A ship searching for a sunken ship sent a sonar signal and detected an echo after 5 s. Class 9

A ship searching for a sunken ship sent a sonar signal and detected an echo after 5 s. Class 9

Question 1.

A ship searching for a sunken ship sent a sonar signal and detected an echo after 5 s. If ultrasonic wave travels at 1525 m s^-1 in seawater, approximately how far down in the ocean is the wreckage of the sunken ship located? Class 9

Answer:

Total time = 5 s; time to reach the sunken ship = 5/2 = 2.5 s

Distance = speed × time = 1525 × 2.5 = 3812.5 m ≈ 3812.5 m (approximately 3.8 km)

Question 2.

A vehicle is fitted with an ultrasonic distance sensor as part of parking assistance system which provides echolocation, while the driver is reversing the vehicle. It emits ultrasonic wave (about 40 kHz) which is reflected by the obstacle. When the warning beep starts sounding at a distance of 1.2 m from the obstacle, how much time is taken by ultrasonic wave to travel to the obstacle and come back? Assume the speed of ultrasonic wave in air to be 345 m s^-1. Class 9

Answer:

Total distance to travel (to obstacle and back) = 2 × 1.2 = 2.4 m

Time = distance / speed = 2.4 / 345 ≈ 0.00696 s ≈ 6.96 × 10^-3 s