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 $\varphi =0$
$v_{\max }=v_0$