(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)

a high pressure system is a dense air mass that is usually cooler and drier than the surrounding air. a low pressure system is a less dense air mass that is usually wetter and warmer than the surrounding air.

in general, areas that experience high atmospheric pressure also experience fair weather. low pressure systems can cause the formation of clouds and storms. air usually flows from areas of high pressure to areas of low pressure..

a straight line sloped