phys 1001: oscillations and waves
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PHYS 1001: Oscillations and Waves. Stream 3&4: Dr Rongkun Zheng Dr Darren Hudson [email protected] [email protected]. Streams 1&2: Dr Helen Johnston Rm 213. Ph : 9036-9259 [email protected]. My research: black holes in binary star systems - PowerPoint PPT PresentationTRANSCRIPT
PHYS 1001: Oscillations and Waves
PHYS 1001:Oscillations and Waves
Stream 3&4: Dr Rongkun ZhengDr Darren [email protected]@sydney.edu.auStreams 1&2: Dr Helen JohnstonRm 213. Ph: [email protected]
My research: black holes in binary star systems supermassive black holes in the centres of galaxies
Module Outline10 LecturesLab + tutorials + assignments Assignment #6 due 7 JuneUniversity Physics, Young & FreedmanCh. 14: Periodic MotionCh. 15: Mechanical WavesCh. 16: Sound and HearingOverviewL1: Intro to Simple Harmonic Motion (SHM)L2: Applications of SHM; Energy of OscillationsL3: Simple and Physical Pendulums; ResonanceL4: Intro to Mechanical WavesL5: Wave Equation and Wave SpeedL6: Interference and SuperpositionL7: Standing Waves; Normal ModesL8: Sound Waves; Perception of SoundL9: Interference; BeatsL10: Doppler Effect; Shock WavesWhat is an oscillation?Any motion that repeats itselfDescribed with reference to an equilibrium positionwhere the net force is zero, and a restoring force which acts to return object to equilibriumCharacterised by:Period (T) or frequency (f) or angular freq ()Amplitude (A)What is an oscillation?14.1Test your understandingConsider five positions of the mass as it oscillates: 1, 2, 3, 4, 5
(1) (2) (3) (4) (5)Where is the acceleration of the block greatest?position 1position 2position 3position 4position 5A mass attached to a spring oscillates back and forth as indicated in the position vs. time plot below.
Test your understandingA mass attached to a spring oscillates back and forth. At point P, the mass haspositive velocity and positive acceleration.positive velocity and negative acceleration.positive velocity and zero acceleration.negative velocity and positive acceleration.negative velocity and negative acceleration.negative velocity and zero acceleration.zero velocity but is accelerating (positively or negatively).zero velocity and zero accelerationSimple Harmonic MotionSuppose the restoring force varies linearly with displacement from equilibrium F(t) = k x(t)Then the displacement, velocity, and acceleration are all sinusoidal functions of timeThis defines Simple Harmonic Motion (SHM)Period/frequency depend only on k and m with = (k/m) (does not depend on amplitude!)14.2
12SHM & circular motionAn object moves with uniform angular velocity in a circle.The projection of the motion onto the x-axis is x(t) = A cos(t + )The projected velocity & acceleration also agree with SHM.Every kind of SHM can be related to a motion around an equivalent reference circle.14.2LECDEM: Ball on edge of bicycle wheelGoddammit, add more material!!!!!! Do some of the end-of-chapter problems, eg.A block on a frictionless table is attached to a wall with a spring. The block is pulled a distance d to the right of its equilibrium position and released from rest. It takes a time t to get back to the equilibrium point.
If instead the mass is pulled a distance 2d to the right and then released from rest, how long will it take to get back to the equilibrium point?dIf instead the mass is pulled a distance 2d to the right and then released from rest, how long will it take to get back to the equilibrium point?twice as longthe square root of two times longerthe samethe square root of two times shortertwice as short
Identical PeriodsDifferent AmplitudesIdentical AmplitudesDifferent PeriodsPeriod and Amplitude14.1Next lectureApplications of SHM
Read 14.114.3