{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

sy11_oct10_07hc - "Professor Goddard does not know the...

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

View Full Document Right Arrow Icon
Physics 207: Lecture 11, Pg 1 "Professor Goddard does not know the relation between action and reaction and the need to have something better than a vacuum against which to react. He seems to lack the basic knowledge ladled out daily in high schools." New York Times editorial, 1921, about Robert Goddard's revolutionary rocket work . "Correction: It is now definitely established that a rocket can function in a vacuum. The 'Times' regrets the error." New York Times editorial, July 1969.
Image of page 1

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

View Full Document Right Arrow Icon
Physics 207: Lecture 11, Pg 2 Partial Survey Summary Partial Survey Summary Lecture Too many slides that come too quickly More problem solving on white board Too much time spent on “interactive problems but, when used, not enough time spent on explanation More demos
Image of page 2
Physics 207: Lecture 11, Pg 3 Another example with friction and pulley Another example with friction and pulley Three 1 kg masses are connected by two strings as shown below. There is friction between the stacked masses but the table top is frictionless. Assume the pulleys are massless and frictionless. What is T 1 ? M M M T 1 friction coefficients μ s =0.4 and μ k =0.2
Image of page 3

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

View Full Document Right Arrow Icon
Physics 207: Lecture 11, Pg 4 Physics 207, Physics 207, Lecture 11, Oct. 10 Lecture 11, Oct. 10 Agenda: Agenda: Assignment: Assignment: Read through Chapter 10 MP HW5 available now, due Wednesday 10/17, 11:59 PM Chapter 9: Momentum & Impulse Chapter 9: Momentum & Impulse Momentum conservation Collisions Impulse
Image of page 4
Physics 207: Lecture 11, Pg 5 Impulse & Linear Momentum Impulse & Linear Momentum Transition from forces to conservation laws Transition from forces to conservation laws Newton’s Laws Conservation Laws Conservation Laws Newton’s Laws They are different faces of the same physics phenomenon. NOTE: We already have studied “impulse” and “momentum” but we have not explicitly named them as such
Image of page 5

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

View Full Document Right Arrow Icon
Physics 207: Lecture 11, Pg 6 Lecture 11, Example 1 Lecture 11, Example 1 A 2 kg cart initially at rest on frictionless horizontal surface is acted on by a 10 N horizontal force along the positive x-axis for 2 seconds what is the final velocity? F is in the x-direction F = ma so a = F/m = 5 m/s 2 v = v 0 + a t = 0 m/s + 2 x 5 m/s = 10 m/s (+x-direction) What if the mass had been 4 kg? What is the new final velocity?
Image of page 6
Physics 207: Lecture 11, Pg 7 Twice the mass Twice the mass Same force Same time Half the acceleration Half the velocity ! ( 5 m/s )
Image of page 7

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

View Full Document Right Arrow Icon
Physics 207: Lecture 11, Pg 8 Example 1 Example 1 Notice that the final velocity in this case is inversely proportional to the mass (i.e., if thrice the mass….one-third the velocity). It would seems that mass times the velocity always gives the same value. (Here is it always 20 kg m/s.)
Image of page 8
Physics 207: Lecture 11, Pg 9 Example 1 Example 1 There many situations in which the product of “mass times velocity” is a constant and so we give a special name, “momentum” and associate it with a conservation law.
Image of page 9

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

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern