Cycloid Calculator
Solve cycloid problems step-by-step with our free calculator. See formulas, worked examples, and clear explanations. Enter your values for instant results.
Formula
x = r(t - sin t), y = r(1 - cos t)
The cycloid is defined by parametric equations where r is the radius of the generating circle and t is the rotation angle in radians. One complete arch occurs when t goes from 0 to 2PI. Arc length = 8r, Area = 3PIr^2, and maximum height = 2r.
Worked Examples
Example 1: Standard Cycloid with Radius 5
Problem: Calculate the arc length, area under the curve, and maximum height for a cycloid generated by a circle of radius 5 units for one complete arch.
Solution: Arc length of one arch = 8r = 8 x 5 = 40 units\nArea under one arch = 3 x PI x r^2 = 3 x 3.14159 x 25 = 235.619 sq units\nMaximum height = 2r = 2 x 5 = 10 units\nBase length = 2 x PI x r = 2 x 3.14159 x 5 = 31.416 units\nArea ratio to generating circle: 3:1 (always 3 times the circle area)
Result: Arc Length: 40 | Area: 235.619 | Max Height: 10 | Base: 31.416
Example 2: Point Location at 90 Degrees
Problem: For a cycloid with radius 3, find the x and y coordinates when the generating circle has rotated 90 degrees (PI/2 radians).
Solution: x = r(t - sin t) = 3(PI/2 - sin(PI/2)) = 3(1.5708 - 1) = 3(0.5708) = 1.7124\ny = r(1 - cos t) = 3(1 - cos(PI/2)) = 3(1 - 0) = 3.0000\nAt 90 degrees, the point is at (1.7124, 3.0000)\nThe point has risen to exactly one radius height above the base line.
Result: Position at 90 deg: x = 1.7124, y = 3.0000
Frequently Asked Questions
What is a cycloid and how is it generated?
A cycloid is the curve traced by a point on the circumference of a circle as it rolls along a straight line without slipping. Imagine marking a point on the edge of a coin and then rolling that coin along a flat table while watching the path the marked point traces in the air. That path is a cycloid. The cycloid was first studied by Galileo Galilei in 1599, who named it and tried to determine its area by weighing cut-out shapes. The curve has remarkable mathematical properties and was the subject of intense study by many great mathematicians including Pascal, Huygens, Bernoulli, and Leibniz, earning it the nickname 'the Helen of geometry' because it caused so many intellectual disputes and inspired so much mathematical development.
What is the brachistochrone problem and how does the cycloid solve it?
The brachistochrone problem, posed by Johann Bernoulli in 1696, asks: what is the curve connecting two points at different heights along which a ball rolling under gravity alone will travel in the shortest time? Counterintuitively, the answer is not a straight line but an inverted cycloid. The straight line is the shortest distance, but the cycloid is faster because the ball accelerates more quickly by diving steeply at first, gaining speed that more than compensates for the longer path. This was one of the foundational problems of the calculus of variations. Newton, Leibniz, L'Hopital, and Jakob Bernoulli all independently solved it. The brachistochrone property makes the cycloid important in physics, engineering, and optimal design problems where minimizing transit time is essential.
What is the tautochrone property of a cycloid?
The tautochrone property is one of the most remarkable features of the cycloid. It states that a ball placed anywhere on an inverted cycloid-shaped track and released from rest will reach the bottom in exactly the same time, regardless of where it was placed on the curve. This seems impossible at first glance: a ball placed near the top has farther to travel but starts on a steeper slope, while a ball near the bottom has less distance but a gentler slope. These effects perfectly cancel out for the cycloid. Christiaan Huygens discovered this property in 1659 and used it to design an isochronous pendulum clock with cycloid-shaped cheeks that forced the pendulum bob to follow a cycloidal arc, ensuring the period remained constant regardless of the amplitude of the swing.
What are the parametric equations of a cycloid?
The parametric equations for a standard cycloid generated by a circle of radius r rolling along the x-axis are x equals r times the quantity t minus sine of t, and y equals r times the quantity one minus cosine of t, where t is the parameter representing the angle of rotation of the generating circle in radians. When t equals zero, the point is at the origin, which is a cusp. When t equals pi, the point is at the top of the arch at coordinates r times pi and two r. When t equals two pi, one complete arch is finished and you reach the next cusp. These equations reveal that the base length of one arch equals two pi r, which is exactly the circumference of the generating circle. The parametric form makes it straightforward to calculate derivatives, arc length, area, and other geometric properties.
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