Question

An Australian humpback whale emits a SONAR pulse, which returns from a predator located at a distance of x metre in 2 seconds. If the speed of sound in sea water is 1531 m/s, then the value of x is

• A. $1000m$
• B. $1531m$
• C. $3062m$
• D. $765.5m$

Answer 1

The correct option is B $1531m$



It is given that the distance between the whale and the predator is x.

Total distance covered by SONAR pulse $=x+x=2x$

Speed of sound in water, $v=1531m/s$

Total time taken by SONAR pulse to return to whale, $t=2s$

Now, $\text{speed(v)}=\frac{\text{Total distance}}{\text{Time taken}}\Rightarrow v=\frac{2x}{t}\Rightarrow x=\frac{vt}{2}=\frac{1531\times 2}{2}\Rightarrow x=1531m$

Hence, the correct answer is option (b).