Strength of Materials
In the equation of virtual work, following force is neglected

reaction of a rough surface of a body which rolls on it without slipping
reaction at a point or an axis, fixed in space, around which a body is con-strained to turn
reaction of any smooth surface with which the body is in contact
All of the listed here

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Strength of Materials
Center of percussion is

the point of metacentre
the point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
point of suspension
the point of C.G.

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