A circle of radius rolls without slipping along the –axis

MATHEMATICS · Multi-part · A Level · Mathematics · Integration · Integration

Problem

A circle of radius r>0r>0 rolls without slipping along the xx–axis, generating one arch of a cycloid. The arch is traced by a point on the rim of the circle and is given parametrically for 0≤t≤2π0\le t\le 2\pi by x(t)=r(t−sin⁡t),y(t)=r(1−cos⁡t).x(t)=r\bigl(t-\sin t\bigr), \qquad y(t)=r\bigl(1-\cos t\bigr). Let S be the region bounded above by the cycloid and below by the xx–axis on this interval. (a) Verify that the endpoints of the arch lie on the xx–axis and determine their xx–coordinates in terms of rr. Conclude that S is a finite region. (b) Write a definite integral that gives the exact area of S. Clearly indicate the limits of integration but do not evaluate yet. (c) Evaluate the integral from part (b) and simplify the result completely, showing all steps. (d) Interpret the numerical factor in your final answer in part (c) in the context of the geometry of the cycloid.

Related theory

Browse the problem library