Homework Example: Student Responses

1. Why does the system start with a large natural component?

2. How is motion at the drive frequency sustained at long times?

 

Misconceptions

  • the larger the drive, the sooner the natural component is removed.

  • with little damping, only the drive acts to shape the motion.

  • when the oscillation frequency equals the drive frequency, there is no damping.

  • with damping, the object will continue to oscillate only if the drive frequency is set to the natural frequency.

 

Insights

  • the damping depends on velocity and doesn't act until the system is in motion.

  • since the drive acts over time, the motion is natural until the drive has a chance to shape it.

  • motion at the drive frequency lasts a long time because drive energy is continually fed into the system to counter the damping loss.