2. (37pt) A mass on is placed on a table with higher a, and is tie with a string with a length a to a mass with a mass mg. The string passes through a hall in the table such that \"32 suspending in the air1 and can move like a pendulum. Gravity points down. See illustration in Figure 2. Figure 2: Two friasses connected by a string with iength a, one is set on a table. (a) (5pt) How many degrees of freedom the system has? 1 (b) (6pt) Write the zero surface, constraint equation(s)