Sir, my name is Cyril Johnson and I am from Jabalpur.I am greatly thankful to elessar_iitkgp  and biki(303) for helping me in the previous kinematics problem.Sir, I am new to this site and I dont know how to rate the Genius like you all.So, kindly excuse me.I will learn it soon.

Sir,now i have a different question for you.

a 2Kg block is fixed at one end of a 3 mt long string(radius of the exibited motion) and released from horizontal position.find the minimum velocity required to keep the circular motion going.

Sir, is this practically proven?Please kindly explain me the physics behind it.