Question

☆●In a submarine equipped with SONAR, the time interval between generation of wave and reception of its echo after reflection from the enemy submarine is found to be 40s. If the speed of ultrasonic waves in sea water is 1450m/s, then the distance of *


a)38Km

b) 48Km

c) 29Km

d) 68Km

please answer it fast ​

Answer 1

Answer :-

Distance of the submarine from enemy submarine is 29 km [Option.c]

Explanation :-

We have :-

→ Time taken by the wave (t) = 40 s

→ Speed of the wave (v) = 1450 m/s

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If 'd' is the distance of the submarine from the enemy submarine, then total distance travelled by the wave in time interval 't' is '2d' .

Speed = Distance/Time

⇒ v = 2d/t

⇒ vt = 2d

⇒ d = vt/2

Putting values in obtained formula :-

d = vt/2

⇒ d = (1450 × 40)/2

⇒ d = 1450 × 20

⇒ d = 29000 m

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Finally let's convert the obtained distance from 'm' to 'km' .

⇒ 1 m = 0.001 km

⇒ 29000 m = 29000(0.001) km

⇒ 29 km

Answer 2

QUESTION:-

In a submarine equipped with SONAR, the time interval between generation of wave and reception of its echo after reflection from the enemy submarine is found to be 40s. If the speed of ultrasonic waves in sea water is 1450m/s, then the distance of *

a)38Km

b) 48Km

c) 29Km

d) 68Km

EXPLANATION:-

Here speed= s

Time take=t

And distance=2d

We know :-

$\tt\;Speed=\frac{distance}{time}$

SIMPLIFYING IT

v = 2d/t

 vt = 2d

 d = vt/2

NOW LET'S SUBSTITUTE THE VALUES GIVEN IN THE QUESTION:-

$\longrightarrow \bf\;d=\frac{1450\times40}{2}\\\\\\longrightarrow \bf\;d=\frac{58000}{2}\\\\\\\longrightarrow \bf\;\boxed{\bf\;d=29000\;m}}$

Since the option are in km so let's convert it in Km in metre

1 m=1000 km

29000 m=29000/1000=>29 km

So the distance is 29 km

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