UPSC 2013 CDS 2 GK Paper

Magnetic, electrostatic and gravitational forces come under thecategory of non contact forces. A non-contact force is a force whichacts on an object without coming physically in contact with. The mostfamiliar example of a non-contact force is weight. In contrast, acontact force is a force applied to a body by another body that is incontact with it, for example: muscular force, frictional force.