A 0.50 kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the mass is at the highest point of the circle the speed of the mass is 8.0 m/s. What is the magnitude of the force of the string on the mass at this position?
◦ 21 N
◦ 11 N
◦ 16 N
◦ 26 N
◦ 36 N