Announcements

1
Announcements

• New homework
• (Ch. 8, Problems 47 50)
• 8.40 10.9 rad/s
• Office hours
• MW 10-11 am
• TRF 2-3 pm
• Tutorial Learning Center
• M 8 - 11 am, 530-7pm
• W 8 - 11 am, 4 - 7pm
• TR 8 - 9 am, 4 - 7pm
• R 7 - 9 pm new dorm
• F 8 - 11 am

2
Chapter 8

• Rotational Equilibrium Rotational Dynamics
• (Rotational Angular Momentum)

3
Last time

• Rotational Kinetic Energy
• Work-Energy Theorem
• Angular Momentum

4
Demo

• Question How do you test
• Student on rotating platform
• Show that
• Show effect of changing I

5
Serway 8.55

• A cylinder with moment of inertia I1 rotates with
  angular velocity ?0 about a frictionless vertical
  axle. A second cylinder, with moment of inertia
  I2 , initially not rotating, drops onto the first
  cylinder. Since the surfaces are rough, the two
  cylinders eventually reach the same angular speed
  ?.
• Calculate ?.
• Show that kinetic energy is lost in this
  situation, and calculate the ratio of the final
  to the initial kinetic energy.

6
Serway 8.62

• A uniform 10.0 N picture frame is supported as
  shown in figure P8.62.
• Find the tension in the cords and the magnitude
  of the horizontal force at P that are required to
  hold the frame in the position shown.