The human range of hearing is between 20 and 20,000 Hz. What is the corresponding range in wavelengths for sound in air at 25 °C?

Which type of electromagnetic waves are dangerous enough to be used to kill cancerous cells? (a)gamma rays (b)visible light (c)infrared light (d)microwaves

Abearing is designed to a reduce friction b. support a load c.guide moving parts such as wheels, shafts and pivots d. all of the above

Aballet student who learns with the of his instructor is demonstrating learning.