The Doppler effect: A child's toy consists of a whistle on the end of a string 1 meter long. When you whirl the whistle around in a circle on the end of the string, the movement of the air makes the whistle sound. (a) The whistle makes the note C6. What is the frequency? (b) What is the circumference of the circle the whistle travels around? (c) A child playing with the toy whirls it around their head twice per second in a horizontal circle. What is the velocity of the whistle? (d) You are standing to one side listening to the sound of the whistle. Instead of a steady note you hear a variation in pitch, the note going up and down as the whistle makes its circle. Briefly explain the physics: why does the pitch vary? (e) What are the highest and lowest frequencies the note attains? (f) Hence by how many musical cents does the pitch vary