Question

One end of a string of length l is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v the net force on the particle (directed towards the centre) is: 

(i) T

(ii) T - mv²/l

(iii) T + mv²/l

(iv) 0

T is the tension in the string. [Choose the correct alternative].

Answer 1

(i) T 

When a particle connected to a string revolves in a circular path around a centre, the centripetal force is provided by the tension produced in the string. Hence, in the given case, the net force on the particle is the tension T, i.e.,

F = T = mv²/l

Where F is the net force acting on the particle.