Tuesday, May 17, 2011

Announcements:

• Exam 1 will be held in class on Thursday instead of Wednesday.
• If you prefer to take this exam on Wednesday, let me know when you want to do so.
• There will be a review session for Exam1 on Wednesday after class (9:30 - 10:00) in Phillips 215.
• Class Participation scores are now posted on Blackboard.
• If your score is less than 100% and you have not missed any days of class, let me know.
• The maximum possible Class Participation score is 110%.
• Remember to take advantage of SI sessions (at 5:00 pm) and my office hour after class if you have questions.
• Responses to student questions and comments from Friday's class can be found below.
• A solution to the Bank Robbery real-world problem will be posted tomorrow.

Suggestions for exam preparation:

1. Practice by taking Exam1 from 2003. (allow 50 minutes to work as if it were an actual exam)
2. Review conceptual questions and answers in back of book. (1 hr.)
3. Review homework problems and textbook examples as needed. (1 hr.)
4. Review class notes and know how to answer in-class exercises. (1 hr.)
5. Study ConcepTest (clicker) questions under Course Documents section of Blackboard. (1 hr)
6. Practice solving additional textbook problems as needed.

Assignments:

• Bank Robbery RWP is due today or tomorrow.
• HW5 is due tonight at midnight.
• Read Chapter 6 and submit HW6 by midnight tomorrow.
• [optional: original RWP for Exam1 - due Thursday at 8:00 am]

Chapter 4:  Motion in Two Dimensions

Ponderable: What were the initial speeds of the balls dropped in class yesterday?

Range of a projectile: Derivation and reflection

Chapter 5:  Newton's Laws of Motion

Definition of mass - measure of inertia, resistance to acceleration; measured in kilograms (kg)
Definition of force - a push or pull, measured in Newtons (N).  1 lb. ~ 4.4 N

Newton's Laws of motion
    1)  Inertia:  A net external force is required to change an object's velocity.
2)  F = ma:    Why does this equation make more sense written:   a = F/m ?
    3)  Action/Reaction:  F₁₂ = -F₂₁   Equal and opposite forces on different objects.

Draw a graph for the acceleration that results from force applied to a mass (a vs. F).  What does the slope represent?
Rocket Cart demo -  Find the acceleration, the final speed, and the force exerted by fire extinguisher.
Definition of weight and "weightlessness":  F_g = w = mg
Ponderable:  How can you reduce your weight?
Ponderable:  How would you know the mass of an object in outer space where there is no gravity?
How much would you weigh on the moon?
Show that objects in free-fall accelerate downward at  a = g.
Normal force is the reaction force that is exerted on an object and perpendicular to a surface. Often Fn = -Fg, but not always.
Free body diagram practice:  Forces on a book