(a) A block of mass m, initially at angular position 0 = 0, is sliding up a frictionless circular arc of radius R with initial speed given by v = , as shown below. Gravity acts downwards. Show that, in order for the bilock to reach the top of the arc (8 = 180) while remaining in contact with the arc, the initial velocity must be greater than tg = (5gR)/2 (8 marks). (b) Now, in addition to the conditions in part (a), a constant tension 0