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) $T-\frac{m{v}^2}{l}$
(iii) $T+\frac{m{v}^2}{l}$
(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.,
$F=T=\frac{m{v}^2}{l}$
Where F is the net force acting on the particle.