1 / 43

Chapter 12

Chapter 12. Section 1 & 2. Terms to Know. 1)Periodic motion simple harmonic motion: The motion that results when an object that is not at equilibrium (F net = 0) tries to return to its equilibrium. 2)period (T): the time taken for a cycle 3) frequency ( f ) = # of cycles per second = 1/T

alena
Download Presentation

Chapter 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 12 Section 1 & 2

  2. Terms to Know 1)Periodic motion • simple harmonic motion: The motion that results when an object that is not at equilibrium (Fnet = 0) tries to return to its equilibrium

  3. 2)period (T): the time taken for a cycle 3) frequency (f) = # of cycles per second = 1/T 4)amplitude (A) = the max distance from equilibrium

  4. Introduction to Hooke’s Law • khanacademy - Hooke's Law

  5. Hooke’s Law • F = Restoring force (N) • x = displacement (m) • k = spring constant (N∙m-1) • F = -kx (F and x are in opposite directions)

  6. Determining k

  7. 1 dyne = 1 g·cm/s² = 10−5 kg·m/s² = 10−5 N k =? (2) How much work is done by the spring when it is stretched to 10cm?

  8. Limitation in Hooke’s Law

  9. PE in a Spring

  10. KE and PE in Spring

  11. Example 12A, Pg 440 If a mass of 0.55 kg attached to a vertical spring stretches the spring 2.0 cm from its equilibrium (= unstretched) position, what is the spring constant?

  12. Example A spring stretches by 18 cm when a bag of potatoes weighing 56 N is suspended from its end. • Determine the spring constant. • How much elastic potential energy is stored in the spring when it is stretched this far?

  13. Harmonic Motion in Pendulum • Pendulum Motion • acceleration and velocity • http://www.cabrillo.edu/~jmccullough/Applets/Flash/Mechanics/PendulumForces.swf • tension, weight, and net force

  14. Looking at a, v, forces on a pendulum again

  15. Forces acting on a Pendulum

  16. KE and PE in Pendulum

  17. KE + PE = ME

  18. Period of a Pendulum • T = 1/f • For the period derivation • The mass and amplitude do not change the period!

  19. Foucault Pendulum

  20. Sample Problem 12B, Pg 448 You need to know the height of a tower, but darkness obscures the ceiling. You note that a pendulum extending from the ceiling almost touches the floor and that its period is 12 s. How tall is the tower?

  21. Example A pendulum with a length of 36.9 cm has a period of 1.22 s. What is the acceleration due to gravity?

  22. Period of a Spring

  23. Sample Problem 12C, Pg 450 The body of a 1275 kg car is supported by four springs, each of which as a spring constant of 2.0×104 N/m. Two people riding in the car have a combined mass of 153 kg. Find the period of vibration of the car when it is driven over a pothole in the road.

  24. Resonance

  25. Wave Properties • Wave: one of two ways to carry energy • Matter is the other way • Mechanical waves: require a medium through which waves propagates • Medium = rope, water, spring, air • Two types: transverse and longitudinal *Play RealPlayer on two types of waves

  26. More Wave Animation • http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html

  27. Describing a Wave • amplitude, A • wavelength, λ (lambda) • period, T (sec) • frequency, f (cycles per sec = sec-1 = Hz) • speed, v • phase • crest, compression • trough, rarefaction

  28. T, f, & v

  29. Example A sound wave has a frequency of 192 Hz and travels the length of a football field, 91.4 m, in 0.271 s. • the speed? • the wavelength? • the period? • If the frequency was changed to 442 Hz, new wavelength? New period?

  30. Terms to Know • incident wave • transmitted wave • reflected wave

  31. Wave Behavior • At a free end • At a fixed boundary • At the boundary with another medium • interference • constructive • destructive • Standing waves • Refraction

  32. Wave at a free end • Reflection of a Pulse at a Free End

  33. Waves at a fixed boundary • Reflection of a Pulse at a Fixed End

  34. Waves through different medium • Characteristics of a Transmitted Pulse

  35. Interference • How two or more waves are interacting • Each wave affect the medium independently • Waves algebraically combine to form a new wave - Principle of superposition • Constructive interference • Destructive interference (Show Realplayer)

  36. Constructive Interference(Waves are in phase)

  37. Destructive Interference(Waves are out of phase) • B • A+B A

  38. Standing Wave • (Show RealPlayer)

  39. Refraction • A profound effect of light waves • Bending the light waves when entering a different medium, results in the change of speed.

More Related