Suppose that 3 J of work is needed to stretch a spring from its natural length of 26 cm to a length of 39 cm. (a) How much work is needed to stretch the spring from 30 cm to 34 cm? [Round your answer to two decimal places.) x: {b} How far beyond its natUIal length will a force of 30 N keep the spring stretched? [Round your answer one decimal place.) x cm