Topic
Metals
3 articles
Physics
Why does metal feel colder than wood?
A metal chair leg and a wooden tabletop stand in the same room, in the same air, at the same temperature. Touch them one after the other and your hand insists that one of them is freezing. Your hand is not lying — but it is not measuring what you think it is.
Chemistry
Why does rust make iron swell and crack?
The orange patch on a painted gate does not sink into the metal. It bulges, and the paint around it stands up in a blister that crackles under a fingernail.
Technology
Why does a lightbulb blow the moment you switch it on?
Bulbs almost never quit while they are quietly glowing. They wait for the flick of a switch, then go with a flash and a small tink. Something about that first instant is rougher on the wire than a whole evening of burning.