In the interesting video below, Derek Muller from the YouTube Channel Veritasium explains some basics regarding the measuring of radioactivity, and then he visits some of the most radioactive places on Earth with his Geiger counter in tow. At the end of the video, Derek talks about the amount of radiation he would have received if he had stayed in the most radioactive place he visited for one hour and reveals that it pales in comparison to the amount of radioactivity received by people living in some locations or engaging in certain activities. One of these activities, which is sadly still extremely common, exposes a part of the body to the greatest amount of radiation regularly received by human beings nowadays. Watch the video to find out what activity is this!
Tensegrity structures are structures where the physical integrity of the structure depends on tensional forces rather than the common compressive forces that maintain the integrity of structures such as buildings. The name was coined by the renowned American architect Buckminster Fuller famous for the invention of the geodesic dome. Most tensegrity structures consist of rigid materials such as rods or blocks attached to each other by cords or cables, where the weight of the rigid materials creates tension on the cables which keeps the rigid materials in place. The apparent distribution in space of the rigid materials of tensegrity structures often seems to defy gravity, and many such structures have been produced for entertainment or as works of art or architecture. However, the principles of tensegrity structures are also found at work in biology such as in the interplay between muscles, bones, and tendons, and even in the cytoskeletons of cells.
In the video below, the folks of the YouTube channel Home Science display a tensegrity structure and show how to build it.
The physical forces acting upon bullets travelling through water are very different from those acting upon bullets travelling through air due to the much higher friction of the liquid medium. This fact allowed Norwegian physicist Andreas Wahl to shoot himself with a rifle in a pool and survive as shown in the video below.
Firing guns underwater produces interesting effects that are explored in the video below by Destin from the YouTube channel SmarterEveryday. He shoots an AK-47 rifle underwater and explains some of the science involved in the effects.
Several approaches have been used to increase the distance that bullets can travel underwater from the APS underwater riffle to supercavitating ammo.
Skydiving and base jumping are among the most adrenaline-releasing sports. In these disciplines individuals jump from a plane, a cliff, or a structure, and after falling for a certain amount of time they open a parachute. One modality of these sports involves wearing a wingsuit. A wingsuit is a garment with stretches of fabric that extend between the legs and between the arms and the legs in a design akin to the skin folds of flying squirrels. The wingsuit essentially turns the human body into a wing producing a certain amount of lift that allows flyers to move forward up to 2 or 3 units of distance for each unit of distance that they fall. Wingsuit flyers can achieve forwards speeds of up to 100 miles per hour or more.
A wingsuit flight ends with the opening of a parachute, so in principle wingsuit flying should be no more dangerous than skydiving or base jumping. However the real allure of wingsuit flying is proximity flying. This is when the flyers fly at speeds upwards of 70 miles per hour next to cliff faces or very close to the ground and even through geological formations. This has made wingsuit flying a very dangerous sport that has claimed the lives of many individuals including some of the top performing flyers in the world.
Italian wingsuit flyer Uli Emanuele won the Base Jump World Championship held in Spain in 2010 leaving all the professionals of the sport behind. Uri went on to take the world by storm with his daring jumps and stunts winning him a huge fan base. In the video below Uri performs one of the most extreme stunts ever attempted by flying through a 6 feet wide opening in a rock in Lauterbrunnen, Switzerland, in 2014. One of the amazing things about this stunt that is not obvious from the video is that he repeated it 3 more times!
Emanuele died in 2016 at the age of 30 while flying in the Dolomite Mountains in Switzerland when he lost control and crashed into rocks before he could open his parachute. He is part of a long list of wingsuit proximity flyers such as Alexander Polli, Graham Dickinson, and Dean Potter who have lost their lives practicing this dangerous sport.
Skunks and their peculiar defense system have generated many cultural references in human societies, and the chemical components of their spray that give it its distinctive smell have been studied by scientists. Anna Rothschild from the YouTube channel Gross Science tells us in the video below all we ever wanted (and not wanted) to know about skunk spray. The video stinks, but that’s a compliment!