Day 23 - Homework Session

Announcements

  • Homework 3 is graded
  • Midterm 1 is still being graded
    • Re: Problem 2 HOLY CRAP YOU ALL ARE AMAZING
  • Homework 5 is due tonight
  • Homework 6 is due next Friday
  • Danny will be out next Wednesday
    • Class will be on zoom (usual link)

Reminders

We solved the damped harmonic oscillator equation:

We chose a solution (ansatz) of the form

and computed the roots of the characteristic equation:

We found the roots to be:

Weak Damping

We found that when , the roots are complex:

This means that the solution is oscillatory:

The solution is a damped oscillation with frequency .

Strong Damping

When , the roots are real:

This means that the solution is not oscillatory:

where and .

The solution is the sum of two exponentials with different decay rates.

Critical Damping

When , the roots are real and equal (repeated roots):

This means that the solution is not oscillatory, but also that our ansatz is not sufficient. The correct form of the solution is:

In most cases, we will work with weak damping.