Question

Ordinary sound wave can't detect cracks in metal blocks. Why?

Answer 1

Answer:

The cracks or holes inside the metal blocks, which are invisible from outside reduces the strength of the structure. Ultrasonic waves are allowed to pass through the metallic block and detectors are used to detect the transmitted waves.

Answer 2

Answer:

Here's the answer ll

this is so because it reduces the strength of the object.

hope it helps you