Equation of SHM - NEET Physics Questions
Question 21: difficult

The x-t graph of a particle undergoing simple harmonic motion is shown below. The acceleration of the particle at t = 4/3 s is :

1. √3/32π² cm/s²
2. -π/32 cm/s²
3. π²/32 cm/s²
4. -√3/32π² cm/s²
View Answer

\[ x= A sin\left( \omega t \right) \]

x= (1cm) sin (2π/8t)= (1 cm ) sin ( π/4t)

v=dx/dt= π/4 cos( π/4t)

a= dv/dt = -(π/4)²sin (π/4t)

a= -(π/4)²sin (π/4×4/3)=  -√3/32π² cm/s²

Question 22: easy

For a particle executing simple harmonic motion, the amplitude is \(A\) and time period is \(T\). The maximum speed will be:

1. \(4AT\)
2. \(\frac{2A}{T}\)
3. \(2\pi\sqrt{\frac{A}{T}}\)
4. \(\frac{2\pi A}{T}\)
View Answer

The maximum speed of a particle in simple harmonic motion is given by \(v_{\text{max}} = A\omega\). Since \(\omega = \frac{2\pi}{T}\), we get \(v_{\text{max}} = \frac{2\pi A}{T}\).

Question 23: easy

A particle is performing SHM along x-axis such that its velocity and displacement are related as \(27v^2 = 10 – 3x^2\), then time period of oscillation of particle is:

1. \(2\pi\text{ s}\)
2. \(3\pi\text{ s}\)
3. \(6\pi\text{ s}\)
4. \(9\pi\text{ s}\)
View Answer

The given equation can be rewritten as \(v^2 = \frac{10}{27} - \frac{1}{9}x^2\). Comparing this with the standard SHM equation \(v^2 = \omega^2(A^2 - x^2)\), we get \(\omega^2 = \frac{1}{9}\) which gives \(omega = \frac{1}{3}\text{ rad/s}\). Thus, the time period is \(T = \frac{2\pi}{\omega} = 6\pi\text{ s}\).

Question 24: easy

A particle is executing SHM. Then, the graph of velocity as a function of displacement is a/an:

1. straight line
2. circle
3. ellipse
4. hyperbola
View Answer

For a particle in SHM, velocity \(v = \omega \sqrt{A^2 - x^2}\). Squaring and rearranging gives \(\frac{v^2}{\omega^2 A^2} + \frac{x^2}{A^2} = 1\), which represents an ellipse.

Question 25: easy

A particle is performing simple harmonic motion of amplitude A and time period 12 seconds. If at t = 0 particle is at mean position, then distance travelled by particle in first 5 seconds will be:

1. \(\frac{7A}{3}\)
2. \(\frac{4A}{3}\)
3. \(\frac{3A}{2}\)
4. \(\frac{5A}{2}\)
View Answer

The equation of motion is \(x = A \sin\left(\frac{\pi t}{6}\right)\). At \(t = 3\text{ s}\), \(x = A\). At \(t = 5\text{ s}\), \(x = A \sin(5\pi/6) = 0.5A\). Total distance is \(A\) (from 0 to \(A\)) plus \(0.5A\) (returning from \(A\) to \(0.5A\)), which is \(1.5A = \frac{3A}{2}\).

Question 26: moderate

A simple pendulum oscillates in a vertical plane. When it passes through the mean position, the tension in the string is \(3\) times the weight of the pendulum bob. What is the maximum angular displacement of the pendulum of the string with respect to the vertical ?

1. \(30^\circ\)
2. \(45^\circ\)
3. \(60^\circ\)
4. \(90^\circ\)
View Answer

At the mean position, tension is \(T = mg + \frac{mv^2}{L}\). Given \(T = 3mg ⇒ \frac{mv^2}{L} = 2mg ⇒ v^2 = 2gL\). Using conservation of energy, \(mgL(1 - \cos\theta) = \frac{1}{2}mv^2 = mgL ⇒\cos\theta = 0 ⇒ \theta = 90^\circ\).

Question 27: easy

A particle executes SHM according to equation \(2\frac{d^2x}{dt^2} + 100x = 0\) (where \(x\) is in m and \(t\) is in second). Its time period of oscillation is

1. \(\frac{5\pi}{\sqrt{2}}\text{ s}\)
2. \(5\sqrt{2}\pi\text{ s}\)
3. \(2\sqrt{5}\pi\text{ s}\)
4. \(\frac{\sqrt{2}}{5}\pi\text{ s}\)
View Answer

Divide the given equation by 2 to get \(\frac{d^2x}{dt^2} + 50x = 0\). Comparing this with the standard SHM differential equation \(\frac{d^2x}{dt^2} + \omega^2x = 0\) gives \(\omega = \sqrt{50} = 5\sqrt{2}\text{ rad/s}\). The time period is \(T = \frac{2\pi}{\omega} = \frac{2\pi}{5\sqrt{2}} = \frac{\sqrt{2}}{5}\pi\text{ s}\).

Question 28: easy

A body oscillates in SHM according to the equation \( x = 10 cos \left(2\pi t + \frac{\pi}{4} \right)\text{ cm}\). Its instantaneous displacement at \(t = 1\text{ s}\) is

1. 10 cm
2. \(\frac{5}{\sqrt{2}}\text{ cm}\)
3. \[5\sqrt{2}\text{ cm}\]
4. \[10\sqrt{2}\text{ cm}\]
View Answer

Substituting \(t = 1\text{ s}\) in the given equation: \[x = 10 cos\left(2\pi(1) + \frac{\pi}{4}\right) = 10 cos\left(\frac{\pi}{4}
/right) = \frac{10}{\sqrt{2}} = 5\sqrt{2}\text{ cm}\].

Question 29: easy

Which of the following examples does not represent SHM?

1. Oscillations of a spring block system
2. Motion of ball bearing inside smooth curved bowl, when released slightly away from equilibrium position
3. Motion of oscillating mercury column in vertical U-tube
4. Rotation of earth about its own axis
View Answer

Rotation of the Earth about its axis is a periodic motion but not oscillatory. Since it has no restoring force or back-and-forth motion about a mean position, it is not simple harmonic motion.

Question 30: easy

The distance covered by a particle undergoing SHM in one time period is (A = amplitude of oscillation)

1. A
2. 2A
3. 4A
4. \(\frac{A}{2}\)
View Answer

In one complete time period, the particle travels from mean position to one extreme, back to mean, to the other extreme, and back to mean. Total distance is \(A + A + A + A = 4A\).