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Delaware and Hudson Canal

(Encyclopedia)Delaware and Hudson Canal dĕlˈəwâr, –wər [key], former waterway, 108 mi (174 km) long, between Honesdale, Pa., and Eddyville, N.Y. (now in Kingston), linking the Delaware and Hudson rivers; bui...

pitchblende

(Encyclopedia)pitchblende pĭchˈblĕndˌ [key], dark, lustrous, heavy mineral, a source of radium and uranium. Largely natural uranium oxides, triuranium octaoxide (U3O8) and uranium dioxide (UO2), it usually cont...

pendulum

(Encyclopedia)pendulum, a mass, called a bob, suspended from a fixed point so that it can swing in an arc determined by its momentum and the force of gravity. The length of a pendulum is the distance from the point...

‘Oumuamua

(Encyclopedia)‘Oumuamua ōmo͞oˈəmo͞oˈə [key], officially 1I/2017 U1 (‘Oumuamua), interstellar object, the first to be discovered in the solar system. Highly variable in brightness, it also is highly and u...

separator, cream

(Encyclopedia)separator, cream, dairy machine used to separate fresh whole milk into cream and skim milk. Formerly the separation was made by the gravity method, allowing the cream to rise to the top of a pan and t...

fifth force

(Encyclopedia)fifth force, postulated fifth basic force of nature (the four known forces of nature are gravity, electromagnetism, and the strong and weak interactions). Proposed in 1986 to account for gravitational...

Penrose, Sir Roger

(Encyclopedia)Penrose, Sir Roger, 1931–, British mathematical physicist, Ph.D. Cambridge, 1958. He taught and conducted research at a number of British and American colleges and universities before becoming a pro...

taxis

(Encyclopedia)taxis tăkˈsĭs [key], movement of animals either toward or away from a stimulus, such as light (phototaxis), heat (thermotaxis), chemicals (chemotaxis), gravity (geotaxis), and touch (thigmotaxis). ...

center of mass

(Encyclopedia)center of mass, the point at which all the mass of a body may be considered to be concentrated in analyzing its motion. The center of mass of a sphere of uniform density coincides with the center of t...

tropism

(Encyclopedia)tropism trōpˈĭzəm [key], involuntary response of an organism, or part of an organism, involving orientation toward (positive tropism) or away from (negative tropism) one or more external stimuli. ...