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  2. Aristotle's wheel paradox - Wikipedia

    en.wikipedia.org/wiki/Aristotle's_wheel_paradox

    The paradox is that the smaller inner circle moves 2πR, the circumference of the larger outer circle with radius R, rather than its own circumference. If the inner circle were rolled separately, it would move 2πr, its own circumference with radius r. The inner circle is not separate but rigidly connected to the larger.

  3. Area of a circle - Wikipedia

    en.wikipedia.org/wiki/Area_of_a_circle

    Circumscribe a square, so that the midpoint of each edge lies on the circle. If the total area gap between the square and the circle, G 4, is greater than D, slice off the corners with circle tangents to make a circumscribed octagon, and continue slicing until the gap area is less than D. The area of the polygon, P n, must be less than T.

  4. Circular motion - Wikipedia

    en.wikipedia.org/wiki/Circular_motion

    The tangential force is zero at the top (as no work is performed when the motion is perpendicular to the direction of force). Since weight is perpendicular to the direction of motion of the object at the top of the circle and the centripetal force points downwards, the normal force will point down as well.

  5. Work (physics) - Wikipedia

    en.wikipedia.org/wiki/Work_(physics)

    The ancient Greek understanding of physics was limited to the statics of simple machines (the balance of forces), and did not include dynamics or the concept of work. During the Renaissance the dynamics of the Mechanical Powers, as the simple machines were called, began to be studied from the standpoint of how far they could lift a load, in addition to the force they could apply, leading ...

  6. Circle - Wikipedia

    en.wikipedia.org/wiki/Circle

    As proved by Archimedes, in his Measurement of a Circle, the area enclosed by a circle is equal to that of a triangle whose base has the length of the circle's circumference and whose height equals the circle's radius, [11] which comes to π multiplied by the radius squared: =.

  7. Tautochrone curve - Wikipedia

    en.wikipedia.org/wiki/Tautochrone_curve

    The curve is a cycloid, and the time is equal to π times the square root of the radius (of the circle which generates the cycloid) over the acceleration of gravity. The tautochrone curve is related to the brachistochrone curve, which is also a cycloid.

  8. Newton's laws of motion - Wikipedia

    en.wikipedia.org/wiki/Newton's_laws_of_motion

    At any instant of time, the net force on a body is equal to the body's acceleration multiplied by its mass or, equivalently, the rate at which the body's momentum is changing with time. If two bodies exert forces on each other, these forces have the same magnitude but opposite directions. [1] [2]

  9. Liu Hui's π algorithm - Wikipedia

    en.wikipedia.org/wiki/Liu_Hui's_π_algorithm

    Liu Hui's method of calculating the area of a circle. Liu Hui's π algorithm was invented by Liu Hui (fl. 3rd century), a mathematician of the state of Cao Wei.Before his time, the ratio of the circumference of a circle to its diameter was often taken experimentally as three in China, while Zhang Heng (78–139) rendered it as 3.1724 (from the proportion of the celestial circle to the diameter ...