A back lever is a static hold performed on the rings or the pull-up bar. A back lever is rated as an 'A' value skill on the Code of Points, a scale from A to F, with F being the most difficult.
A back lever is performed by lowering from an inverted hang until the gymnast's body is parallel to the ground and facing towards the floor.
Performing a back lever requires a high degree of strength in the back and biceps, a lot of core tension must be generated to stay horizontal.
The world record is held by the Spanish Joan Romero with 73 seconds.
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors that take into account departures from the ideal.
A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that use mechanical advantage to multiply force. Usually the term refers to the six classical simple machines that were defined by Renaissance scientists:
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force. The symbol for torque is typically , the lowercase Greek letter tau. When being referred to as moment of force, it is commonly denoted by M. Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque, which is applied by the screwdriver rotating around its axis. A force of three newtons applied two metres from the fulcrum, for example, exerts the same torque as a force of one newton applied six metres from the fulcrum.
A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists. A lever amplifies an input force to provide a greater output force, which is said to provide leverage, which is mechanical advantage gained in the system, equal to the ratio of the output force to the input force. As such, the lever is a mechanical advantage device, trading off force against movement.
An operant conditioning chamber is a laboratory apparatus used to study animal behavior. The operant conditioning chamber was created by B. F. Skinner while he was a graduate student at Harvard University. The chamber can be used to study both operant conditioning and classical conditioning.
Calisthenics or callisthenics is a form of strength training that utilizes an individual's body weight as resistance to perform multi-joint, compound movements with little or no equipment.
The Beretta Cheetah, also known by its original model name of "Series 81", or "80 Series", is a line of compact blowback operated semi-automatic pistols designed and manufactured by Beretta of Italy. They were introduced in 1976 and include models in .32 ACP, .380 ACP and .22 LR. Production paused in 2017, but Beretta revived the marque in 2023 with the release of the 80X.
A pocket watch is a watch that is made to be carried in a pocket, as opposed to a wristwatch, which is strapped to the wrist.
Kick start is a method of starting an internal combustion engine by pushing a ratcheting lever with the rider's foot. Kick start mechanisms were almost universally a part of motorcycle engines before the mid-1970s, and were phased out of production over the next twenty years or so as electric starters became standard equipment. There are still some motorcycles produced that have both kick and electric starters.
The Henry repeating rifle is a lever-action tubular magazine rifle. It is famous for having been used at the Battle of the Little Bighorn and having been the basis for the iconic Winchester rifle of the American Wild West.
Johnny Lever is an Indian actor and comedian who is known for his works in Hindi cinema. He is one of the first and most recognised comedians in India. He is the recipient of numerous accolades, including thirteen Filmfare Awards nominations in Filmfare Award for Best Performance in a Comic Role, and has won the award twice, for his work in Deewana Mastana (1997) and Dulhe Raja (1998). He began his career in 1984, and has acted in more than three hundred Hindi films.
Shaping is a conditioning paradigm used primarily in the experimental analysis of behavior. The method used is differential reinforcement of successive approximations. It was introduced by B. F. Skinner with pigeons and extended to dogs, dolphins, humans and other species. In shaping, the form of an existing response is gradually changed across successive trials towards a desired target behavior by reinforcing exact segments of behavior. Skinner's explanation of shaping was this:
We first give the bird food when it turns slightly in the direction of the spot from any part of the cage. This increases the frequency of such behavior. We then withhold reinforcement until a slight movement is made toward the spot. This again alters the general distribution of behavior without producing a new unit. We continue by reinforcing positions successively closer to the spot, then by reinforcing only when the head is moved slightly forward, and finally only when the beak actually makes contact with the spot. ... The original probability of the response in its final form is very low; in some cases it may even be zero. In this way we can build complicated operants which would never appear in the repertoire of the organism otherwise. By reinforcing a series of successive approximations, we bring a rare response to a very high probability in a short time. ... The total act of turning toward the spot from any point in the box, walking toward it, raising the head, and striking the spot may seem to be a functionally coherent unit of behavior; but it is constructed by a continual process of differential reinforcement from undifferentiated behavior, just as the sculptor shapes his figure from a lump of clay.
The Canon FT QL is a 35mm single-lens reflex camera introduced by Canon Inc. in March 1966. It has a Canon FL lens mount compatible with the large range of FL series lenses. The FT can also operate the later Canon FD series lenses in stop-down mode, but the earlier R series has a different lens aperture mechanism and cannot be used, although the bayonet fitting is similar. The standard kit lenses were Canon's 50mm f/1.8 ; 50mm f/1.4 and 58mm f/1.2, the body-only option was offered later.
The Bell Rocket Belt is a low-power rocket propulsion device that allows an individual to safely travel or leap over small distances. It is a type of rocket pack.
The Colt Model 1848 Percussion Army Revolver is a .44 caliber revolver designed by Samuel Colt for the U.S. Army's Regiment of Mounted Rifles. The revolver was also issued to the Army's "Dragoon" regiments. This revolver was designed as a solution to numerous problems encountered with the Colt Walker. Although it was introduced after the Mexican–American War, it became popular among civilians during the 1850s and 1860s and was also used during the American Civil War.
Locking pliers are pliers that can be locked into position, using an "over-center" cam action. Locking pliers are available with many different jaw styles, such as needle-nose pliers, wrenches, clamps and various shapes to fix metal parts for welding. They also come in many sizes.
The front lever is a gymnastic and calisthenic move - a static hold normally performed on the still rings or the pull-up bar. A front lever is performed by lowering from an inverted hang until the body is completely horizontal and straight with the front of the body facing upwards. An accomplished gymnast may also pull directly into the horizontal position from a dead hang. Front levers require a high degree of back and core strength.
A marine steam engine is a steam engine that is used to power a ship or boat. This article deals mainly with marine steam engines of the reciprocating type, which were in use from the inception of the steamboat in the early 19th century to their last years of large-scale manufacture during World War II. Reciprocating steam engines were progressively replaced in marine applications during the 20th century by steam turbines and marine diesel engines.
A machine fly, alternatively called a seated lever fly or "pec deck" fly is a strength training exercise based on the free weight chest fly. As with the chest fly, the hand and arm move through an arc while the elbow is kept at a constant angle. Flyes are used to work the muscles of the upper body, primarily the sternal head of the pectoralis major. Because these exercises use the arms as levers at their longest possible length, the amount of weight that can be moved is significantly less than equivalent press exercises for the same muscles. Denie Walter is credited with calling it the Peck Dec back in the 1970s.
The Minolta SR-2 was presented in 1958 as the first 35mm SLR camera from Chiyoda Kogaku. Popular cameras of this type at that time were mainly from Europe but a few from Japan, including the Asahi Pentax, the Miranda T and the Topcon R. The miniature SLR camera concept was conceived in the 1930s at Ihagee in Dresden, resulting in the 1936 Kine Exakta. Influential cameras designs like that of the 1939 KW Praktiflex, the 1949 ZI Contax S, and 1952 the KW Praktina marked the steady progress toward a perfected SLR. Several features of the latter seem to have influenced the design of the SR-2 although dissimilar in many respects. The obvious similarities are the stepped top plate, the carrying strap lugs, the self-timer lever and some general body features.
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