Gravity only determines the path in projectile motion
When you're in an airplane that's 7 miles up off the ground, the strength of gravity plunges to only 99.6 percent of its strength all the way down on the ground.
A big heavy person, who weighs 200 pounds down at the airport, weighs only 199 pounds 4.7 ounces in a plane at the altitude of 7 miles.
Sound needs medium to travel and it can not travel without medium
so sound wave is a travelling wave
now we also know that sound wave propagate in form of rarefaction and compression.
So all medium particles travel in the direction of wave only
so it is a longitudinal wave also
so correct answer will be
<em>mechanical longitudinal </em>
