To locate objects in their environments, bats in flight and porpoises under water both use ultrasound waves with frequencies that are beyond human hearing. These animals produce an ultrasonic wave and then detect echoes from nearby objects.If a porpoise and a bat both produce ultrasonic waves when they are 16 m from an object, which animal would hear its echo first and why?

Question

Answer: B - The porpoise would hear its echo first because sound travels faster in water than in air.

Ted Chan · Accepted Answer

The porpoise would hear its echo first because sound travels faster in water than in air.

AP Physics B Practice Exam