Page 85 - BBC Focus - August 2017

If your champagne
glasses are grubby,
bubbles will form on
the specks of dirt,
betraying your shoddy
washing-up skills

Why do champagne bubbles rise from the
bottom of a glass?
EWAN HAMISH, NOTTINGHAMSHIRE

The bubbles are filled with carbon dioxide (CO 2 ), a gas 800
times less dense than the surrounding liquid. Molecules
of this gas accumulating in imperfections in the glass and
start to form a bubble, whose low density supplies enough
buoyancy to break off and float towards the surface. In the
process they run into more molecules, making the bubble even
bigger and more buoyant, and accelerating its ascent. RM

Why does 37°C feel
so hot when our
bodies are at that
temperature already?
SIMON LEYLAND, LINCOLN

That’s the temperature of your core.
Your skin is usually around 34°C
and your face, fingers and toes can
be much colder. The receptors in
your skin react to differences in
temperature, so when you put your
Love our Q&A hand on your bare stomach, your
pages? Follow our hand registers warmth but your
Twitter feed belly shrieks ‘cold!’, even
@sciencefocusQA though both are ‘skin
temperature’. Similarly, the
inside of your mouth feels
warm to your finger, but not
to your tongue. LV

85
85