Vocabulary (Due Tue 3/20): Today’s HW & Agenda Vocabulary (Due Tue 3/20): Ch. 12 Vocabulary part 1 Wavelength Amplitude Period Frequency Transverse Longitudinal Medium Crest Trough Node antinode Review Ch. 8 & 9 Exam Review Ch. 12 Reading HW8 Simple Harmonic Motion Activity Lecture Hooke’s Law, Mass-Spring Systems, & Pendulums HW9: 12A p.441 # 1, 2, 3 Sect Rev p.445 #1, 2, 3 12B p. 449 #1, 2, 3, First 5 vocabulary Terms Textbook Chapter 12

periodic motion & Waves video https://www.youtube.com/watch?v=j6KhwOQlIh8&feature=iv&src_vid=jAXx0018QCc&annotation_id=annotation_829607

Simple Harmonic Motion Activity Partner 1 Pulls the Paper at CONSTANT Velocity Partner 2 Traces Bob’s Motion with Pencil

Simple Harmonic Motion Activity Look at the Drawing. Do the Following: Measure the Wavelength, . Label it. Measure the Amplitude, A. Label it. Label the crest and the trough Label the nodes Time 3 full periods of your pendulum (use watch or cell phone) , then divide that time by 3 to find the period, T. Record. Calculate the frequency, f (f=1/T). Write your names on the paper & turn in.

Periodic Motion A spring-mass system (also known as a mass-spring system) at equlibrium compressed stretched Spring Masses horizontal x x

Periodic Motion All three diagrams show a snapshot in time of a moving mass on a spring compressed at equilibrium stretched PEe = ½ k(x)2 k = spring constant (N/m) units: Joules x = displacement from equilibrium position Spring Masses vertical Elastic Potential Energy x x x x

Conservation of Energy Vocabulary: spring masses Conservation of Energy Kinetic Energy: KE = ½ mv2 Hooke’s Law Force: F = -k(x) Periodic Motion Oscillate – to move back and forth in a periodic motion As the mass attached to the spring oscillates, ENERGY is TRANSFORMED from Potential to Kinetic to Potential. F = max  PEe = max KE = 0 F = 0 PEe = 0 KE = max F = max x inertia keeps the mass moving x

Conservation of Energy Vocabulary: spring masses Conservation of Energy Kinetic Energy: KE = ½ mv2 Hooke’s Law Force: F = -k(x) Periodic Motion Which Direction will the mass move next? F = max  PEe = max KE = 0 F = 0 PEe = 0 KE = max F = max x x

Period T Kinetic Energy: KE = ½ mv2 Force: F = -k(x) spring masses Period T Kinetic Energy: KE = ½ mv2 Force: F = -k(x) Periodic Motion Period, T, is the time (seconds) for 1 complete oscillation x x

pendulums L (meters) Period g = 9.8 m/s2 T Periodic Motion Period, T, is the time (seconds) for 1 complete oscillation L (meters) g = 9.8 m/s2

moving at equilibrium position pendulums Periodic Motion All three diagrams show a snapshot in time of a moving pendulum bob hmax v=0 PEg = max KE = 0 hmax v=0 PEg = max KE =0 h0 v=max PEg = 0 KE = max moving at equilibrium position

END OF LECTURE