If a wave is travelling in a positive \(x\text-\)direction with \(A= 0.2~\text{m},\)  \(v=360~\text{m/s},\) and \(\lambda= 60~\text{m},\) then the correct expression for the wave will be:

1.	\({y}=0.2 \sin \left[2 \pi\left(6{t}+\frac{x}{60}\right)\right]\)
2.	\({y}=0.2 \sin \left[ \pi\left(6{t}+\frac{x}{60}\right)\right]\)
3.	\({y}=0.2 \sin \left[2 \pi\left(6{t}-\frac{x}{60}\right)\right]\)
4.	\(y=0.2 \sin \left[ \pi\left(6{t}-\frac{x}{60}\right)\right]\)

A whistle revolves in a circle with an angular speed ω = 20 rad/sec using a string of length 50 cm. If the frequency of sound from the whistle is 385 Hz, then what is the minimum frequency heard by an observer which is far away from the centre? (V_sound = 340 m/s)
1. 385 Hz
2. 374 Hz
3. 394 Hz
4. 333 Hz

An observer moves towards a stationary source of sound with a speed of 1/5th of the speed of sound. The wavelength and frequency of the source emitted are λ and f, respectively. The apparent frequency and wavelength recorded by the observer are, respectively:
1. 1.2f, 1.2λ
2. 1.2f, λ
3. f, 1.2λ
4. 0.8f, 0.8λ

A steel wire \(0.72~\text{m}\) long has a mass of \(5\times10^{-3}~\text{kg}\). If the wire is under tension of \(60~\text{N}\), the speed of transverse waves on the wire will be:
1. \(85~\text{m/s}\)
2. \(83~\text{m/s}\)
3. \(93~\text{m/s}\)
4. \(100~\text{m/s}\)

The phase difference between two waves, represented by
\(y_1= 10^{-6}\sin \left\{100t+\left(\frac{x}{50}\right) +0.5\right\}~\text{m}\)
\(y_2= 10^{-6}\cos \left\{100t+\left(\frac{x}{50}\right) \right\}~\text{m}\)
where \(x\) is expressed in metres and \(t\) is expressed in seconds, is approximate:
1. \(2.07~\text{radians}\)
2. \(0.5~\text{radians}\)
3. \(1.5~\text{radians}\)
4. \(1.07~\text{radians}\)

A car is moving towards a high cliff. The car driver sounds a horn at a frequency of 'f'. The reflected sound heard by the driver has a frequency of 2f. If 'v' is the velocity of sound, then the velocity of the car, in the same velocity units, will be:
1. v/3
2. v/4
3. v/2
4. v/$\sqrt{2}$

If a source moves perpendicularly to the listener, then the change in frequency will be:
1.  2n
2.  n
3.  n/2
4.  Zero