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Falling Bodies
A set of equations describing the trajectories of objects subject to a constant gravitational force under normal Earth-bound conditions. Assuming constant acceleration ''g'' due to Earth's gravity, Newton's law of universal gravitation simplifies to ''F'' = ''mg'', where ''F'' is the force exerted on a mass ''m'' by the Earth's gravitational field of strength ''g''. Assuming constant ''g'' is reasonable for objects falling to Earth over the relatively short vertical distances of our everyday experience, but is not valid for greater distances involved in calculating more distant effects, such as spacecraft trajectories. History Galileo was the first to demonstrate and then formulate these equations. He used a ramp to study rolling balls, the ramp slowing the acceleration enough to measure the time taken for the ball to roll a known distance. He measured elapsed time with a water clock, using an "extremely accurate balance" to measure the amount of water.See the works of Stillman D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Equation
In mathematics, an equation is a mathematical formula that expresses the equality of two expressions, by connecting them with the equals sign . The word ''equation'' and its cognates in other languages may have subtly different meanings; for example, in French an ''équation'' is defined as containing one or more variables, while in English, any well-formed formula consisting of two expressions related with an equals sign is an equation. Solving an equation containing variables consists of determining which values of the variables make the equality true. The variables for which the equation has to be solved are also called unknowns, and the values of the unknowns that satisfy the equality are called solutions of the equation. There are two kinds of equations: identities and conditional equations. An identity is true for all values of the variables. A conditional equation is only true for particular values of the variables. The " =" symbol, which appears in every equati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Meters Per Second Squared
The metre per second squared or metre per square second is the unit of acceleration in the International System of Units (SI). As a derived unit, it is composed from the SI base units of length, the metre, and of time, the second. Its symbol is written in several forms as m/s2, m·s−2 or ms−2, , or less commonly, as (m/s)/s. As acceleration, the unit is interpreted physically as change in velocity or speed per time interval, i.e. metre per second per second and is treated as a vector quantity. Example When an object experiences a constant acceleration of one metre per second squared (1 m/s2) from a state of rest, it achieves the speed of 5 m/s after 5 seconds and 10 m/s after 10 seconds. The average acceleration ''a'' can be calculated by dividing the speed ''v'' (m/s) by the time ''t'' (s), so the average acceleration in the first example would be calculated: :a = \frac = \frac = 1\text = 1\text^2. Related units Newton's second law states that force equals m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Equations Of Motion
In physics, equations of motion are equations that describe the behavior of a physical system in terms of its motion as a function of time. More specifically, the equations of motion describe the behavior of a physical system as a set of mathematical functions in terms of dynamic variables. These variables are usually spatial coordinates and time, but may include momentum components. The most general choice are generalized coordinates which can be any convenient variables characteristic of the physical system. The functions are defined in a Euclidean space in classical mechanics, but are replaced by curved spaces in relativity. If the dynamics of a system is known, the equations are the solutions for the differential equations describing the motion of the dynamics. Types There are two main descriptions of motion: dynamics and kinematics. Dynamics is general, since the momenta, forces and energy of the particles are taken into account. In this instance, sometimes the term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Two New Sciences
The ''Discourses and Mathematical Demonstrations Relating to Two New Sciences'' ( ) published in 1638 was Galileo Galilei's final book and a scientific testament covering much of his work in physics over the preceding thirty years. It was written partly in Italian and partly in Latin. After his '' Dialogue Concerning the Two Chief World Systems'', the Roman Inquisition had banned the publication of any of Galileo's works, including any he might write in the future. After the failure of his initial attempts to publish ''Two New Sciences'' in France, Germany, and Poland, it was published by Lodewijk Elzevir who was working in Leiden, South Holland, where the writ of the Inquisition was of less consequence (see House of Elzevir). Fra Fulgenzio Micanzio, the official theologian of the Republic of Venice, had initially offered to help Galileo publish the new work there, but he pointed out that publishing the ''Two New Sciences'' in Venice might cause Galileo unnecessary trouble; ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Centripetal Force
Centripetal force (from Latin ''centrum'', "center" and ''petere'', "to seek") is the force that makes a body follow a curved trajectory, path. The direction of the centripetal force is always orthogonality, orthogonal to the motion of the body and towards the fixed point of the instantaneous osculating circle, center of curvature of the path. Isaac Newton coined the term, describing it as "a force by which bodies are drawn or impelled, or in any way tend, towards a point as to a centre". In Newtonian mechanics, gravity provides the centripetal force causing astronomical orbits. One common example involving centripetal force is the case in which a body moves with uniform speed along a circular path. The centripetal force is directed at right angles to the motion and also along the radius towards the centre of the circular path. The mathematical description was derived in 1659 by the Dutch physicist Christiaan Huygens. Formula From the kinematics of curved motion it is known ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Standard Gravitational Parameter
