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12.1 Simple Harmonic Motion. Date, Section, Pages, etc. Mr. Richter. Agenda. Warm Up Any paper stragglers? Intro to Simple Harmonic Motion Notes: Simple Harmonic Motion Springs and Hooke’s Law Simple Pendulums Motion and Energy in SHM. Objectives: We Will Be Able To….
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12.1 Simple Harmonic Motion Date, Section, Pages, etc. Mr. Richter
Agenda • Warm Up • Any paper stragglers? • Intro to Simple Harmonic Motion • Notes: • Simple Harmonic Motion • Springs and Hooke’s Law • Simple Pendulums • Motion and Energy in SHM
Objectives: We Will Be Able To… • Identify the conditions of simple harmonic motion (SHM) • Explain how force, velocity, and acceleration change as an object vibrates with simple harmonic motion. • Calculate the spring force using Hooke’s Law.
Warm Up • A metronome keeps a ticking count of 90 beats per minute. • What is its period of oscillation? • What is its frequency of oscillation?
Introduction to Simple Harmonic Motion • What keeps an object bouncing up and down on a spring? • What would cause this to stop?
Vibrations and Waves • Vibration: any repeated motion of an object moving back and forth, or oscillating • Fans • Mass at the end of a spring. • Pendulums. • Waves are formed when a stationary substance vibrates. • Ripples in water. • Vibrating air with sound waves. • Whipping a rope.
Simple Harmonic Motion (SHM) • “any periodic motion that is the result of a restoring force that is proportional to displacement” • Basically: back-and-forth motion over the same path. • Restoring Force: Object tends to want to return to original position. (Location is “restored”).
Hooke’s Law (Springs!) • Most mass-spring systems obey a simple (proportional) relationship between force and displacement. • This is also true of systems that can be modeled by a mass and spring. • This relationship is called Hooke’s Law • k = spring constant [N/m] • Force (F) always in opposite direction of displacement (restoring!)
The Simple Pendulum • Mass is called “bob”. Assume string is weightless. • Restoring force is a component of the weight of the bob. • Fg = mgsinθ • For small angles, the pendulum’s motion is simple harmonic.
Energy During SHM • Total mechanical energy stays the same. • Trade off between potential and kinetic energy.
Wrap-Up: Did we meet our objectives? • Identify the conditions of simple harmonic motion (SHM) • Explain how force, velocity, and acceleration change as an object vibrates with simple harmonic motion. • Calculate the spring force using Hooke’s Law.
Homework • p. 441 #e,4 • p. 445 #1, 2, 4