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Informal sessions:

o Tu 3:30-4:20pm, RAS 218;

o Fri 4-4:50pm, ECJ 1.204.

Lecture 14

Revisit path independent properties:

• Work against gravity from A to B
• Network from A to B

Potential energy stored in a spring

Exercises on W-E theorem: System include a spring

Conservative force F^c and potential energy function U

• From F^c to U
• From U to F^c

Reminders:

o Read chapter 7-8, start working on HW6

o Reminder: Tuesday’s Instructor’s informal session (time and place, see above)

o Exam1 grading is essentially completed. If your exam1 record still has a problem, please email Matt and cc a copy to me asap.

o How to determine your exam letter grade?

Definition: Scaled score = (Rawscore – Average) x 100/std +500, where std=standard deviation.

For the exam, you have made two letter-grades.

§ The first letter grade is based on the percent-score-cutoffs.

They are: 40%, 55%, 75% and 90% for D, C, B and A respectively;

§ The second letter-grade is based on the scaled-score-cutoffs.

They are: 400, 450, 525, and 600 for D, C, B and A respectively.

If these two letter-grades are not the same, the better of the two is what you have made.