1. Harmonic Motion
Chapter 11
Mr. Rassi

2. Simple Harmonic Motion
restoring force is proportional to distance from equilibrium
- example - mass on a spring
Hooke’s Law: Felastic = -kx
Equilibrium & extremes

3. Springs
F = -kx
k is spring constant – depends on material & tightness of coil
Energy in stretched or compressed spring (½kx2)
Examples – Cars, bowstrings

4. Pendulums Simple pendulum example of harmonic motion
Restoring force gravity – chart page 375

5. Pendulums Measures of simple harmonic motion
Amplitude (A)– maximum displacement from equilibrium
Period (T)– time for one cycle
Frequency (f)– number of cycles per unit time (Hertz s-1)

6. Pendulums
Period of Pendulum depends on its length & gravity acceleration
T = 2π√(L/g)
Mini-Lab – find period & frequency & amplitude of Pendulum

7. Pendulums Grandfather clocks – why so tall?
Want exactly 1 second every time the pendulum passes equilibrium
Chronometer challenge – need a good clock for sailing ships
John Harrison solved it - springs

8. Springs Spring clocks T = 2Π√(m/k)
Mini Spring Lab – finding the spring constant