1 / 10

Forces & Newton’s Laws of Motion

Forces & Newton’s Laws of Motion. Chapter 4 (friction). Static Friction that helps keep objects still against forces. Greater than kinetic. Changes size and only does enough to prevent motion, no more. Kinetic Friction of movement. Remains a constant value once an object is moving.

denzel
Download Presentation

Forces & Newton’s Laws of Motion

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. Forces & Newton’s Laws of Motion Chapter 4 (friction)

  2. Static Friction that helps keep objects still against forces. Greater than kinetic. Changes size and only does enough to prevent motion, no more. Kinetic Friction of movement. Remains a constant value once an object is moving. Two Types of Friction

  3. Friction • Depends only on the surfaces, not on velocity • Depends on two things, normal force of the object and the combination of surfaces • Coefficient of friction, µ equals the ratio of frictional force to normal force.

  4. What if . . . ? • FA < Ff • FA = Ff • FA > Ff • Ff is NOT an “applied” force!!

  5. Example #10 What is the acceleration of a 30 kg crate if the frictional force is 10 N and the object has a 15 N force applied to it? Try this problem again but the crate is 30 N.

  6. Example #11A A 52 N sled is pulled across a cement sidewalk at constant speed. A horizontal force of 36 N is exerted. What is the coefficient of friction between the metal runners and the cement?

  7. Example #11B Now the sled runs on packed snow where the coefficient of friction is 0.12. If a 650 N person sits on the sled, what is the applied force needed to move it at constant speed?

  8. Example #12 A penguin slides across the ice 15 m to a stop. The coefficient of friction between the penguin and the ice is 0.01. How fast was the penguin going initially?

  9. Example #13 What coefficient of friction is needed to keep the system at equilibrium? m1=4 kg =? m2=3 kg

  10. Example #14 What is the acceleration of the system shown below? What is the tension in the cable? m1=4 kg =0.2 m2=3 kg

More Related