Ferrofluid on top of a strong magnet forms peaks which follow the magnetic field.
Like athletes in many of the gravity sports in the Winter Olympics, lugers want to be as aerodynamic as possible to minimize their drag. Once a luger has started sliding, only gravity can increase their speed - every other force, from friction to drag, pulls away valuable time. Luge sleds are built on sharp runners and athletes slide feet-first in a position much more streamlined than the head-first position of skeleton. Both contribute to the much higher speeds in luge - up to 140 kph (87 mph). Luge is also the only sliding sport measured down to thousandths of a second, so every gram of drag* makes a difference. Lugers keep their heads pulled back and wear full helmets to keep the air flow consistent and attached as much as possible. It is also typical for them to spend time in the wind tunnel, testing their sled’s aerodynamics, adjusting their position, and even testing their suits. (Photo credit: S. Botterill)
* For those wondering, yes, drag is a force and a gram is a unit of mass, not force. However, it is not unusual when testing athletes in wind tunnels to compare drag between configurations in terms of grams.
FYFD is celebrating the Games with a series on fluid dynamics in the Winter Olympics. Stay tuned for more!
False-colour image of a laser beam exhibiting a superposition of 10 right-handed and 10 left-handed quanta of orbital angular momenta, making 10 + 10 = 20 bright spots on the inner ring. Photons in such modes rotate simultaneously clockwise and anticlockwise.
An extraordinary but fundamental feature of quantum world: quantum entanglement.
Credits: Robert Fickler, University of Vienna
What kind of condenser is this? A dry ice - acetone cooled!
Dry ice in acetone (-78,5 °C) is placed between the walls of the condenser and if the flask contains some ammonia, it won’t let is escape.
To get ions to fly in a predictable way, you need to remove a lot of air from your mass spectrometer. Most mass analyzers will not work at pressures higher than 10^-9 bar (0.000000001 bar), that’s a billion times less than atmospheric pressure (1 bar).
To achieve these pressures a couple different pumps are used. A first pump drops the pressure to 0.0001 bar. After this, the highly sensitive turbomolecular pump (pictured) lowers the pressure down to operating levels. A turbomolecular pump is so sensitive that it will not work until the roughing pump first removes most of the air.