Question

The angular frequency of a spring block system is $\omega_{0}$. This system is suspended from the ceiling of an elevator moving downwards with a constant speed $v _{0}$. The block is at rest relative to the elevator. Lift is suddenly stopped. Assuming the downwards as a positive direction, choose the wrong statement:

• A. The amplitude of the block is $\frac{ v _{0}}{\omega_{0}}$
• B. The initial phase of the block is $\pi$.
• C. The equation of motion for the block is $\frac{ v _{0}}{\omega_{0}} \sin \omega_{0} t$.
• D. The maximum speed of the block is $v _{0}$.

Answer 1

Answer: (B)

$V _{0}= A \omega_{0} \Rightarrow A =\frac{ v _{0}}{\omega_{0}}$
Block moving towards the direction hence $\phi=0$
$v _{\max }= v _{0}$