Gesamtlänge aller Episoden: 2 days 15 hours 43 minutes
Can sound kill? Inspired by a Kate Bush song, we ask whether sonic weapons could work.
What is fire? Is it a solid, liquid or a gas? Adam Rutherford and Hannah Fry investigate.
'How far up can a helium balloon go? Could it go out to space?' asks Juliet Gok, aged 9.