1 / 15

UNIT 4 Work, Energy, and Power

UNIT 4 Work, Energy, and Power. ConcepTest 6.3 Force and Work. 1) one force 2) two forces 3) three forces 4) four forces 5) no forces are doing work. A box is being pulled up a rough incline by a rope connected to a pulley. How many forces are doing work on the box?. displacement.

kevina
Download Presentation

UNIT 4 Work, Energy, and Power

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. UNIT 4Work, Energy, and Power

  2. ConcepTest 6.3Force and Work 1) one force 2) two forces 3) three forces 4) four forces 5) no forces are doing work A box is being pulled up a rough incline by a rope connected to a pulley. How many forces are doing work on the box?

  3. displacement N T f mg ConcepTest 6.3Force and Work 1) one force 2) two forces 3) three forces 4) four forces 5) no forces are doing work A box is being pulled up a rough incline by a rope connected to a pulley. How many forces are doing work on the box? Any force not perpendicularto the motion will do work: N does no work T does positive work f does negative work mg does negative work

  4. Tuesday November 8th KINETIC ENERGY

  5. TODAY’S AGENDA Tuesday, November 8 • Kinetic Energy • Hw: Practice B (All) p165 UPCOMING… • Wed: Potential Energy • Thur: Conservation of Mechanical Energy

  6. Section 2 Energy Chapter 5 Kinetic Energy • Kinetic Energy The energy of an object that is due to the object’s motion is called kinetic energy. • Kinetic energy depends on speed and mass.

  7. Section 2 Energy Chapter 5 Kinetic Energy, continued • Work-Kinetic Energy Theorem • The net work done by all the forces acting on an object is equal to the change in the object’s kinetic energy. • The net work done on a body equals its change in kinetic energy. Wnet= ∆KE net work = change in kinetic energy

  8. Section 2 Energy Chapter 5 Sample Problem Work-Kinetic Energy Theorem On a frozen pond, a person kicks a 10.0 kg sled, giving it an initial speed of 2.2 m/s. How far does the sled move if the coefficient of kinetic friction between the sled and the ice is 0.10?

  9. Section 2 Energy Chapter 5 Sample Problem, continued Work-Kinetic Energy Theorem 1. Define Given: m = 10.0 kg vi = 2.2 m/s vf = 0 m/s µk = 0.10 Unknown: d = ?

  10. Section 2 Energy Chapter 5 Sample Problem, continued Work-Kinetic Energy Theorem 2. Plan Choose an equation or situation: This problem can be solved using the definition of work and the work-kinetic energy theorem. Wnet = Fnetdcosq The net work done on the sled is provided by the force of kinetic friction. Wnet = Fkdcosq = µkmgdcosq

  11. Section 2 Energy Chapter 5 Sample Problem, continued Work-Kinetic Energy Theorem 2. Plan, continued The force of kinetic friction is in the direction opposite d, q = 180°. Because the sled comes to rest, the final kinetic energy is zero. Wnet = ∆KE = KEf - KEi = –(1/2)mvi2 Use the work-kinetic energy theorem, and solve for d.

  12. Section 2 Energy Chapter 5 Sample Problem, continued Work-Kinetic Energy Theorem 3. Calculate Substitute values into the equation:

  13. END

More Related