JEE Mains · Physics · STD 11 - 14. waves and sound
When a car is approaching the observer, the frequency of horn is \(100 Hz\). After passing the observer, it is \(50\,Hz\). If the observer moves with the car, the frequency will be \(\frac{ x }{3} Hz\) where \(x =.....\)
- A \(202\)
- B \(2000\)
- C \(20\)
- D \(200\)
Answer & Solution
Correct Answer
(D) \(200\)
Step-by-step Solution
Detailed explanation
\(f_{1}=100=f_{0}\left(\frac{C}{C-V_{5}}\right)\) \(C =\) speed of sound \(V_{S}=\) speed of source \(f_{2}=50=f_{0}\left(\frac{C}{C+V_{5}}\right)\) \(\frac{f_{1}}{f_{2}}=2=\frac{C+V_{5}}{C-V_{5}}\) \(2 C -2 V _{ s }= C + V _{ s }\) \(3 V _{ s }= C\) \(V _{ S }=\frac{ C }{3}\)…
See the Complete Solution
Get step-by-step explanations for this and 2.5 Lakh+ more JEE, NEET & CET questions.
- Unlock all solutions
- Practice the full chapter
- Track accuracy across PYQs
4.8 rated on Google Play · 14,000+ reviews
More questions from Physics
- A uniform solid cylindrical roller of mass \('m'\) is being pulled on a horizontal surface with force \(F\) parallel to the surface and applied at its centre. If the acceleration of the cylinder is \('a'\) and it is rolling without slipping then the value of \('F'\) isJEE Mains 2015 Hard
- A block of mass \(100 \mathrm{~kg}\) slides over a distance of \(10 \mathrm{~m}\) on a horizontal surface. If the co-efficient of friction between the surfaces is \(0.4\) , then the work done against friction (in \(\mathrm{J}\) ) is :JEE Mains 2024 Hard
- A body projected vertically upwards with a certain speed from the top of a tower reaches the ground in \(t_1\). If it is projected vertically downwards from the same point with the same speed, it reaches the ground in \(t_2\). Time required to reach the ground, if it is dropped from the top of the tower, is _______.JEE Mains 2024 Hard
- In the given circuit the \({AC}\) source has \(\omega=100\, {rad} {s}^{-1}\). Considering the inductor and capacitor to be ideal, what will be the current \(I\) flowing through the circuit? (in \(A\))
JEE Mains 2021 Hard - 12 wires each having resistance \(2 \Omega\) are joined to form a cube. A battery of \(6 \mathrm{~V}\) emf is joined across point \(\mathrm{a}\) and \(\mathrm{c}\). The voltage difference between \(e\) and \(f\) is ______V.
JEE Mains 2024 Hard - Consider following statements:
A. Surface tension arises due to extra energy of the molecules at the interior as compared to the molecules at the surface, of a liquid.
B. As the temperature of liquid rises, the coefficient of viscosity increases.
C. As the temperature of gas increases, the coefficient of viscosity increases
D. The onset of turbulence is determined by Reynold's number.
E. In a steady flow two stream lines never intersect.
Choose the correct answer from the options given below:JEE Mains 2025 Medium
More PYQs from JEE Mains
- Let \([ t ]\) denotes the greatest integer \(\leq t\). Then \(\frac{2}{\pi} \int \limits_{\pi / 6}^{5 \pi / 6}(8[\operatorname{cosec} x]-5[\cot x]) d x\) is equal toJEE Mains 2023 Hard
- An ordinary dice is rolled for a certain number of times. If the probability of getting an odd number \(2\) times is equal to the probability of getting an even number \(3\) times, then the probability of getting an odd number for odd number of times isJEE Mains 2021 Hard
- A bicycle tyre is filled with air having pressure of \(270\,kPa\) at \(27^{\circ}\,C\). The approximate pressure of the air in the tyre when the temperature increases to \(36^{\circ}\,C\) is \(............kPa\)JEE Mains 2023 Easy
- A body of mass 4 kg is placed on a plane at a point P having coordinate \((3,4) \mathrm{m}\). Under the action of force \(\overrightarrow{\mathrm{F}}=(2 \hat{i}+3 \hat{j}) \mathrm{N}\), it moves to a new point Q having coordinates \((6,10) \mathrm{m}\) in 4 sec . The average power and instanteous power at the end of 4 sec are in the ratio of :JEE Mains 2025 Easy
- Two satellites \(A\) and \(B\) of masses \(200\, kg\) and \(400\, kg\) are revolving round the earth at height of \(600\, km\) and \(1600\, km\) respectively. If \(T _{ A }\) and \(T _{ B }\) are the time periods of \(A\) and \(B\) respectively then the value of \(T _{ B }- T _{ A }\) [Given : radius of earth \(=6400\, km\), mass of earth \(=6 \times 10^{24}\, kg\) ]
JEE Mains 2021 Hard - Let \(\vec a = \hat i + \hat j + \hat k,\,\,\,\vec c = \hat j - \hat k\) and a vector \(\vec b\) be such that \(\vec a \times \vec b = \,\vec c\) and \(\vec a\, \cdot \,\vec b = \,3.\) Then \(\left| {\vec b} \right|\) equals?JEE Mains 2018 Hard