Wave Mechanics Question 605
Question: A pendulum with time period of 1s is losing energy. At certain time its energy is 45 J. If after completing 15 oscillations, its energy has become 15 J, its damping constant (in s~1) is :
Options:
A) $ \frac{1}{2} $
B) $ \frac{1}{30} $
C) 2
D) $ \frac{1}{15}In,3 $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] As we know, $ E=E _{0}{{e}^{-\frac{bt}{m}}} $
$ 15=45{{e}^{-\frac{b15}{m}}}\Rightarrow \frac{1}{3}={{e}^{-\frac{b15}{m}}} $ [As no. of oscillations = 15 so t = 15 sec] Taking log on both sides $ \frac{b}{m}=\frac{1}{15}ln3 $
BETA
