1 / 13

Chapter 5 Notes

Chapter 5 Notes. Circular Motion and Gravitation. 5-1 Kinematics of Uniform Circular Motion. Uniform circular motion - An object that moves in a circle at a constant speed (v). The magnitude of the velocity remains constant, but the direction of the velocity is constantly changing.

mreza
Download Presentation

Chapter 5 Notes

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 5 Notes Circular Motion and Gravitation

  2. 5-1 Kinematics of Uniform Circular Motion • Uniform circular motion - An object that moves in a circle at a constant speed (v). • The magnitude of the velocity remains constant, but the direction of the velocity is constantly changing. • Acceleration = change in velocity / change in time • Object revolving in a circle is continuously accelerating Chapter 5

  3. Review of centripetal acceleration • pg. 113 Fig 5-1 & 5-2 • Velocity points tangent to circle • Change in velocity - points to center of circle • Centripetal acceleration - “center seeking” acceleration • Centripetal acceleration = ar Chapter 5

  4. ar = v2/r • An object moving in a circle of radius r with a constant speed v has an acceleration whose direction is toward the center of the circle and whose magnitude is ar = v2/r. • Velocity and acceleration vectors are perpendicular to each other at every point in the path for uniform circular motion. Chapter 5

  5. Frequency (f) - number of revolutions per second • Period (T) - time required to complete one revolution • T = 1/f • For an object revolving in a circle at constant speed v: v=2r/T • Example 5-1 & 5-2 Chapter 5

  6. 5-2 Dynamics of Uniform Circular Motion • Newton F=ma • Object moving in a circle must be acted on by a force Fr=mar=mv2/r • Net force must be directed toward the center of the circle. • Centripetal force - force directed towards center of circle Chapter 5

  7. Centrifugal force vs. centripetal force • pg. 116 Read Paragraph out loud • Examples 5-3,4,5 & 6 pg. 117-119 Chapter 5

  8. 5-8 Satellites and Weightlessness • Satellite - put into circular orbit by accelerating tangentially using rockets • too fast - gravity will not confine it • too slow - gravity will cause it to fall back to earth Chapter 5

  9. What keeps a satellite in space? • High speed, if it stopped moving it would fall to earth • Satellite is falling, but high tangential speed keeps it from falling to earth Chapter 5

  10. satellite acceleration = ar = v2/r • force accelerating object is earth’s gravity F= mar • GmmE/r2= mv2/r • m = mass satellite • r = rE + height satellite • Example 5-15 pg. 130 Chapter 5

  11. Weightlessness • elevator - rest • F= ma W-mg=0 W=mg • for acceleration upward = positive • accelerate upward at a : F= ma W-mg = ma W=ma +mg • downward a is negative, W is less than mg Chapter 5

  12. Weightlessness (cont.) • upward a=1/2g W=3/2mg experience 3/2 g’s acceleration • downward a=-1/2g W=1/2mg experience 1/2g acceleration • if downward acceleration = free fall = g • W=mg-ma W=mg-mg=0 • therefore, you feel weightless - “apparent weightlessness” • Apparent weightlessness on earth - ski jump, trampoline Chapter 5

  13. Satellites fall toward earth, only force acting on it is gravity • Out in space far from the earth - true weightlessness occurs • gravity pull from other planets is extremely small due to large distances away • Prolonged weightlessness - red blood cells diminish, bones lose calcium and become brittle, muscles lose their tone. Chapter 5

More Related