1 / 10

Friction

Friction. A force that opposes motion. Causes Of Friction. Matter is not as smooth on its surface as it appears to be; tiny irregularities get “stuck” on one another On very smooth surfaces, the atoms can become so close that there are electrical forces acting between them

elke
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 A force that opposes motion

  2. Causes Of Friction • Matter is not as smooth on its surface as it appears to be; tiny irregularities get “stuck” on one another • On very smooth surfaces, the atoms can become so close that there are electrical forces acting between them • Sliding objects often experience “jerky” motion as bonds or “jags” are broken

  3. Types of Friction • Kinetic Friction – friction of moving objects • Amount of kinetic friction depends on - nature of surfaces (type of material) - normal force pushing surfaces together • Does not depend on the amount of surface area • There are different types of kinetic friction: sliding and rolling

  4. Proportionality • Ff = μkFN • μkis called the coefficient of kinetic friction • μk depends on the nature of the two surfaces in contact • More friction, higher μk

  5. Example • What frictional force will a .75kg waxed ski experience as it slides on wet snow? Draw a free body diagram

  6. Static Friction • Friction that must be overcome to start motion • It is higher than kinetic friction • μs = Ff/ FN

  7. Example • A 10.0 kg box rests on the floor. The coefficient of static friction is .40 and kinetic friction is .30. Find the force of friction acting on the box if it is pushed by a) 0 N b) 10 N c) 20 N d) 38 N e) 40 N

  8. Question • Your little sister wants a ride on her sled. Will you use more force if you push or pull her? Assume the same angle in each case.

More Related