The behavior of a sound wave is affected by the density of the medium, the temperature of the medium and the pressure of the medium if it is a gas. Motion of the medium independent of the sound wave may also affect the way sound propagates.
Yes, you may check-in for your Delta Air Lines (DL) flight with your mobile device starting 24 hours and ending 60 minutes before the scheduled departure time (depending on your departure city and destination) to receive a mobile boarding pass on your mobile device.
Quick Answer. Passengers who fly Delta One, first class and business class on Delta Airlines can check up to two bags of 70 pounds each for free on all flights except for flights to Brazil. On these flights, they can check up to three bags of 70 pounds each for free. Continue Reading.