{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Phy107Lect20

# Phy107Lect20 - HW#7 Chapter 11 Concept 2 6,14 20 32 34...

This preview shows pages 1–11. Sign up to view the full content.

Fri. Oct 22 Phy107 Lecture 20 Hour Exam 2 : Wednesday, Oct. 27 In-class (1300 Sterling Hall) Twenty multiple-choice questions Will cover: 8.1-8.6 (Light and E&M) 9.1-9.5 (E&M waves and color) 10, 11 (Relativity) You should bring Your student ID 1 page notes, written double sided – Calculator Pencil for marking answer sheet HW#7: Chapter 11 Concept: 2, 6,14, 20, 32, 34 Problems: 4, 6

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

View Full Document
Fri. Oct 22 Phy107 Lecture 20 General Relativity and Gravity Special Relativity deals with inertial reference frames , frames moving with a constant relative velocity. It has some rather unusual predictions Time dilation Length contraction Mass-energy equivalence These were motivated by thought experiments based on simple postulates. General Relativity also motivated by some simple thoughts about gravity and free-fall.
Fri. Oct 22 Phy107 Lecture 20 The Equivalence Principle Led Einstein to postulate the Equivalence Principle. Clip from Einstein Nova special.

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

View Full Document
Fri. Oct 22 Phy107 Lecture 20 Equivalence principle Accelerating reference frames are indistinguishable from a gravitational force.
Fri. Oct 22 Phy107 Lecture 20 Try some experiments Constant velocity Cannot do any experiment to distinguish accelerating frame from gravitational field t=0 t=t o t=2t o Floor accelerates upward to meet ball Constant accel. t=0 t=t o t=2t o

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

View Full Document
Fri. Oct 22 Phy107 Lecture 20 Light follows the same path Path of light beam in our frame Velocity = v t =0 Velocity = v + at o t = t o Path of light beam in accelerating frame Velocity = v +2 at o t =2 t o
Fri. Oct 22 Phy107 Lecture 20 Is light bent by gravity? If we can’t distinguish an accelerating reference frame from gravity… and light bends in an accelerating reference frame… then light must bend in a gravitational field But light doesn’t have any mass. How can gravity affect light?

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

View Full Document
Fri. Oct 22 Phy107 Lecture 20 Light travels in a straight line In some ways, the path of light defines a straight line. Surveyors use laser to set heights. Can use a laser level to put up shelves. Seems to move in exactly a straight line. Maybe we are confused about what a straight line is
Fri. Oct 22 Phy107 Lecture 20 What is a straight line? Claim that these are all straight lines

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

View Full Document
Fri. Oct 22 Phy107 Lecture 20 Straight is shortest distance They are the shortest distances determined by wrapping string around a globe. On a globe, they are called ‘great circles’. In general, geodesics. This can be a general definition of straight, and is in fact an intuitive one on curved surfaces It is the one Einstein used for the path of all objects in curved space-time.
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• 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.

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

• 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.

Dana University of Pennsylvania ‘17, Course Hero Intern

• 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.

Jill Tulane University ‘16, Course Hero Intern