On this day in physics: 06 February 1802- Happy Birthday to Charles Wheatstone, a physicist who invented a myriad of things including the concertina and the stereoscope. A stereoscope is kind of like a viewfinder that children play with. A card will contain slightly different variations of the same image which when looked through the viewfinder produce a 3D image.
Word of the Day: Escape Velocity- the least velocity required in order to for an object to free itself from the gravitational attraction of a massive object. Objects which are traveling less than the escape velocity in range of a massive object orbit it. Example: The Earth is traveling less than its escape Velocity of the sun, and so the Earth orbits the Sun. Now, the escape velocity is dependent on the mass of the object you're trying to escape, and the distance you are from that object. The equation for the escape velocity is actually sqrt(2GM/r), where G is the gravitational constant G = 6.67×10−11 m^3kg^−1s^−2, M is the mass of the object to be escaped and r is the distance from that mass. Here are some examples of what escape velocities might look like.[Source] From the Sun's surface, you would need to be traveling 618 km/s to escape its gravitational clutches. From Earth, you would need to be traveling 11 km/s to escape Earth's gravity, and 42 km/s to escape the Sun's. At Jupiter, the tables turn. You would need to be traveling only only 18.5 km/s to escape the hold of the Sun, but 60 km/s to slip the grip of Jupiter itself. Lastly, from Neptune, 7.7 km/s to escape the Sun, and 24 km/s to escape Neptune itself. The escape velocity of anything at the event horizon of a black hole is the speed of light. Past the event horizon, there is no escape.
Quote of the Day: "Once someone gets a little escape velocity going, ain't no play in the world that will keep them from leaving." -Junot Diaz, Drowned
Keywords: Escape, Velocity, Mass, Gravity, Distance, Sun, Earth.
