Mechanical Ways to Detect Objects and Explore Internal Structures

The video tutorial covers the nature of sound waves, their detection by the human ear, and the range of human hearing. It explains ultrasound waves, their higher frequencies, and their applications in medical and industrial imaging. The tutorial also discusses seismic waves, their types, and how they provide insights into the Earth's core structure. Finally, it covers echo sounding, a technique using high-frequency sound waves to measure water depth and detect underwater objects.

What is the frequency range of normal human hearing?

• 10 Hz to 10,000 Hz

• 30 Hz to 30,000 Hz

• 20 Hz to 20,000 Hz

• 40 Hz to 40,000 Hz

Why can't humans hear ultrasound waves?

• They are too loud

• They have frequencies below 20 Hz

• They have frequencies above 20 kHz

• They are too soft

How are ultrasound waves used in medical imaging?

• By reflecting off bones

• By creating vibrations in tissues

• By passing through the skin

• By reflecting at boundaries between different media

What type of seismic wave can travel through both liquids and solids?

• P waves

• S waves

• Rayleigh waves

• Surface waves

In echo sounding, what is the depth of the fish if the time taken for the echo to return is 0.52 seconds and the speed of sound in water is 1500 m/s?

• 390 meters

• 780 meters

• 520 meters

• 150 meters