11. How do you call the waves in which the particles move back and forth parallel to the direction of the
motion of the wave?

a.longitudinal wave

b. Transverse

c. Electromagnetic

d. Mechanical

15. Why do you think a blind man can walk alone with a long stick in his hand?

a. He uses his stick to guide his walik.

b. He uses his stick to feel what is happening around him.

c.He uses his stick for formality.

d. He makes use of the reflected sound produced by the stick to guide his direction​