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 center) is:
1. \(T\)
2. \(T-\frac{m v^2}{l}\)
3. \(T+\frac{m v^2}{l}\)
4. \(0\)

A stone of mass \(0.25\) kg tied to the end of a string is whirled around in a circle of radius \(1.5\) m with a speed of \(40\) rev/min in a horizontal plane. The tension in the string is:
1. \(5.6\) N
2. \(6.6\) N
3. \(3.4\) N
4. \(4.2\) N