A goods train blows its whistle on a straight track 4km away from two boys. Boy A has his ear placed on one of the steel rails, while Boy B stands nearby in the open air.
(i) Calculate the time taken for the sound of the whistle to reach Boy A through the rail, if the speed of sound in steel is 5800m/s.
(ii) Calculate the time taken for the same sound to reach Boy B through the air, if the speed of sound in air is 340m/s.
(iii) How much earlier (in seconds) will Boy A hear the whistle compared with Boy B?
(iv) If the rail were made of aluminium, for which the speed of sound is about 6400m/s, determine the new time difference between the arrivals of the sound for the two boys.