SPH102 CAT 1 FEB 2023 SOLVED

Use the following constants where applicable

• Speed of sound in air = 340 m/s.
• Speed of electromagnetic wave in air = 3x10⁸ m/s 

(1) Given a wave of frequency of 3 kHz, determine its wavelength if it is;

(a) a sound wave

(b) an electromagnetic wave

(2)The equation for a transverse progressive wave may be represented by A = a sin (bt-cx)

(a) State what the constants a, b and c represent.                                     

a -amplitude

b-angular velocity, ω

c-wave number, k

(b)show that

(3) A 1 m guitar string of mass 6 g is under a tension of 30 N.  If the string oscillates at a frequency of 500 Hz, find the wavelength of the waves generated.                   

Hence 

(4)A truck travelling at 10 m/s sounds its horn which has a frequency of 500 Hz. This is heard in car that is travelling behind the truck, in the same direction, at a speed of 20 m/s. The sound can also be heard in the car by reflection from a bridge ahead. Find the two frequencies of sound heard by the driver of the car. 

(i) Observer approaching, source moving away 

(ii) observer approaching, reflected sound appears similar to that of approaching source 

Dr. Margaret W. Chege