Question

The distance used in the theorem is the distance travelled by ______________

(a) Body

(b) Body’s centroid

(c) Body’s length vector

(d) Body’s radius vector

This question was posed to me during an interview for a job.

This key question is from Theorem of Pappus and Guldinus in portion Centre of Gravity and Centroid of Engineering Mechanics

Answer 1

The correct option is (b) Body’s centroid

Easiest explanation: The theorem is used to find the surface area and the volume of the revolving body. Thus the surface area and the volume of any 2D curve. It is just the product of the area, length of generated curve and the perpendicular distance from axis. The distance being the distance travelled by the centroid.