Sound waves are not able to travel in a vacuum, sound requires a medium such as air or a solid for example. Satellites are indeed in space, but radio waves are not sound waves they are a form of light. Light can travel in a vacuum so the messages that satellites beam back to Earth are light waves not sound waves, that is why it is possible.
If it starts from 0m/s...
s=?
u=0
a=-10
t=8
s=ut +1/2at^2
so s=(0×8)+ (0.5×-10×64)
s=0+(32×-10)
s=32×-10
s=-320metres
