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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Simple Harmonic Motion

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Simple Harmonic Motion

At a specific instant, the magnitudes of the position, velocity,...

At a specific instant, the magnitudes of the position, velocity, and acceleration of a particle undergoing simple harmonic motion are observed to be 2 cm2 \text{ cm}, 1 m/s1 \text{ m/s}, and 10 m/s210 \text{ m/s}^2, respectively. Determine the amplitude and the time period of the motion.

Options

  1. A4.9 cm4.9 \text{ cm}, 0.28 s0.28 \text{ s}
  2. B4.9 cm4.9 \text{ cm}, 0.56 s0.56 \text{ s}
  3. C6.4 cm6.4 \text{ cm}, 0.28 s0.28 \text{ s}
  4. D2.4 cm2.4 \text{ cm}, 0.14 s0.14 \text{ s}

Correct answer

A. 4.9 cm4.9 \text{ cm}, 0.28 s0.28 \text{ s}

Step-by-step solution

Given x=2 cm=0.02 mx = 2 \text{ cm} = 0.02 \text{ m}, v=1 m/sv = 1 \text{ m/s}, and a=10 m/s2a = 10 \text{ m/s}^2.

In simple harmonic motion, the magnitude of acceleration is given by a=ω2xa = \omega^2 x.

Substituting the given values:

10=ω2×0.0210 = \omega^2 \times 0.02

ω2=100.02=500 rad2/s2\omega^2 = \dfrac{10}{0.02} = 500 \text{ rad}^2/\text{s}^2

ω=500=105 rad/s\omega = \sqrt{500} = 10\sqrt{5} \text{ rad/s}

The time period TT is given by:

T=2πω=2π105≈2×3.1422.36≈0.28 sT = \dfrac{2\pi}{\omega} = \dfrac{2\pi}{10\sqrt{5}} \approx \dfrac{2 \times 3.14}{22.36} \approx 0.28 \text{ s}

The velocity in SHM is given by v=ωA2−x2v = \omega \sqrt{A^2 - x^2}.

Squaring both sides:

v2=ω2(A2−x2)v^2 = \omega^2 (A^2 - x^2)

Substituting the known values:

12=500(A2−0.022)1^2 = 500 (A^2 - 0.02^2)

1=500(A2−0.0004)1 = 500 (A^2 - 0.0004)

A2−0.0004=1500=0.002A^2 - 0.0004 = \dfrac{1}{500} = 0.002

A2=0.002+0.0004=0.0024 m2A^2 = 0.002 + 0.0004 = 0.0024 \text{ m}^2

A=0.0024 m=24×10−2 m=24 cmA = \sqrt{0.0024} \text{ m} = \sqrt{24} \times 10^{-2} \text{ m} = \sqrt{24} \text{ cm}

Since 24≈4.899\sqrt{24} \approx 4.899, the amplitude is A≈4.9 cmA \approx 4.9 \text{ cm}.
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