MHT CET · Physics · Waves and Sound
A car sounding a horn of frequency \(1000 \mathrm{~Hz}\) passes an observer. The ratio of frequencies of the both noted by the observer before and after passing of the car is 11:9. If the speed of sound is \(V\), the speed of the car is
- A V
- B \(\frac{V}{10}\)
- C \(\frac{V}{100}\)
- D \(\frac{V}{5}\)
Answer & Solution
Correct Answer
(B) \(\frac{V}{10}\)
Step-by-step Solution
Detailed explanation
\(n_{\text {Before }}=\left(\frac{v}{v+v_c}\right) n\)
And \(n_{\text {After }}=\left(\frac{v}{v+v_c}\right) \cdot n\)
\(\frac{n_{\text {Before }}}{n_{\text {After }}}=\frac{11}{9}=\left(\frac{v+v_c}{v-v_c}\right)\)
\(\Rightarrow v_c \Rightarrow \frac{v}{10}\)
And \(n_{\text {After }}=\left(\frac{v}{v+v_c}\right) \cdot n\)
\(\frac{n_{\text {Before }}}{n_{\text {After }}}=\frac{11}{9}=\left(\frac{v+v_c}{v-v_c}\right)\)
\(\Rightarrow v_c \Rightarrow \frac{v}{10}\)
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
- The deflection in a moving coil galvanometer is reduced to half when it is shunted with ' \(X^{\prime} \Omega\) coil. The relation between ' \(\mathrm{X}^{\prime}\) and resistance of galvanometer ' \(\mathrm{G}^{\prime}\) isMHT CET 2020 Easy
- A piece of semiconductor is connected in series in an electric circuit. On increasing the temperature, the current in the circuit willMHT CET 2025 Easy
- Four particles each of mass M are placed at the corners of a square of side L . The radius of gyration of the system about an axis perpendicular to the square and passing through its centre isMHT CET 2025 Medium
- Magnetic susceptibility of a paramagnetic substance isMHT CET 2019 Easy
- Two cars start from a point at the same time in a straight line and their positions are represented by \(\mathrm{x}_1(\mathrm{t})=\mathrm{at}+\mathrm{bt}^2\) and \(\mathrm{x}_2(\mathrm{t})=\mathrm{Ft}-\mathrm{t}^2\). At what time do the cars have the same velocity?MHT CET 2024 Medium
- To determine the internal resistance of a cell by using a potentiometer, the null point is at \(1 \mathrm{~m}\) when the cell is shunted by \(3 \Omega\) resistance and at a length \(1.5 \mathrm{~m}\) when cell is shunted by \(6 \Omega\) resistance. The internal resistance of the cell is.MHT CET 2022 Medium
More PYQs from MHT CET
- Acetyl group of acetyl CoA contains how many carbon atoms?MHT CET 2022 Hard
- Two spherical black bodies have radii ' \(R_1\) ' and ' \(R_2\) '. Their surface temperatures are \(T_1 K\) and \(T_2 K\) respectively. If they radiate the same power, the ratio \(\frac{\mathrm{R}_1}{\mathrm{R}_2}\) isMHT CET 2025 Easy
- If \(6 \mathrm{~g}\) of solute dissolved in \(100 \mathrm{~g}\) of water lowers the freezing point by \(0.93 \mathrm{~K}\). What is molar mass of solute?
\(
\left(\mathrm{K}_{\mathrm{f}}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)
\)MHT CET 2021 Medium - The angle between the lines \(y^{2} \sin ^{2} \theta-x y \sin ^{2} \theta+x^{2}\left(\cos ^{2} \theta-1\right)=0\) isMHT CET 2020 Medium
- For the following combination of logic gates, when all the three inputs \(A\), \(B\) and \(C\) are first 'high' and then 'low', the output \(Y\) will be respectively.
MHT CET 2022 Easy - ln nature, flowers and their pollinator species are tightly linked with one another. This example involves _________.MHT CET 2024 Easy