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Falling (sensation)
A sensation of falling occurs when the labyrinth or ''vestibular apparatus'', a system of fluid-filled passages in the inner ear, detects changes in acceleration. This sensation can occur when a person begins to fall, which in terms of mechanics amounts to a sudden acceleration increase from zero to roughly 9.81 m/s2. If the body is in free fall with no other momenta, there is no falling sensation. This almost never occurs in real-life falling situations because when the faller leaves their support there are usually very significant quantities of residual momenta such as rotation and these momenta continue as the person falls, causing a sensation of dysphoria. The faller doesn't fall straight down but spins, flips, etc. due to these residual momenta and also due to the asymmetric forces of air resistance on their asymmetric body. While velocity continues to increase, the downward acceleration due to gravity remains constant. Increasing drag force may even cause a feeling of ascent. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sense
A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of Stimulus (physiology), stimuli. Although, in some cultures, five human senses were traditionally identified as such (namely Visual perception, sight, Olfaction, smell, Somatosensory system, touch, taste, and hearing), many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli (such as a sound or smell) for Transduction (physiology), transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought. In organisms, a sensory organ consists of a group of interrelated Sensory neuron, sensory cells that respond to a specific type of physical stimulus. Via Cranial nerves, cranial and spinal nerves (nerves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Labyrinth (inner Ear)
The bony labyrinth (also osseous labyrinth or otic capsule) is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts: the vestibule of the ear, vestibule, semicircular canals, and cochlea. These are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a clear fluid, the perilymph, in which the membranous labyrinth is situated. A Bone fracture, fracture classification system in which temporal bone fractures detected by CT scan, computed tomography are delineated based on disruption of the otic capsule has been found to be predictive for complications of temporal bone trauma such as Facial nerve injuries, facial nerve injury, sensorineural deafness and cerebrospinal fluid otorrhea. On radiographic images, the otic capsule is the densest portion of the temporal bone. In otospongiosis, a leading cause of adult-onset hearing loss, the otic capsule is exclusively affected. This area normally undergoes no remodel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanics
Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of an object's position relative to its environment. Theoretical expositions of this branch of physics has its origins in Ancient Greece, for instance, in the writings of Aristotle and Archimedes (see History of classical mechanics and Timeline of classical mechanics). During the early modern period, scientists such as Galileo Galilei, Johannes Kepler, Christiaan Huygens, and Isaac Newton laid the foundation for what is now known as classical mechanics. As a branch of classical physics, mechanics deals with bodies that are either at rest or are moving with velocities significantly less than the speed of light. It can also be defined as the physical science that deals with the motion of and forces on bodies not in the quantum realm. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravitational Acceleration
In physics, gravitational acceleration is the acceleration of an object in free fall within a vacuum (and thus without experiencing drag (physics), drag). This is the steady gain in speed caused exclusively by gravitational attraction. All bodies accelerate in vacuum at the same rate, regardless of the masses or compositions of the bodies; the measurement and analysis of these rates is known as gravimetry. At a fixed point on the surface, the magnitude of gravity of Earth, Earth's gravity results from combined effect of gravitation and the centrifugal force from Earth's rotation. At different points on Earth's surface, the free fall acceleration ranges from , depending on altitude, latitude, and longitude. A conventional standard gravity, standard value is defined exactly as 9.80665 m/s² (about 32.1740 ft/s²). Locations of significant variation from this value are known as gravity anomaly, gravity anomalies. This does not take into account other effects, such as buoyancy or d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Free Fall
In classical mechanics, free fall is any motion of a physical object, body where gravity is the only force acting upon it. A freely falling object may not necessarily be falling down in the vertical direction. If the common definition of the word "fall" is used, an object moving upwards is not considered to be falling, but using scientific definitions, if it is subject to only the force of gravity, it is said to be in free fall. The Moon is thus in free fall around the Earth, though its orbital speed keeps it in orbit of the Moon, very far orbit from the Earth's surface. In a roughly uniform gravitational field gravity acts on each part of a body approximately equally. When there are no other forces, such as the normal force exerted between a body (e.g. an astronaut in orbit) and its surrounding objects, it will result in the sensation of weightlessness, a condition that also occurs when the gravitational field is weak (such as when far away from any source of gravity). The ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity
In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force between objects and the Earth. This force is dominated by the combined gravitational interactions of particles but also includes effect of the Earth's rotation. Gravity gives weight to physical objects and is essential to understanding the mechanisms responsible for surface water waves and lunar tides. Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circulation of fluids in multicellular organisms. The gravitational attraction between primordial hydrogen and clumps of dark matter in the early universe caused the hydrogen gas to coalesce, eventually condensing and fusing to form stars. At larger scales this results in galaxies and clust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drag (physics)
