A standard sheet of laser-printer paper of the usual thickness, either US "letter" size or international "A4" size, weighs 4.5 grams. That means 100 sheets weighs almost exactly one pound.
Answer:
True: For a sound wave to propagate, air particles must be displaced in the direction of propagation - it is the displacement of these particles that causes the eardrum to vibrate and recognize the sound.
Yea it would be barrier. since the stream has a cover for the water
