Acceleration

Acceleration, in physics, is the rate of change of velocity of an object. An object's acceleration is the net result of any and all forces acting on the object, as described by Newton's Second Law. The SI unit for acceleration is metre per second squared (m s^-2). Accelerations are vector quantities (they have magnitude and direction) and add according to the parallelogram law. As a vector, the calculated net force is equal to the product of the object's mass (a scalar quantity) and its acceleration.

For example, when a car starts from a standstill (zero relative velocity) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the car turns, there is an acceleration toward the new direction. In this example, we can call the forward acceleration of the car a "linear acceleration", which passengers in the car might experience as a force pushing them back into their seats. When changing direction, we might call this "non-linear acceleration", which passengers might experience as a sideways force. If the speed of the car decreases, this is an acceleration in the opposite direction from the direction of the vehicle, sometimes called deceleration. Passengers may experience deceleration as a force lifting them forwards. Mathematically, there is no separate formula for deceleration: both are changes in velocity. Each of these accelerations (linear, non-linear, deceleration) might be felt by passengers until their velocity (speed and direction) matches that of the car.

Khan Academy

Khan Academy is a non-profit educational organization created in 2006 by educator Salman Khan with the aim of providing a free, world-class education for anyone, anywhere. The organization produces short lectures in the form of YouTube videos. In addition to micro lectures, the organization's website features practice exercises and tools for educators. All resources are available for free to anyone around the world. The main language of the website is English, but the content is also available in other languages.

History

The founder of the organization, Salman Khan, was born in New Orleans, Louisiana, United States to immigrant parents from Bangladesh and India. After earning three degrees from the Massachusetts Institute of Technology (a BS in mathematics, a BS in electrical engineering and computer science, and an MEng in electrical engineering and computer science), he pursued an MBA from Harvard Business School.

In late 2004, Khan began tutoring his cousin Nadia who needed help with math using Yahoo!'s Doodle notepad.When other relatives and friends sought similar help, he decided that it would be more practical to distribute the tutorials on YouTube. The videos' popularity and the testimonials of appreciative students prompted Khan to quit his job in finance as a hedge fund analyst at Connective Capital Management in 2009, and focus on the tutorials (then released under the moniker "Khan Academy") full-time.

Alfa Romeo

Alfa Romeo Automobiles S.p.A. (Italian pronunciation: [ˈalfa roˈmɛːo]) is an Italian car manufacturer. Founded as A.L.F.A. ("Anonima Lombarda Fabbrica Automobili", translating to Anonymous Lombard Automobile Factory in English) on June 24, 1910, in Milan, the company has been involved in car racing since 1911. It was owned by Italian state holding company Istituto per la Ricostruzione Industriale between 1932 and 1986, when it became a part of the Fiat group. In February 2007, the Alfa Romeo brand was transformed into the current Alfa Romeo Automobiles S.p.A., a subsidiary of Fiat Group Automobiles, now Fiat Chrysler Automobiles Italy.

The company that became Alfa Romeo was founded as Società Anonima Italiana Darracq (SAID) in 1906 by the French automobile firm of Alexandre Darracq, with some Italian investors. In late 1909, the Italian Darracq cars were selling slowly and the Italian partners of the company hired Giuseppe Merosi to design new cars. On June 24, 1910, a new company was founded named A.L.F.A., initially still in partnership with Darracq. The first non-Darracq car produced by the company was the 1910 24 HP, designed by Merosi. A.L.F.A. ventured into motor racing, with drivers Franchini and Ronzoni competing in the 1911 Targa Florio with two 24-hp models. In August 1915, the company came under the direction of Neapolitan entrepreneur Nicola Romeo, who converted the factory to produce military hardware for the Italian and Allied war efforts. In 1920, the name of the company was changed to Alfa Romeo with the Torpedo 20-30 HP the first car to be so badged.