Module 3

Question 1

centre of gravity

Answer 1

the point of conc of the entire weight of the body

Question 2

centroid of an area

Answer 2

geometric center of an area where the entire area is assumed to be concentrated

Question 3

theorems of pappus-guldinus

Answer 3

theorem 1:
the area of surface generated by revolving a plane curve about a non intersecting axis in the plane of the curve is equal to the product of length of curve and the distance travelled by the centroid of the curve while the surface is being generated

theorem 2:
the volume of the body generated by revolving a plane of area about a non intersecting axis in the plane of area is equal to the product of area and the distance travelled by the centroid of the plane area while the body is generated

Question 4

moment of inertia

Answer 4

the relative distribution of area with respect to some reference axis

Question 5

radius of gyration

Answer 5

k= sqrt(I/A) with respect to given axis

Question 6

Perpendicular axis theorem

Answer 6

if Ixx and Iyy are the moment of inertia of an area about mutually perpendicular axis XX and YY in the plane of area, then the moment of inertia of the area about the ZZ axis which is perpendicular to XX and YY axis and passing through the point of intersection of XX and YY is given by Izz=Ixx+Iyy

Question 7

polar moment of inertia

Answer 7

moment of inertia about ZZ axis which is perpendicular to XX and YY axis and passing through the point of intersection of XX and YY

Question 8

parallel axis theorem

Answer 8

if Ig is the moment of inertia of a plane lamina of area A about its centroidal axis in the plane of lamina then the moment of inertia about any axis AB which is parallel to centroidal axis and at a distance h from centroidal axis is given by: Iab=Ig+Ah^2

Question 9

inertia

Answer 9

property by virtue of which it resists any change in state of rest or of uniform motion