The standard gravitational parameter ''μ'' of a celestial body is the product of the gravitational constant ''G'' and the mass ''M'' of that body. For two bodies, the parameter may be expressed as , or as when one body is much larger than the other: \mu=G(M+m)\approx GM . For several objects in the Solar System, the value of ''μ'' is known to greater accuracy than either ''G'' or ''M''. The SI unit of the standard gravitational parameter is . However, the unit is frequently used in the scientific literature and in spacecraft navigation. Definition Small body orbiting a central body The central body in an orbital system can be defined as the one whose mass (''M'') is much larger than the mass of the orbiting body (''m''), or . This approximation is standard for planets orbiting the Sun or most moons and greatly simplifies equations. Under Newton's law of universal gravitation, if the distance between the bodies is ''r'', the force exerted on the smaller body is: F = ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Radial Trajectory
In astrodynamics and celestial mechanics a radial trajectory is a Kepler orbit with zero angular momentum. Two objects in a radial trajectory move directly towards or away from each other in a straight line. Classification There are three types of radial trajectories (orbits). * Radial elliptic trajectory: an orbit corresponding to the part of a degenerate ellipse from the moment the bodies touch each other and move away from each other until they touch each other again. The relative speed of the two objects is less than the escape velocity. This is an elliptic orbit with semi-minor axis = 0 and eccentricity = 1. Although the eccentricity is 1, this is not a parabolic orbit. If the coefficient of restitution of the two bodies is 1 (perfectly elastic) this orbit is periodic. If the coefficient of restitution is less than 1 (inelastic) this orbit is non-periodic. * Radial parabolic trajectory, a non-periodic orbit where the relative speed of the two objects is always equal to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gravitational Constant
The gravitational constant is an empirical physical constant involved in the calculation of gravitational effects in Sir Isaac Newton's law of universal gravitation and in Albert Einstein's general relativity, theory of general relativity. It is also known as the universal gravitational constant, the Newtonian constant of gravitation, or the Cavendish gravitational constant, denoted by the capital letter . In Newton's law, it is the proportionality constant connecting the gravitational force between two bodies with the product of their masses and the inverse-square law, inverse square of their distance. In the Einstein field equations, it quantifies the relation between the geometry of spacetime and the energy–momentum tensor (also referred to as the stress–energy tensor). The measured value of the constant is known with some certainty to four significant digits. In SI units, its value is approximately The modern notation of Newton's law involving was introduced i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gravity (earth)
The gravity of Earth, denoted by , is the net force, net acceleration that is imparted to objects due to the combined effect of gravitation (from mass distribution within Earth) and the centrifugal force (from the Earth's rotation). It is a Euclidean vector, vector quantity, whose direction coincides with a plumb bob and strength or magnitude is given by the Euclidean norm, norm g=\, \mathit\, . In International System of Units, SI units, this acceleration is expressed in metre per second squared, metres per second squared (in symbols, metre, m/second, s2 or m·s−2) or equivalently in Newton (unit), newtons per kilogram (N/kg or N·kg−1). Near Earth's surface, the acceleration due to gravity, accurate to 2 significant figures, is . This means that, ignoring the effects of drag (physics), air resistance, the speed of an object free fall, falling freely will increase by about every second. The precise strength of Earth's gravity varies with location. The agreed-upon value for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Peregrine Falcon
The peregrine falcon (''Falco peregrinus''), also known simply as the peregrine, is a Cosmopolitan distribution, cosmopolitan bird of prey (raptor) in the family (biology), family Falconidae renowned for its speed. A large, Corvus (genus), crow-sized falcon, it has a blue-grey back, barred white underparts, and a black head. As is typical for avivore, bird-eating (avivore) raptors, peregrine falcons are Sexual dimorphism, sexually dimorphic, with females being considerably larger than males. Historically, it has also been known as "black-cheeked falcon" in Australia, and "duck hawk" in North America. The breeding range includes land regions from the Arctic tundra to the tropics. It can be found nearly everywhere on Earth, except extreme polar regions, very high mountains, and most tropical rainforests; the only major ice-free landmass from which it is entirely absent is New Zealand. This makes it the world's most widespread Raptor (bird), raptor and one of the most widely found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Freeflying
Free flying is a skydiving discipline that began in the late 1980s, involving falling free in various vertical orientations, as opposed to the traditional "belly-to-earth" orientation. The discipline is known to have originated when Olav Zipser began experimenting with non-traditional forms of Body flight. Zipser founded the Free Fly Clowns as a two-person competitive team with Mike Vail in 1992. He was joined by Omar Alhegelan (1st ever FAI Freestyle World Cup & World Champion), Charles Bryan, and Stefania Martinengo in 1994. The Free Fly Clowns are also credited with opening the first school to teach free flying, The First School of Modern Skyflying. Free flying entered public awareness in 1996 when the SSI Pro Tour added free flying as a three-person competitive discipline at the second televised event (with Skysurfing), part of ESPN's Destination Extreme series. One-hundred and fifty countries watched the Free Fly Clowns (Olav Zipser, Charles Bryan and Omar Alhegelan) as t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
