Suppose that 6 J of work is needed to stretch a spring from its natural length of 34 cm to a length of 49 cm. How do you answer (a) and (b)?

Suppose that 6 J of work is needed to stretch a spring from its natural length of 34 cm to a length of 49 cm.

(a) How much work is needed to stretch the spring from 42 cm to 47 cm? (Round your answer to two decimal places.)

W = ??? J

(b) How far beyond its natural length will a force of 15 N keep the spring stretched? (Round your answer one decimal place.)

x = ??? cm