The force of friction which is introduced when there is no relative motion between the surfaces in contact is called _____?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Static Friction
Static friction acts between two surfaces in contact when neither slides over the other. It grows with the applied force and holds the body at rest until the force reaches a limiting value; beyond that the body starts to slide.
Why the other options are incorrect
Option (2) Kinetic Friction — Incorrect. Kinetic (sliding) friction acts while one surface is sliding over the other, that is, when there is relative motion.
Option (3) Centripetal Force — Incorrect. It is the force towards the centre that keeps a body moving in a circle, not a kind of friction.
Option (4) Centrifugal Force — Incorrect. It is the outward pseudo force felt by a body in a rotating frame, not a kind of friction.