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Radius of curvature and center of curvature. In differential geometry, the radius of curvature, R, is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius of a circle that best fits a normal section or ...
The curvature is the reciprocal of radius of curvature. That is, the curvature is =, where R is the radius of curvature [5] (the whole circle has this curvature, it can be read as turn 2π over the length 2π R). This definition is difficult to manipulate and to express in formulas.
Radius of curvature, the reciprocal of the curvature in differential geometry Minimum railway curve radius , the shortest allowable design radius for the centerline of railway tracks Topics referred to by the same term
The center and radius of the osculating circle at a given point are called center of curvature and radius of curvature of the curve at that point. A geometric construction was described by Isaac Newton in his Principia:
The parameter t in γ(t) can be thought of as representing time, and γ the trajectory of a moving point in space. When I is a closed interval [a,b], γ(a) is called the starting point and γ(b) is the endpoint of γ. If the starting and the end points coincide (that is, γ(a) = γ(b)), then γ is a closed curve or a loop.
The Cesàro equation is obtained as a relation between arc length and curvature. The equation of a circle (including a line) for example is given by the equation κ ( s ) = 1 r {\displaystyle \kappa (s)={\tfrac {1}{r}}} where s {\displaystyle s} is the arc length, κ {\displaystyle \kappa } the curvature and r {\displaystyle r} the radius of ...
If k = −1, then (loosely speaking) one can say that i · a is the radius of curvature of the universe. a is the scale factor which is taken to be 1 at the present time. k is the current spatial curvature (when a = 1). If the shape of the universe is hyperspherical and R t is the radius of curvature (R 0 at the present), then a = R t / R 0
The radius of curvature usually is taken as positive (that is, as an absolute value), while the curvature κ is a signed quantity. A geometric approach to finding the center of curvature and the radius of curvature uses a limiting process leading to the osculating circle. [30] [31] See image above.