Summary

• Collisions
• Center of mass
• Rotation variables

• Written Quiz    Timer
  
  
• Reading Quiz



• Rotation
  • relation between linear and angular quantities
  • demonstration applet
    Example #1
    
  • kinematics
    Example #2
    
  
  
  
  

Walker4e
Reading quiz Two children ride on a merry-go-round, with child 1 at a greater distance from the axis of rotation than child 2. The angular speed of child 1 is _____ the angular speed of child 2.
A. greater than
B. less than
C. the same as
Answer















sj6 10.17
A disc rotates at 1200 rev/min about its central axis. What is the linear speed of a point 3.0 cm from its center?
A. 60 cm/s
B. 3.77 m/s
C. 10.5 m/s
D. 23.2 m/s
Answer















sj6 10.6
A centrifuge rotates at 3600 rev/min when it is suddenly turned off, spinning 50 times before coming to rest. What is the constant angular acceleration α during spin down?
A. −7.54 rad/s²
B. −1420 rad/s²
C. −377 rad/s²
D. −226 rad/s²
Answer































 



C. the same as


Because the merry-go-round rotates as a single solid object, the angular speed of every point on its surface is exactly the same. The linear speed of child 1, however, is greater than the linear speed of child 2.




















 



B. 3.77 m/s





















 



D. −226 rad/s²