(a) On which day would sound wave travel faster: on a hot or cold day? Explain. (b) Why are megaphones shaped like funnels? (c) A ray of light is incident on a surface of a ectangular glass prism of refractive index 1.5 illustrated in the diagram below.
(i) Copy the diagram a label the angles of: () Incidence (x); () Reflection (y); () refraction (z); with t glass letters indicated. (ii) Calculate the angle refraction to the nearest whole number. (d) A sonomesr wire vibrates in simple harmoi motion with a maximum amplitude of 1.0 cm. Calculate the frequency of vibration of the wire, giv that the magnitade of the maximum acceleration of the wire is 980ms. []
Explanation
(a) Sound wave travels faster on a hot day because the speed of sound is proportional to the square root of absolute temperature (V ), hence the higher the greater the speed of sound wave. (b) Megap:iones are shaped like a funnels because at the smaller end of the cone, the sound energy comes into contact will a small mass of air producing greater intensity. As it comes out of the larger open end, the energy sets a larger air mass into vibration, hence the final sound is louder. (c) (i)
(ii) n = sinr = = r = sin0.5774 = 35 (d) a = but a = (2r f = = 50Hz
