Something rounded. No corners, such as a sphere.
Aerodynamics.
The denser the faster. ie: it will travel faster through quartz than sandstone.
sound travel faster through soled because of tighter packed particles
Waves travel faster through denser materials. However, Electromagnetic waves travel faster through less dense materials. It travels fastest in vacuum.
Light travels much faster than sound, through wood.
Sound
Air.
15 times faster
sound travels faster through water than air.
no sound travels faster through solids.
I believe that sound travels faster through iron because it bounces off the sides, and causes it to travel faster, reaching the other side.
Sound waves travel faster through denser media, like solids, because the molecules are closer together, making it easier to pass the sound from molecule to molecule. Light and other electromagnetic waves travel faster through less dense media, and they travel fastest through a vacuum.
The denser the material the faster sound will travel. Maple syrup is denser then sand.