Question

One end of 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

• A. zero
• B. $T-\frac{m{v}^2}{I}$
• C. $T$
• D. $T+\frac{m{v}^2}{I}$

Answer 1

Answer: (D)

When particle moves in a circle, then the resultant force must act towards the centre and its magnitude F must satisfy
$F=\frac{m{v}^2}{I}$
This resultant force is directed towards the centre it is called centripetal force.This force originates from the tension T
Hence, $F=\frac{m{v}^2}{I}=T$