sy06_sept24_07hc (1) - Physics 207: Lecture 6, Pg 1 Physics...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Physics 207: Lecture 6, Pg 1 Physics 207, Physics 207, Lecture 6, Sept. 24 Lecture 6, Sept. 24 Agenda: Agenda: Assignment: For Wednesday read Chapter 7 Assignment: For Wednesday read Chapter 7 MP Problem Set 3 due Wednesday MP Problem Set 3 due Wednesday MP Problem Set 4 available soon MP Problem Set 4 available soon MidTerm Thursday, Oct. 4, Chapters 1-7, 90 minutes, 7:15-8:45 PM MidTerm Thursday, Oct. 4, Chapters 1-7, 90 minutes, 7:15-8:45 PM Chapter 5 Chapter 5 Friction (a external force that opposes motion) Chapter 6 (Dynamics II) Motion in two (or three dimensions) Frames of reference Physics 207: Lecture 6, Pg 2 Friction... Friction... Friction is caused by the microscopic interactions between the two surfaces: Physics 207: Lecture 6, Pg 3 A special contact force, friction A special contact force, friction What does it do? It opposes motion ! Parallel to a surface Perpendicular to a surface N Normal force How do we characterize this in terms we have learned? A resulting force in a direction opposite to the direction of motion (actual or implied )! m a F APPLIED f FRICTI ON m g N i j j Physics 207: Lecture 6, Pg 4 Sliding Friction (i.e., with motion) Sliding Friction (i.e., with motion) Direction: A force vector to the normal force vector N N Magnitude: | f f K | is proportional to the magnitude of | N N | | f f K | = K | N N | ( = K | m g g | in the previous example) Physics 207: Lecture 6, Pg 5 Case study ... big F Case study ... big F Dynamics: x-axis i : ma x = F- K N y-axis j : ma y = 0 = N mg or N = mg so F- K m g = m a x m ax F m g N i j j K mg v f k f k Physics 207: Lecture 6, Pg 6 Case study ... little F Case study ... little F Dynamics: x-axis i : ma x = F- K N y-axis j : ma y = 0 = N mg or N = mg so F- K m g = m a x m a x F m g N i j j K mg v f k f k Physics 207: Lecture 6, Pg 7 Static Friction... Static Friction... F F applied m g g N N i j j f S So far we have considered friction acting when something has a non-zero velocity We also know that it acts in fixed or static systems: In these cases, the force provided by friction depends on the forces applied on the system (magnitude: f s s N ) Opposes motion that would occur if s were zero Physics 207: Lecture 6, Pg 8 Static Friction... Static Friction... Just like in the sliding case except a = 0 . i : F applied- f S = j : N = mg F F applied applied m g g N N i j j f S While the block is static: f S = F applied (unlike kinetic friction) Physics 207: Lecture 6, Pg 9 Static Friction... Static Friction... F m g N i j j f S The maximum possible force that the friction between two objects can provide is f MAX = S N , where s is the coefficient of static friction ....
View Full Document

Page1 / 55

sy06_sept24_07hc (1) - Physics 207: Lecture 6, Pg 1 Physics...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online