A motorcyclist going around a circular track of radius $50\ m$ with a speed of $25\ m/s$ , is at a point $X$. A static siren at $Y$ is emitting sound of frequency $n$. How many times (approximately) in an hour will the motor cyclist hear the sound of actual frequency $Y$ ?
Medium
Download our app for free and get started
Actual frequency willbe heard when velocity of motor cyclist is perpendicular to line joining the source and motor cyclist is perpendicular to line joining the source and motor cyclist. If will happen $2$ times per round.
No. of rounds in a hour $=\frac{3600}{4 \pi}$
(where $4 \pi$ is time for one round) $\approx 287$
Answer is double of $287$ ie $574$
Download our appand get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
Similar Questions
- 1A uniform tube of length $60.5\,cm$ is held vertically with its lower end dipped in water. A sound source of frequency $500\,Hz$ sends sound waves into the tube. When the length of tube above water is $16\,cm$ and again when it is $50\,cm,$ the tube resonates with the source of sound. Two lowest frequencies (in $Hz$), to which tube will resonate when it is taken out of water, are (approximately).View Solution
- 2One insulated conductor from a household extension cord has a mass per unit length of $μ.$ A section of this conductor is held under tension between two clamps. A subsection is located in a magnetic field of magnitude $B$ directed perpendicular to the length of the cord. When the cord carries an $AC$ current of $"i"$ at a frequency of $f,$ it vibrates in resonance in its simplest standing-wave vibration state. Determine the relationship that must be satisfied between the separation $d$ of the clamps and the tension $T$ in the cord.View Solution
- 3Which of the following functions for $y$ can never represent a travelling wave?View Solution
$(a)$ $\left(x^2-v t\right)^2$
$(b)$ $\log \left[\frac{(x+v t)}{x_0}\right]$
$(c)$ $e^{\left\{-\frac{(x+v t)}{x_0}\right\}^2}$
$(d)$ $\frac{1}{x+v t}$
- 4In a closed organ pipe the frequency of fundamental note is $50 Hz$. The note of which of the following frequencies will not be emitted by it .... $Hz$View Solution
- 5The power of sound from the speaker of a radio is $20$ milli watt by turning the knob of the volume control the power of the sound is increased to $400$ milli watt. The power increase in decibles as compared to the original power is ..... $dB$View Solution
- 6You are driving in your car listening to music on the radio. Your car is equipped with radio that can recieved radio singals of frequency $(f_1 \approx\, 3\, MHz),$ other of frequency $(f_2 \approx\, 30\, MHz),$ and third of frequency $(f_3 =\, 3\, GHz),$. You enter a tunnel with a circular opening of diameter $10\ m.$ Which kind of radio signal will you be able to receive the longest as you continue to travel in the tunnel ?View Solution
- 7A motor car blowing a horn of frequency $124\,vib/sec$ moves with a velocity $72\, km/hr$ towards a tall wall. The frequency of the reflected sound heard by the driver will be .... $vib/sec$ (velocity of sound in air is $330\, m/s$)View Solution
- 8The given diagram shows a detector placed between a transmitter of sound waves and a metal plate. At three adjacent points, $ R, S$ and $T$ , the meter shows zero intensity. Which of the following is the frequency of the emitted wave ... $Hz$ ? (Take the velocity of sound as $ = 300\ m/s$ )View Solution
- 9A 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 byView Solution
$\left(t_{0}\right.$ represents the instant when the distance between the source and observer is minimum)
- 10Four wires of identical length, diameters and of the same material are stretched on a sonometre wire. If the ratio of their tensions is $1 : 4 : 9 : 16$ then the ratio of their fundamental frequencies areView Solution