Bennett Science Blog

If you're going to spend time watching videos on YouTube, why not learn something while you're at it? Whether you like slow-motion videos of explosions, crazy chemistry and physics demos, or simple explanations of complex science concepts, the following 10 YouTube channels are worth your subscription. By Amber Bennett   1. Physics Girl Source: YouTube/Physics Girl Dianna Cowern's  Physics Girl  channel features demos, experiments, and other cool stuff (be sure to check out her 1,800-mile test drive of a hydrogen fuel cell car ). If you have just started studying physics or would like to brush up on the basics, we recommend starting with this playlist . 2. Vsauce Source: YouTube/Vsauce Michael Stevens' Vsauce channel covers a wide variety of subjects, including space, art, physics, and human behavior. His physics videos answer such questions as " Which way is down ?" and " How much does a shadow weigh ?" You can check out his physics videos on this p...

Photo Credit: YouTube Screenshot By Andrew Bennett The Cavendish gravity experiment requires us to be able to measure how much a hanging bar rotates when we place heavy weights nearby. In order to determine a reliable value for G, the gravitational constant, we must first measure the shift angle very precisely. In this video, I build a protractor with a 3-meter radius that can measure angular shifts of as little as one one-thousandth of a radian. That's less than 0.06   degrees or about 3.5 minutes of arc! How I Built My Protractor The design is pretty straightforward but is extremely labor-intensive to construct one this size. I start by making a circular wall to use as the surface of the protractor made of thin, white, flexible pressed wood. I glued some pieces of 2x4 to my garage floor and used a router to cut a groove that the wall will fit into. To make the groove along a circle, I first traced out the circle on the wood by attaching a marker to a long wire, which the...

Image Credit: Wikimedia Commons By Andrew Bennett As I'm using radians as my unit of measure for all angles in my Cavendish experiment, I thought some background might be useful for some of my readers. So, let's get right to it. What Is a Radian? Simply put, a radian is a unit for measuring angles. Imagine a big circle drawn on the ground in chalk. Use your chalk to draw a straight line from the center of the circle to the edge, and measure that line (the radius of the circle). Now, walk that same distance around the outside of the circle (if the circle has a radius of 5 meters, walk for 5 meters on the edge). Draw a new line from the edge of the circle where you are standing back to the middle. The two lines you've drawn have an angle between them that we define to be equal to 1 radian. Instead, if we had walked along the outside of the circle for a distance equal to 2 times the radius, then the lines we drew would have had an angle between them equal to 2 radi...