Q79 / 120 · JEE Main 2007 · Physics

The displacement of an object attached to a spring and executing simple harmonic motion is given by $x=2 \times 10^{-2} \cos \pi t$ metres. The time at which the maximum speed first occurs is

  • Correct answer
    A
    $0.5 \mathrm{~s}$
  • B
    $0.75 \mathrm{~s}$
  • C
    $0.125 \mathrm{~s}$
  • D
    $0.25 \mathrm{~s}$

Solution

$\begin{aligned} & \mathrm{x}=2 \times 10^{-2} \cos \pi t \\ & \mathrm{v}=-0.02 \pi \sin \pi t \end{aligned}$ $\mathrm{v}$ is maximum at $\mathrm{t}=\frac{1}{2}=0.5 \mathrm{~sec}$

Hence, the correct answer is option: 'A'.

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