Question

A MET office employee, who is standing still, observes a storm coming towards him at 15 m/s. The thunder that he hears (the ‘observed’ frequency) is at a frequency of 140 Hz. The speed of sound is 343 m/s. i) Show that the frequency the employee hears will increase if he decides to move toward the storm at 4 m/s. ii) The employee hears a frequency of 157 Hz as he drives away from the storm. At what speed is he driving away? iii) There is a delay between the discharge of lightning in the middle of the storm and the arrival of the sound of thunder. Using physics principles, explain this delay and how one might use this information to estimate distance from the observer to the storm.

Answer 1