): time for one complete oscillation Frequency ( f ): number of oscillations per second.
Simple Harmonic Motion Repetitive back and forth motion Hooke’s Law Force varies directly with displacement Equilibrium position: spring is neither compressed or expanded. Spring Constant (k): spring stiffness (N/m) Slope of a F vs. x graph is the spring constant
Restoring Force: Force that moves the object back to its equilibrium position. Always acts in a direction opposite to the displacement When representing the restoring force:
Horizontal SHM Amplitude: maximum displacement. At max displacement, the restoring force is at maximum When the mass is let go, the mass will accelerate towards the equilibrium position. ( F = ma) As the mass moves through the equilibrium position, it will slow down.
Vertical SHM Mass will come to rest when Fg is equal to the upward pull of the spring (at equilibrium)
Example: An spring has a spring constant of 40.0 N/m. This spring is pulled with a force of 85.0 N to the left. What is the extension?
Example: A 675 g mass is hung vertically from a spring. If the spring has a constant of 15.0 N/m, how far was the spring stretched?
Homework: Page 347 #7, 9-12 Page 352 #1-2 Page 354 #1-2 Page 357 #1-2