A.2.24—Centripetal force

Centripetal force is a resultant

Centripetal force is the name for the net inward force required for circular motion:

$$F_c=ma_c=\frac{mv^2}{r}$$

Identify its physical source

Centripetal force is not an extra force. It may be supplied by tension, gravity, friction, normal force, electric force or a combination of forces.

Keep the direction clear

The required resultant points toward the centre and is perpendicular to instantaneous velocity in uniform circular motion.

Common trap

Do not add a separate “centripetal force” arrow to a free-body diagram unless the question explicitly uses it as a shorthand for the inward resultant.