A particle of mass m is tied to a light string and rotated with a speed v along a circular path of radius r. If T is tension in the string and mg is gravitational force on the particle then, the actual forces acting on the particle are

When the observer is on the ground (inertial frame) , real forces mg and T , only act on the particle.When the observer is on the particle itself (non-inertial frame) pseudo force (mv2/l) appears to be acting on the particle , also real forces mg and T act on the particle.