One end of a string of length l is connected to a particle

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].

solution:

Answer: (i)

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.

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