Tag: sound: production of sound

Quizzes (4) Questions (118)

Questions Related to sound: production of sound

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

Which of  the  following regarding oscillatory motion is true?

  1. Motion of the earth is periodic but not oscillatory because it is not to and fro.

  2. Quivering of the string of the musical instrument is an example of oscillatory motion

  3. Motion of the earth is periodic and oscillatory motion because it is not to and fro.

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Oscillator motion is to and fro motion about a mean position. Earth motion is not a to and fro motion here, hence it is not an oscillatory motion. But as earth motion is repeated in a regular interval of time, its motion is periodic.

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

Which of the following is an example of oscillatory motion? 

  1. Heart beat of a persion

  2. Motion of earth around the sun

  3. Motion of Hally's comet around the sun

  4. Oscillations of a simple pendulam
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Oscillation of a simple pendulum is a simple harmonic motion.

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

The displacement of a particle is represented by the equation $y=sin^3(\omega t)$. The motion is 

  1. non-periodic

  2. periodic but not simple harmonic

  3. simple harmonic with period $\dfrac{2 \pi}{\omega}$

  4. simple harmonic with period $\dfrac{\pi}{\omega}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given the equation of displacement of the particle, $y={ sin }^{ 3 }\omega t$

We know $sin3\theta =3sin\theta -4{ sin }^{ 3 }\theta $
Hence, $y=\frac { (3sin\omega t-4sin3\omega t) }{ 4 } \ \Rightarrow 4\frac { dy }{ dt } =3\omega cos\omega t-4\times [3\omega cos3\omega t]\ \Rightarrow 4\times \frac { { d }^{ 2 }y }{ { dt }^{ 2 } } =-3{ \omega  }^{ 2 }sin\omega t+12\omega sin3\omega t\ \Rightarrow \frac { { d }^{ 2 }y }{ { dt }^{ 2 } } =\frac { -3{ \omega  }^{ 2 }sin\omega t+12\omega sin3\omega t }{ 4 } \ \Rightarrow \frac { { d }^{ 2 }y }{ { dt }^{ 2 } } $ is not proportional to y. 
Hence, the motion is not SHM. 
As the expression is involving sine function, hence it will be periodic. 
Also ${ sin }^{ 3 }\omega t={ \left( sin\omega t \right)  }^{ 3 }\ ={ [sin(\omega t+2\pi )] }^{ 3 }\ ={ [sin(\omega t+2\pi /\omega )] }^{ 3 }$
Hence, $y={ sin }^{ 3 }\omega t$ represents a periodic motion with period $2\pi /\omega $.

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

A horizontal plank has a rectangular block placed on it. The plank starts oscillating vertically and simple harmonically with an amplitude of 40 cm. The block just loses contact with the plank when the later is momentarily at rest. Then

  1. the period of oscillation is $2\pi /5\ s$

  2. the block weighs double its weight when the plank is at one of the positions of momentary at rest

  3. the block weighs 1.5 times its weight on the plank half way down

  4. the block weighs its true weight on the plank, when the latter moves fast
Reveal answer Fill a bubble to check yourself
B Correct answer
Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

In an electronic watch, the component corresponding to the pendulum of a pendulum clock is a__?

  1. Diode

  2. Transistor

  3. Crystal oscillator

  4. Balance wheel
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Electronic watches use a quartz crystal oscillator to provide a stable frequency for timekeeping, replacing the mechanical pendulum or balance wheel.

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

An oscillator is producing FM waves of frequency 2kHz with avariation of 10kHz. The modulating index=?

  1. 0.20

  2. 5.0

  3. 0.67

  4. 1.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Modulation Index , $m _f=\dfrac{\text{Maximum frequency deviation}}{\text{Modulating frequency}}$

$\Rightarrow m _f= \dfrac{10 kHz}{2 kHz}$
$\Rightarrow m _f=5$

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

Which one of the following will take place when a watch based on oscillating spring is taken to a deep mine?

  1. It will indicate the same time  on earth

  2. It will become fast

  3. It will become slow

  4. It will stop working
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A watch based on an oscillating spring (like a balance wheel watch) has a period T = 2*pi*sqrt(m/k). This period depends only on the mass and the spring constant, neither of which changes with gravity or depth. Thus, it keeps the same time.

Multiple choice physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

A simple harmonic oscillator of angular frequency 2 rad $s^{-1}$ is acted upon by an external force $F= sin tN.$ If the oscillator is at rest in its equilibrium position at t=0, its position at later times is proportional to 

  1. $ sin t+ \frac{1}{2}cos 2t$

  2. $ cos t -\frac{1}{2}sin2t$

  3. $sint -\frac{1}{2}sin2t$

  4. $sin t +\frac{1}{2}sin 2t$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The solution contains term proportional to $sin t$, $sin 2t$ & the only option consistent with initial conditions is (C)