Tag: oscillation - amplitude, time period and frequency of oscillation

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Questions Related to oscillation - amplitude, time period and frequency of oscillation

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

Two trains A and B are approaching each other with $108 km {h}^{-1}$ and $126 kg {h}^{-1}$ respectively. If the train 'A' sounds a whistle of frequency 500 Hz, find the frequency of the whistle as heard by a passenger in the train 'B'.

(a) before the trains cross each other and

(b) after the trains cross each other. (Take velocity of sound as $330 {ms}^{-1}$)

  1. 608 Hz, 410 Hz

  2. 410 Hz, 608 Hz

  3. 330 Hz, 550 Hz

  4. 310 Hz, 660 Hz
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Convert speeds to m/s: 108 km/h = 30 m/s, 126 km/h = 35 m/s. Before crossing, f' = f * ((v + vo) / (v - vs)) = 500 * ((330 + 35) / (330 - 30)) = 500 * (365 / 300) = 608.3 Hz. After crossing, f' = f * ((v - vo) / (v + vs)) = 500 * ((330 - 35) / (330 + 30)) = 500 * (295 / 360) = 409.7 Hz.

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 open pipe pressure at the ends of the pipe is

  1. minimum

  2. maximum

  3. zero

  4. depending on temperature, it can be maximum or minimum.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In an open pipe, the ends are pressure nodes (displacement antinodes) because they are open to the atmosphere, meaning the pressure variation is zero relative to atmospheric pressure.

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

If a vibrator strikes the water $50$ times in $5s$, then the frequency of wave is

  1. $10 Hz$

  2. $0.5 Hz$

  3. $5 Hz$

  4. $0.1 Hz$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Total number of vibrations, in $5s$ is $50$.
So, number of vibrations in $1s$ is $\dfrac{50}{5}=10$
Frequency$=10Hz$
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

One sound wave strikes a person's ear every $1/100$ of a second. The speed of sound where the person is located is $345 m/s$.
What is the frequency of the sound?

  1. $3.45\ Hz$

  2. $34,500\ Hz$

  3. $0.01\ Hz$

  4. $100\ Hz$

  5. $2.9\ Hz$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Time period of sound wave       $T = \dfrac{1}{100}$ second


$\therefore$ Frequency of sound wave      $\nu = \dfrac{1}{T} =100$  $Hz$

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

If you go on increasing the stretching force on a wire in a guitar, its frequency

  1. Increases

  2. Decreases

  3. Remains unchanged

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

When a stretching force is applied to a string or a wire, it applies a restoring force in the opposite direction. This force tends to bring the wire in its original length. It is known as tension in wire.

When we apply a stretching force on the wire of a guitar, the wire applies tension backwards. Greater the stretching force, greater is the tension.
The frequency of vibration of a stretched wire is directly proportional to the square root of the tension in it.
Hence on increasing the stretching force on a wire in a guitar, its frequency increases

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 sounds having frequency of $20$ Hz to $20,000$ Hz are

  1. Ultrasound

  2. Infrasonics

  3. Hypersonics

  4. Audible Sounds
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the case of sound waves, having frequency in between $20$ Hz and $20,000$ Hz, called audible sound and  waves of frequency smaller than $20$ Hz are called infrasonic and waves having frequency greater then $20,000$ Hz, called Hypersonics sounds.

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 time taken by a particle in reaching from a trough to its next crest in a transverse wave is

  1. T/4

  2. T/2

  3. T

  4. 3T/4
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A crest and a trough are separated by a distance of $\lambda/2$. A distance of $\lambda/2$ corresponds to a time difference of T/2

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 equation of motion of a particle is $x = a cos(\alpha t)^2$. The motion is

  1. periodic but not oscillatory

  2. periodic and oscillatory

  3. oscillatory but not periodic

  4. neither periodic nor oscillatory.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The motion is oscillatory but not periodic because the oscillations are followed from the maximum displacement (negative extreme) at t=0, the corresponding echo is equal to π/2