Question

The amplitude of a damped oscillator decreases to $0.9$ times its original magnitude is $5\, s$. In another $10\, s$ it will decrease to a times its original magnitude, where $\alpha$ equals

• A. 0.7
• B. 0.81
• C. 0.729
• D. 0.6

Answer 1

Answer: (C)

0.729

Answer 2

Amplitude decreases exponentially. In 5 s it remains 0.9 times. Therefore in total 15 s it will remains (0.9) (0.9) Answer is 4. (0.9) = 0.729 times its original value.