Lecture 1: Wave Phenomena, Part 1

A surfer braves the monster waves that form in an area on the north shore of Maui called “Jaws”, where about 12 times a year, the conditions are just right to produce some of the largest waves in the world: the shape of the beach sculpts the swells that originate from as far as Alaska into 40- to 70-foot [12- to 21-meter] walls of water.

Steven Kornreich www.beachlook.com

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“Jaws”, Maui.

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Review of Simple Harmonic Motion Equlibrium Position

The position at which all forces acting on an object sum to zero.

Displacement Change in the position of an

object with respect to the equilibrium position.

Restoring Force Force that acts on the object

that tends to make it move towards the Eq. position.

Simple Harmonic Motion When Restoring force

proportional to the Displacement

xF k x6666666666666666666666666666

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Review of Simple Harmonic MotionCont.

If we pull the mass and let go, it will begin oscillating.

It will reach a maximum displacement in each oscilation (Amplitude A)

It will reach the same point with the same velocity after a given amount of time (Period T)

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Displacement as a function of time

y(t) = A sin (2 t/T + )

y=Displacement

A=AmplitudeT=Period =phase

t

y

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Transverse Waves

Particle moves up-down.

Disturbance moves to the right

Particle motion and wave motion are at right angles.

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Longitudinal Waves

Particle moves right-left

Disturbance moves to the right.

Particle motion is along the same direction as wave propagation.

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Visualizing the wave function.Displacement of a slinky.

time

space

disp

lace

men

t

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Using 2 1-D plots.