Physics 121, Sections 9, 10, 11, and 12 Lecture 10 Today's Topics Homework 4: Due Friday Sept 30@ 6: 00PM Ch4:#52,57,58,59,60,65,80,84,87,and90. Chapter 5: Rotation Angular variables Centripetal acceleration Kepler's laws Physics 121: Lecture 10, Pg 1
Physics 121: Lecture 10, Pg 1 Physics 121, Sections 9, 10, 11, and 12 Lecture 10 Today’s Topics: Homework 4: Due Friday Sept. 30 @ 6:00PM Ch.4: # 52, 57, 58, 59, 60, 65, 80, 84, 87, and 90. Chapter 5: Rotation Angular variables Centripetal acceleration Kepler’s laws
Chapter 5 Uniform circular Motion What does it mean How do we describe it What can we learn about it Physics 121: Lecture 10, Pg 2
Physics 121: Lecture 10, Pg 2 Chapter 5 Uniform Circular Motion What does it mean ? How do we describe it ? What can we learn about it ?
Review displacement, velocity, acceleration 3-D Kinematics: vector equations dr/dt a= d2r/dt2 th Velocity △r/△t dr/ dt △v Acceleration a dy/ at Physics 121: Lecture 10, Pg 3
Physics 121: Lecture 10, Pg 3 Review ( displacement, velocity, acceleration ) Velocity : Acceleration : a = dv / dt 3-D Kinematics : vector equations: r = r(t) v = dr / dt a = d2 r / dt2 v = dr / dt vav = r / t aav = v / t v2 -v1 v v2 y x path v1
General 3-D motion with non -zero acceleration path a au t a a a+0 because either or both change in magnitude of v atO change in direction of V 0 Uniform Circular Motion is one specific case of this Animation Physics 121: Lecture 10, Pg 4
Physics 121: Lecture 10, Pg 4 General 3-D motion with non-zero acceleration: Uniform Circular Motion is one specific case of this : a v path t a a a = 0 because either or both: -> change in magnitude of v -> change in direction of v a = 0 a = 0 a = a + a Animation
What is Uniform Circular Motion (UCM)? Motion in a circle with Constant Radius r a(x,y) Constant Speed v=v R 0 acceleration con Physics 121: Lecture 10, Pg 5
Physics 121: Lecture 10, Pg 5 What is Uniform Circular Motion (UCM) ? Motion in a circle with: Constant Radius R Constant Speed v = |v| acceleration ? R v x y (x,y) a = 0 a a = const