# Oscillations, continued Lecture 31 Wednesday, November 19.

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Oscillations, continued Lecture 31 Wednesday, November 19

Workbook problems due Today WB 10.5, problems 14-25

Workbook Problems due Friday Problems 14-1 through 8, pages 14-1 -- 5

Quiz A student places her 500g physics textbook on a frictionless table. She pushes the book against a spring 4.00cm and then releases the book. What is the book’s speed as it slides away? The spring constant is k = 1250 N/m.

Equilibrium and Oscillation Frequency and Period

Simple Harmonic Motion Linear restoring force— – Example, mass on a spring – Set y=0 at equilibrium point: –

θ w cos θ w w sin θ T

Simple Pendulum Find the angular frequency is

Description of motion

a)At what time(s) is particle moving right at maximum speed? b)At what time(s) is particle moving right at maximum speed? c)At what time(s) is the speed zero?

Problem 14:7 An air-track glider is attached to a spring. The glider is pulled to the right and released from rest at t=0s. It then oscillates with T=2.0s and v max = 40cm/s a)A=? b)x(t=0.25s) = ?

Problem 14.7

Energy in Simple Harmonic Motion

Pendulum Point mass on a string

Physical Pendulum θ Center of gravityL d

Damped Harmonic Motion Friction rears its ugly head!

Damped Harmonic Motion

Problem 14.15 A) When the displacement of a mass on a spring is ½A, what fraction of the mechanical energy is kinetic energy and what fraction is potential?

B) At what displacement as a fraction of A, is the energy half kinetic and half potential?

Problem 14.30 The center of gravity of a lower leg of a cadaver which had a mass of 5kg was located 18cm from the knee. When pivoted at the knee, the oscillation frequency was 1.6Hz. What is the moment of inertia of the lower leg?

Problem 14.30