Daily Archives: January 22, 2009
It's Cold in Here, Mr. Bigglesworth!
Experimental insights: Leak detection
How do you make a seal which does not freeze up at Liquid Helium temperatures? The trick is to use the extremely malleable metal Indium – which remains slightly squishy at low temperatures. Indium is seriously fun to play with, it’s a bit like metallic plasticine.
Peer Pressure
C’mon … we’ve all done it!
Just about anyone with access to liquid nitrogen has dunked things and smashed them.
Cheez Wiz is a Condiment?
Got Stress? It Makes Me Tensor and Tensor!
Everyday physics: the stress tensor
This is very similar to the notion of pressure, as described in the previous post on flotation. Indeed, the units of stress and the units of pressure are the same. The main difference, however, is that the stress is more directional than pressure. So in the picture of the cables above, the force is proportional to the area in the yz plane (the cross sectional area), while the force points in the x direction. However, if we though about it in the vertical direction, the cables are not that good at transmitting force in that direction, so we would expect that the force per unit area going upwards is different. This is on contrast with pressure that goes into all directions at once.