A 980 gr rock is whirled in a horizontal circle at the end of a 1.8 m long string. If the breaking strength of the string is 150 N, and at the minimum angle the string can make with the horizontal, what is the speed of rock? (g=9.8 m/s2) 

Group of answer choices

 12.39 m/s

 16.57 m/s 

0 m/s 

15.36 m/s 

19.85 m/s