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 to force it into an object, which is applied by the screwdriver rotating around its axis to the drives on the head.
Rotation or rotational motion is the circular movement of an object around a central line, known as an axis of rotation. A plane figure can rotate in either a clockwise or counterclockwise sense around a perpendicular axis intersecting anywhere inside or outside the figure at a center of rotation. A solid figure has an infinite number of possible axes and angles of rotation, including chaotic rotation, in contrast to rotation around a fixed axis.
In fluid dynamics, a vortex is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids, and may be observed in smoke rings, whirlpools in the wake of a boat, and the winds surrounding a tropical cyclone, tornado or dust devil.
A spinning top, or simply a top, is a toy with a squat body and a sharp point at the bottom, designed to be spun on its vertical axis, balancing on the tip due to the gyroscopic effect.
Whitewater kayaking is an outdoor adventure sport where paddlers navigate a river in a specially designed kayak. Whitewater kayaking includes several styles: river running, creeking, slalom, playboating, and squirt boating. Each style offers a different way to experience the thrill and beauty of whitewater environments. Various techniques help paddlers navigate rivers, such as paddle strokes, rolling, and boofing. Whitewater kayaking requires much essential equipment to make a “kayaking kit,” such as a whitewater-specific kayak, spray skirt, paddle, helmet, and PFD.
The Kerr metric or Kerr geometry describes the geometry of empty spacetime around a rotating uncharged axially symmetric black hole with a quasispherical event horizon. The Kerr metric is an exact solution of the Einstein field equations of general relativity; these equations are highly non-linear, which makes exact solutions very difficult to find.
A rotating black hole is a black hole that possesses angular momentum. In particular, it rotates about one of its axes of symmetry.
In physics, there is a speculative hypothesis that if there were a black hole with the same mass, charge and angular momentum as an electron, it would share other properties of the electron. Most notably, Brandon Carter showed in 1968 that the magnetic moment of such an object would match that of an electron. This is interesting because calculations ignoring special relativity and treating the electron as a small rotating sphere of charge give a magnetic moment roughly half the experimental value.
A ring singularity or ringularity is the gravitational singularity of a rotating black hole, or a Kerr black hole, that is shaped like a ring.
Rotation around a fixed axis or axial rotation is a special case of rotational motion around an axis of rotation fixed, stationary, or static in three-dimensional space. This type of motion excludes the possibility of the instantaneous axis of rotation changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rotation theorem, simultaneous rotation along a number of stationary axes at the same time is impossible; if two rotations are forced at the same time, a new axis of rotation will result.
The cat righting reflex is a cat's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3–4 weeks of age, and is perfected at 6–9 weeks. Cats are able to do this because they have an unusually flexible backbone and no functional clavicle (collarbone). The tail seems to help but cats without a tail also have this ability, since a cat mostly turns by moving its legs and twisting its spine in a certain sequence.
A Feynman sprinkler, also referred to as a Feynman inverse sprinkler or reverse sprinkler, is a sprinkler-like device which is submerged in a tank and made to suck in the surrounding fluid. The question of how such a device would turn was the subject of an intense and remarkably long-lived debate. The device generally remains steady with no rotation, though with sufficiently low friction and high rate of inflow, it has been seen to turn weakly in the opposite direction of a conventional sprinkler.
The magnetorotational instability (MRI) is a fluid instability that causes an accretion disk orbiting a massive central object to become turbulent. It arises when the angular velocity of a conducting fluid in a magnetic field decreases as the distance from the rotation center increases. It is also known as the Velikhov–Chandrasekhar instability or Balbus–Hawley instability in the literature, not to be confused with the electrothermal Velikhov instability. The MRI is of particular relevance in astrophysics where it is an important part of the dynamics in accretion disks.
Algodoo is a physics-based 2D freeware sandbox from Algoryx Simulation AB as the successor to the popular physics application Phun. It was released on September 1, 2009 and is presented as a learning tool, an open-ended computer game, an animation tool, and an engineering tool.
An acrobatic flip is a sequence of body movements in which a person leaps into the air and rotates one or more times while airborne. Acrobatic flips are commonly performed in acro dance, free running, gymnastics, cheerleading, high jumping, tricking, goal celebrations, and various other activities. This contrasts with freestyle BMX flips, where a person rotates in the air along with a bicycle.
The length of the day (LOD), which has increased over the long term of Earth's history due to tidal effects, is also subject to fluctuations on a shorter scale of time. Exact measurements of time by atomic clocks and satellite laser ranging have revealed that the LOD is subject to a number of different changes. These subtle variations have periods that range from a few weeks to a few years. They are attributed to interactions between the dynamic atmosphere and Earth itself. The International Earth Rotation and Reference Systems Service monitors the changes.
This glossary of physics is a list of definitions of terms and concepts relevant to physics, its sub-disciplines, and related fields, including mechanics, materials science, nuclear physics, particle physics, and thermodynamics. For more inclusive glossaries concerning related fields of science and technology, see Glossary of chemistry terms, Glossary of astronomy, Glossary of areas of mathematics, and Glossary of engineering.
The Harlem Shake is an Internet meme in the form of a video in which a group of people dance to a short excerpt from the song "Harlem Shake". The meme became viral in early February 2013, with thousands of "Harlem Shake" videos being made and uploaded to YouTube every day at the height of its popularity.
In baseball, a bat flip is the throwing of a baseball bat in such a way that it rotates several times before landing. It is typically done by a batter to show off after hitting a home run. This is in contrast to the usual practice of dropping the bat straight down as the batter begins running to first base.
Glugging is the physical phenomenon which occurs when a liquid is poured rapidly from a vessel with a narrow opening, such as a bottle. It is a facet of fluid dynamics.
