A collar B of mass 2 kg is constrained to move along a  horizontal smooth and fixed circular track of radius 5 m. The spring lying in the plane of the circular track and having soring constant 200 N/m is un-deformed when the collar is at A. If the collar starts from rest at B, the normal reaction exerted by the track on the collar when it passes through A is :

1440 N

Initial extension = 6 m

Initial energy = \(\frac{1}{2}*200*6^2 = 3600 \text{ J}\)

Reaching A, we get : \(\frac{1}{2}mv^2 = 3600 \text{ J}\)

\(mv^2 = 7200 \text{ J}\)

\(N = \frac{mv^2}{R} = \frac{7200}{5}\)

  = 1440 N