Harmonic Motion Chapter 11 Mr. Rassi

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

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

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

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)

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

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

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