ABSTRACT
A rigid body is one that does not deform under the action of forces. Thus, the distance between any two points in a rigid body is constant, and this imposes constraints on their relative motions. This chapter considers the motion of any point in a rigid body. The motion of a rigid body is said to be planar if all the points in the body undergo motion in planes that are parallel to one another. If one of these planes is the xy plane, then we may confine our attention to the cross section of the body that lies in the xy plane. All other cross sections that lie in planes parallel to the xy plane will then have identical motions relative to the x, y, z axis system. Velocity and acceleration are vector quantities, and, as with the analysis of force systems, it is often useful in the solution of problems in kinematics to draw the appropriate vector diagram.
