A SONAR system fixed in a submarine operates at a frequency 40.0 … - Vidyadip

Question

A SONAR system fixed in a submarine operates at a frequency $40.0 kHz$ . An enemy submarine moves towards the $SONAR$ with a speed of $360 km h ^{-1}$. What is the frequency of sound reflected by the submarine? Take the speed of sound in water to be $1450 m s ^{-1}$.

✓

Answer

The frequency of SONAR received by enemy submarine will be further reflected back to SONAR which it will receive again with a different frequency.
$SONAR$ frequency $(V_s) = 40kHz = 40 \times 10^3Hz$
Speed of enemy submarine($V_o$) = 360km/h
$=360\times\frac{5}{18}=100\text{m/s}$
Speed of sound in water = 1450m/s
Apparent frequency received by submarine is
$\text{f}'=\Big\{\frac{\text{V}+\text{V}_\text{o}}{\text{V}}\Big\}\text{f}=\Big\{\frac{1450+100}{1450}\Big\}\times40=42.76\text{kHz}$
Now, the reflected wave have a different frequency,
$\text{f}"=\Big\{\frac{\text{V}}{\text{V}-\text{V}_\text{o}}\Big\}\text{f}'=\Big\{\frac{1450}{1450-100}\Big\}\times42.76=45.93\text{kHz}$

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

More "3 Marks Question" from Waves→Waves — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Figure shows a smooth track, a part of which is a circle of radius R. A block of mass m is pushed against a spring of spring constant k fixed at the left end and is then released. Find the initial compression of the spring so that the block presses the track with a force mg when it reaches the point P, where the radius of the track is horizontal.

When you hold a pen and write on your notebook, what kind of force is exerted by you on the pen? By the pen on the notebook? By you on the notebook?

If the separation between the slits in a Young's double slit experiment is increased, what happens to the fringe-width? If the separation is increased too much, will the fringe pattern remain detectable?

A person standing on the top of a cliff $171ft$ high has to throw a packet to his friend standing on the ground $228ft$ horizontally away. If he throws the packet directly aiming at the friend with a speed of $15.0ft/s$, how short will the packet fall?

State the laws of limiting friction. Hence define coefficient of friction.

A stone tied to the end of a string 80cm long is whirled in a horizontal circle with a constant speed. If the stone makes 14 revolutions in 25s, what is the magnitude and direction of acceleration of the stone?

A circular loop of radius a, carrying a current i, is placed in a two-dimensional magnetic field. The centre of the loop coincides with the centre of the field The strength of the magnetic field at the periphery of the loop is B. Find the magnetic force on the wire.

The focal lengths of a convex lens for red, yellow and violet rays are 100cm, 98cm and 96cm respectively. Find the dispersive power of the material of the lens.

A refrigerator is to maintain eatables kept inside at $9°C$. If room temperature is $36°C$, calculate the coefficient of performance.

Prove that gravitational potential difference is the work done in carrying a unit mass from one point to another.