Questions involving a mass on a string or pendulum moving in a vertical circle, requiring analysis of critical speed, tension, or velocity at various angular positions.
164. A pulley whose string length is 2 meters and ball mass is 2kg, starting from a position where the string makes a $53^\circ$ angle with the vertical, is released from rest. The tension in the string at the moment it makes a $37^\circ$ angle with the vertical is how many Newtons? ($\sin 37^\circ = 0.6$, air resistance is negligible, $g = 10\,\frac{m}{s^2}$) (1) $16$ (2) $20$ (3) $24$ (4) $36$