It would reach hypersonic speeds -- five times the speed of sound.
VOA: special.2010.07.07
There are also quotes from a madrigal by the Italian baroque composer, Claudio Monteverdi, which sound just out of reach just beneath an only partially penetrable, dark surface.
Mrs Philpotts' mother, who lived with the family, said she had heard an explosion and the sound of broken glass but had been unable to reach her daughter because of thick smoke.