Q. Ultrasonic signal sent from SONAR returns to it after reflection from a rock after a lapse of $1\ sec.$ If the velocity of ultrasound in water is $1600\ ms^{- 1},$ the depth of the rock in water is
A) $300\ m$
B) $400\ m$
C) $500\ m$
D) $800\ m$
Explanation
(d) If $d$ is the distance of rock from SONAR then
$2d = vt \Rightarrow d = \frac{v \times t}{2} = \frac{1600 \times 1}{2} = 800m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.