(a) why are sound waves called mechanical waves ? list two practical applications of reflection of these waves. (b) a stone is dropped from the top of a tower 125 m high into a pond of water at the base of the tower. when is the splash heard at the top ? (g = 10 m/s2 and speed of sound = 340 m/s)

This is a form of winter precipitation. it is frozen precipitation falling as ice pellets. snowflakes melt into raindrops as they pass through a thin layer of warmer air. the raindrops then refreeze into particles of ice when they fall into a layer of sub-freezing air near the surface of the earth. this precipitation is called a) hail. b) rain. c) sleet. d) snow.

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.

Suppose astronomers built a 140-meter telescope. how much greater would its light-collecting area be than that of the 10-meter keck telescope? express your answer using two sign