Solve the all parts of following problem:
Problem: A 980-g rock is whirled in a horizontal circle at the end of a 1.4-m-long string.
Part I: If the breaking strength of the string is 160N, what is the minimum angle the string can make with the horizontal?
Part II: At this minimum angle, what's the rock's speed?
I need help to solve the above problem and express your answer to two significant figures and include the appropriate units.