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Lecture 12

Work energy theorem:

• Dfn: Work. W=Fs_||=Fs cos q= Fês= F_||s
• Dfn: Potential energy. Gravitational potential energy at y = Work done in lifting m from 0 to y.
• U(y)=W_0®y=mgy
• Work energy theorem
• Demo

Uniform circular motion (cont’d)

• Cyclone
• Ferris Wheel
• Conic pendulum
• Speed at a banked curve:

To do:

o Review chapters 5-6.

o Preview chapters 7-8

o Start working on hw5.

The grading of exam1 is done.

o Quest-support team asks students to check his/her problem-by-problem grading of the exam1 carefully. Please email Matt (also cc a copy to me) if you have found any irregularity.

o Usually when regrading occurs some change in the grade distribution is expected which could lead to some change in the scaled score.

You have made two letter-grades for the exam.

1. The “letter grade” based on the percent-score-cutoffs,

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

2. The “letter-grade prime” based on scaled-score-cutoffs

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

If your two letter-grades are not the same, the better is the one you have made.

Please record your exam-scaled score. we will revert to the original raw-score display by the end of this week.