In fluid dynamics, drag, sometimes referred to as fluid resistance, is a force acting opposite to the direction of motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers, two solid surfaces, or between a fluid and a solid surface. Drag forces tend to decrease fluid velocity relative to the solid object in the fluid's path. Unlike other resistive forces, drag force depends on velocity. Drag force is proportional to the relative velocity for low-speed flow and is proportional to the velocity squared for high-speed flow. This distinction between low and high-speed flow is measured by the Reynolds number. Drag is instantaneously related to vorticity dynamics through the Josephson-Anderson relation. Examples Examples of drag include: * Net force, Net Aerodynamic force, aerodynamic or Fluid dynamics, hydrodynamic force: Drag acting opposite to the direction of movement of a solid object such as cars, aircraft, and boat hulls. * Viscou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Balance Disorder
A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Equilibrioception, Balance is the result of several body systems working together: the visual system (eyes), vestibular system (ears) and proprioception (the body's sense of where it is in space). Degeneration or loss of function in any of these systems can lead to balance deficits. Signs and symptoms Cognitive dysfunction (disorientation) may occur with vestibular disorders. Cognitive deficits are not just spatial in nature, but also include non-spatial functions such as object recognition memory. Vestibular dysfunction has been shown to adversely affect processes of attention and increased demands of attention can worsen the postural sway associated with vestibular disorders. Recent MRI studies also show that humans with bilateral vestibular da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypnagogia
Hypnagogia is the transitional state from wakefulness to sleep, also defined as the waning state of consciousness during the onset of sleep. Its corresponding state is '' hypnopompia'' sleep to wakefulness. Mental phenomena that may occur during this "threshold consciousness" include hallucinations, lucid dreaming, and sleep paralysis. Etymology In 1848, Alfred Maury introduced the term "hypnagogic" from the Greek words ύπνος (“hypnos”), meaning “sleep”, and αγωγός (“agōgos”), meaning “conductor” or “leader”. Later, in 1904, Frederic Myers coined the term "hypnopompic," with its word-ending originating from the Greek word "pompos," meaning "sender." Definitions The word ''hypnagogia'' is sometimes used in a restricted sense to refer to the onset of sleep, and contrasted with '' hypnopompia'', Frederic Myers's term for waking up. However, ''hypnagogia'' is also regularly employed in a more general sense that covers both falling asleep and wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypnic Jerk
A hypnic jerk, hypnagogic jerk, sleep start, sleep twitch, myoclonic jerk, or night start is a brief and sudden involuntary contraction of the muscles of the body which occurs when a person is beginning to fall asleep, often causing the person to jump and awaken suddenly for a moment. Hypnic jerks are one form of involuntary muscle twitches called myoclonus. Physically, hypnic jerks resemble the "jump" experienced by a person when startled, sometimes accompanied by a falling sensation. Hypnic jerks are associated with a rapid heartbeat, quickened breathing, sweat, and sometimes "a peculiar sensory feeling of 'shock' or 'falling into the void. It can also be accompanied by a vivid dream experience or hallucination. A higher occurrence is reported in people with irregular sleep schedules. When they are particularly frequent and severe, hypnic jerks have been reported as a cause of sleep-onset insomnia. Hypnic jerks are common physiological phenomena. Around 70% of people experie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vestibular System
The vestibular system, in vertebrates, is a sensory system that creates the sense of balance and spatial orientation for the purpose of coordinating motor coordination, movement with balance. Together with the cochlea, a part of the auditory system, it constitutes the labyrinth of the inner ear in most Mammal, mammals. As movements consist of rotations and translations, the vestibular system comprises two components: the semicircular canals, which indicate Angular acceleration, rotational movements; and the otoliths, which indicate Acceleration, linear accelerations. The vestibular system sends signals primarily to the neural structures that control eye movement; these provide the anatomical basis of the vestibulo-ocular reflex, which is required for clear vision. Signals are also sent to the muscles that keep an animal upright and in general control Neutral spine, posture; these provide the anatomical means required to enable an animal to maintain its desired position in space. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Live Science
Live Science is a science news website. The publication features stories on a wide range of topics, including space, animals, health, archaeology, human behavior, and planet Earth. It also includes a reference section with links to other websites. Its stated mission is to inform and entertain readers about science and the world around them.{{r, mission History Live Science was originally made in 2004. It was acquired by ediaNetwork, later called Purch, in 2009.{{r, purch Purch consumer brands (including Live Science) were acquired by Future The future is the time after the past and present. Its arrival is considered inevitable due to the existence of time and the laws of physics. Due to the apparent nature of reality and the unavoidability of the future, everything that currently ex ... in 2018. Reception In 2011, the '' Columbia Journalism Review''{{'s "News Startups Guide" called Live Science "a purebred Web animal, primarily featuring one-off stories and photo gall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
