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Lecture: 10 Chapter 3 (con’d) (iq07)

1. Four fundamental types of interactions.

2. Gravitational force, F_g (revisit). Beyond spherical balls.

3. Compare electric force Fe with Gravitational force F_g

4. Building blocks of matter

5. Neutral matter. Charging through rubbing the surfaces

6. The ratio: F_e/F_g.

Announcement and Reminders:

1. Midterm1: Class average 68%. I am pleased with the overall performance of the class.

2. How to determine the letter grade you made for this exam?

Use the percent-score cutoff and the scaled score cutoff to determine your letter grades.

o ps-letter grade

o ss-letter grade.

If your two letter grades are different, the better of the two is the letter grade you have made for this exam.

3. You should work through all the problems you have missed. If you did not do as well as you had expected, you are welcome to see me to discuss your exam performance and look for ways to improve your study habit.

4. Please also consider to consult Matt, the TA, and your designated LA.

5. Errata: See the last link under MI-interaction curriculum.