1 / 10

FRICTION

FRICTION. Sliding Friction. Often called kinetic friction A force opposite to direction of motion Due to bumps in surfaces and electric forces. Surface under microscope. F f. Kinetic Friction. Depends on nature of the two surfaces

jeb
Download Presentation

FRICTION

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. FRICTION

  2. Sliding Friction • Often called kinetic friction • A force opposite to direction of motion • Due to bumps in surfaces and electric forces Surface under microscope Ff

  3. Kinetic Friction • Depends on nature of the two surfaces • Directly proportional to the normal force between the surfaces • Ff = mkFN

  4. Coefficient of friction mk • Usually between zero and one • Calculate from Ff / FN • Very low for ice and some other materials

  5. Friction: Good or Bad • Mostly undesirable since reduces useful force and wastes energy • Friction produces heat • Necessary for walking • Necessary for braking

  6. Static Friction • Force to start something moving • Usually larger than kinetic friction for same surfaces • Requires force to be exerted • Before sliding begins, is equal and opposite to applied force • = msFN at breakaway only(otherwise less)

  7. Friction vs Applied Force • Starting with body at rest FA Ff msFN here only Ff = mkFN here 450 FA

  8. Kinetic Friction for Block • Normal force equals weight FN mg Ff = mkFN = mk mg

  9. What is the Frictional Force? • Block on an inclined plane mg

  10. LHP • Sketch large diagrams of the forces involved in the following situations: • A block dragged across the floor • A block sitting on a ramp with no movement • A block being dragged up a ramp

More Related