One end of string of length L is connected to a particle of mass ‘m’ and the other end is connected to a small peg on a smooth horizontal table. If the particle moves in circle with speed ‘v’, the net force on the particle (directed towards center) will be : (T represents the tension in the string)

T 

Centripetal force \(\frac{m v^2}{L}\) is provided by tension so the net force will be equal to tension i.e. T.