• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Torsional pendulum, logarithmic decrement

  • Thread starter tone999
  • Start date
1. The problem statement, all variables and given/known data

The amplitude of a torsional vibration decreases so that the amplitude on the 100th cycle is 13% of the the amplitude of the first cycle. Determine the level of damping in terms of the logarithmic decrement.

2. Relevant equations



3. The attempt at a solution

Is this simply ln(100/13)= 2.04

or ln(13/100)= -2.04?
 

Redbelly98

Staff Emeritus
Science Advisor
Homework Helper
12,036
123
It will be a positive number (use 100/13, not 13/100). However, you still need to account for the fact that it takes 100 cycles to reach 13%.
 

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top