Answer:
The answer to your question is: v = 121.46 m/s
Explanation:
Data
h = 30 m
vo = ?
dx = 300 m
Formula
t = 
speed = distance / time
Process

t= 2.47 s
speed = 300 / 2.47
speed = v = 121.46 m/s
An asteroid in the asteroid belt
It is a supernova that is thought to be a result of a explosion of a carbon-oxygen white dwarf in a binary system.
-- <em>Mechanical waves DO</em> require a medium in order to travel from place to place. (Sound can't travel without some material to travel through on the way.)
-- <em>Electromagnetic waves do NOT</em> need a medium in order to travel from place to place. (Sunlight reaches us from the Sun without anything to travel through on the way.)