A whistle revolves in a circle with an angular speed of 20 ; rad/… - Vidyadip

MCQ

A whistle revolves in a circle with an angular speed of $20\; rad/sec$ 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 in the same plane ... $Hz$ ? ($v = 340 \;m/s$)

A
$333$
✓
$374$
C
$385$
D
$394$

✓

Answer

Correct option: B.

$374$

b
(b) Minimum frequency will be heard, when whistle moves away from the listener.

${n_{\min }} = n\,\left( {\frac{v}{{v + {v_s}}}} \right)$ where $v = r\omega = 0.5 \times 10 = 1\,m/s$

==> ${n_{\min }} = 385\,\left( {\frac{{340}}{{340 + 10}}} \right) = 374Hz.$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

JEE STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Which of the following is deflected by electric field

If the radius of earth is reduced to three-fourth of its present value without change in its mass then value of duration of the day of earth will be__________.hours $30$ minutes.

Current in a circuit falls from $5.0\, A$ to $0.0\, A$ in $0.1\, s$. If an average $emf$ of $200\, V$ induced, give an estimate of the self-inductance of the circuit....$H$

Two waves are propagating to the point $P$ along a straight line produced by two sources $A$ and $B$ of simple harmonic and of equal frequency. The amplitude of every wave at $P$ is $‘a’$ and the phase of $A$ is ahead by $\frac{\pi }{3}$ than that of $B$ and the distance $AP$ is greater than $BP$ by $50 cm.$ Then the resultant amplitude at the point $P$ will be, if the wavelength is $1$ meter

A sound source $S$ is moving along a straight track with speed $v,$ and is emitting sound of frequency $v_{o}$ (see figure). An observer is standing at a finite clistance, at the point $O$, from the track. The time variation of frequency heard by the observer is best represented by

$\left(t_{0}\right.$ represents the instant when the distance between the source and observer is minimum)

An inductor $(L = 100\, mH),$ a resistor $(R = 100 \, \Omega )$ and a battery $(E = 100 \,V)$ are initially connected in series as shown in the figure. After a long time the battery is disconnected after short circuiting the points $A$ and $B.$ The current in the circuit $1 \,ms$ after the short circuit is-

Modulus of rigidity of a liquid

The unit of magnetic moment is

The figures represent three cases of a ray passing through a prism of angle $A.$ The case corresponding to minimum deviation is

If the time period $(T)$ of vibration of a liquid drop depends on surface tension $(S)$, radius $(r)$ of the drop and density $(\rho )$ of the liquid, then the expression of $T$ is