Physics 207: Lecture 9, Pg 1Physics 207, Physics 207, Lecture 9,Lecture 9, Oct 5 Oct 5 ‘‘0909TODAYTODAYCircular motion: 4.5, 4.6, 8.2, 8.3Circular motion: 4.5, 4.6, 8.2, 8.3Momentum: 9.1, 9.2Momentum: 9.1, 9.2Exams to be returned in discussionExams to be returned in discussion this weekthis weekAssignments:Assignments: This week’s lab: Equilibrium Force (M-2) & Circular Motion (M-6) HW 5 due Friday, Oct 9, 6 pmPhysics 207: Lecture 9, Pg 2Circular MotionCircular Motion Car driving around curved track Planets orbiting Sun (actually elliptical motion) Electrons orbiting nucleus (simplest “Bohr model” for atom)Physics 207: Lecture 9, Pg 3Prof. Timbie whirls a tennis ball around hisProf. Timbie whirls a tennis ball around hishead on a string. If the string breaks, thehead on a string. If the string breaks, theball:ball:A. Continues to follow a circular pathB. Follows a straight lineC. Follows a slightly curved pathPhysics 207: Lecture 9, Pg 4Physics 207: Lecture 9, Pg 5Physics 207: Lecture 9, Pg 6Physics 207: Lecture 9, Pg 7Physics 207: Lecture 9, Pg 8Physics 207: Lecture 9, Pg 9Physics 207: Lecture 9, Pg 10Physics 207: Lecture 9, Pg 11Physics 207: Lecture 9, Pg 12Physics 207: Lecture 9, Pg 13What makes a rocket take off?What makes a rocket take off?A. Newton’s third lawB. Conservation of MomentumC. Hot gases push against airPhysics 207: Lecture 9, Pg 14"Professor Goddard does not know the relation betweenaction and reaction and the need to have something betterthan a vacuum against which to react. He seems to lackthe basic knowledge ladled out daily in high schools."New York Times editorial, 1921, about Robert Goddard'srevolutionary rocket work."Correction: It is now definitelyestablished that a rocket canfunction in a vacuum.The 'Times' regrets the error."New York Times editorial, July 1969.Physics 207: Lecture 9, Pg 15 Newton’s Third
View Full Document
Unlocking...